- 1 Xylella fastidiosa
- 2 Khapra beetle
- 3 Fruit flies
- 4 Karnal bunt
- 5 Huanglongbing
- 6 Gypsy moth
- 7 Tramp ants
- 8 Internal and external mites of bees
- 9 Giant African snail
- 10 Brown marmorated stinkbug
- 11 Zebra chip
- 12 Ug99 (Wheat stem rust)
- 13 Russian wheat aphid (holocyclic form)
- 14 Citrus canker
- 15 Guava (Eucaluptus) rust
- 16 Phytophthora blight
- 17 Sudden oak death
- 18 Exotic bees
- 19 Tropical Race 4
- 20 Potato Cyst Nematode
- 21 Leaf miner
- 22 Fire blight
- 23 Hessian fly/Barley stem gall midge
- 24 Texas root rot
- 25 Wheat stem sawfly
- 26 Golden apple snail
- 27 Barley stripe rust
- 28 Cereal cyst nematode
- 29 Sharka
- 30 Drywood termite
- 31 Subterranean termite
- 32 Citrus longhorn beetle
- 33 Red ring disease/Pine wood nematode
- 34 Fusarium Wilt
- 35 Sugarcane stalk borer
- 36 Black Sigatoka
- 37 Potato late blight
- 38 Sunn Pest
- 39 Western/Tarnished plant bug
- 40 Exotic sawyer beetles
- 41 European canker
- 42 Dutch elm disease
Xylella fastidiosa is a Gram-negative bacteria derived from the monophyletic genus Xylella. As an aerobic bacteria, this plant pathogen is transmitted to other plants by sap-feeding insects. The xylem fluid it possesses is contagious and a lot of plant diseases are caused by the symptomatic infections derived from Xylella fastidiosa. With this being said, oleander leaf scorch, Pierce’s disease of grapes, citrus variegated chlorosis, coffee leaf scorch, alfalfa dwarf, phony peach disease, and bacterial leaf scorch are all diseases that result from these symptomatic infections. Olive trees in Europe have even felt the wrath of this disease as it ran rampant throughout the Salento area of Southern Italy. The result was the olive quick decline syndrome. This disease is somewhat rare in North and South America, but there have been issues revolving around its appearance throughout Slovakia, Taiwan, and other countries across the globe.
The big issue with xylella fastidiosa is that with so many plants being asymptomatic carriers of it, the spread is difficult to stop. These bacterium are only pathogenic when there are many infected plants around one another, causing them to colonize. Most of the time, the colonies of bacteria are not adequately sized to the point that they can total block the vessels and the fact of the matter is that the instrument pathogenesis works through is not fully understood.
This bacteria is shaped like a rod and there is at least a single subspecies that possesses two types of pili on a single pole. The longer type of IV pili are utilized for movement as the shorter type I pili help with biofilm formation whilst inhabiting a host. This bacteria uses a twitching motion to allow it to travel against the heavy flow that is found within xylem vessels. The infections usually happen over the course of warmer seasons because the insect vector populations are at a high at this point in the year.
Khapra beetles, or cabinet beetles, are originally from South Asia. The beetles can grow to a size of 1.6 to 3mm in length. Their immature larvae are as large as 5mm in length and coated with thick, red/brown hair. They remain larvae for between four and six weeks but this stage of the Khapra beetle life cycle can extend for as long as seven years. Male Khapra beetles are black or dark brown in color while the females tend to be a little bigger, displaying lighter colors. Once the beetle reaches adulthood, their lifespan is typically from five to ten days. They’re known for thriving in hot, dry conditions and enjoy living where you’ll find grain and other food sources are being stored. The most common places the Khapra beetles call home include gain and fodder processing plants, stores of used grain sacks or crates, malt houses, and pantries.
These insects are the destroyers of seeds and grain products, causing some serious issues within these industries. These are one of the worst invasive species in existence primarily because the infestations are super hard to control. The Khapra beetle is capable of surviving without any food for long durations, but it’s also a bug that prefers dryer conditions as well as food containing little moisture. Insecticides are no match for these beetles as they’ve proven themselves to be quite resilient as well. With this being said, a federal quarantine has been placed on the importing of any rice to the United States from any country that has a Khapra beetle infestation. These beetles are capable of spoiling valuable trade goods and have threated seriously significant economic losses upon it being displaced into an area it can thrive in. If a person handles or ingests grain or seed products that have been contaminated by the Khapra beetle, health issues including gastrointestinal distress and skin irritation can arise.
Fruit flies, or the Drosophila melanogaster species, are commonly found throughout the world. They have a lifespan of approximately 30 days when living in 84 degree Fahrenheit weather and the periods at which the flies develop range with the temperature. These flies take the least time to develop at 82 degrees, going from egg to adult in as few as a week. At higher temperatures, the development times tend to see an increase as a result of heat stress. The conditions at which these flies can develop ranges from 7 days to 50 days, resulting in more time developing the lower the temperature gets. Crowded conditions can have an impact on the development time as well. This also impacts the size of the emerging flies. The more crowded the conditions are, the smaller the emerging flies are. Female fruit flies lay as many as 400 embryos into rotting matter that can include rotting plant matter as well as decaying mushrooms. The embryos are laid around five per period and they’re around 0.5mm long, hatching just 12 to 15 hours upon being laid. Fruit fly eggs are coated with the mother’s fecal matter, allowing her to provide the microbial composition that has allowed her to thrive. This goes into the larvae’s guts and they are then capable of feeding on the microorganisms that are decomposing the matter they’re inside. There is four days of metamorphosis prior to the adult fruit flies emerging from the rotting matter.
If the fruit fly is a female, it will become ready to mate between 8 to 12 hours following it emerging. The male fruit flies are known to have a strong reproductive learning curve. By this, it is meant that they will change their mating behavior in the future, such as their courting dance ceasing or them trying to mate with females that are sexually mature as opposed to sexually immature.
The Karnal bunt is a fungus that originates from India. This pest is found distributed throughout Inida, as well as South Africa, the Middle East, Mexico, and Brazil. Visually speaking, the fungus is characterized by broken hollow grains as well as a strong fishy odor. You’ll also notice that the grain has powdery masses of dark spores that looks a lot like common bunt, loose smut, black point. This pest spreads throughout soil, agricultural products, contaminated machinery, and wheat seeds, showcasing a high risk to grains including durum wheat, triticale, and wheat. Karnal bunt is a super invasive exotic pest of grain that threatens the wheat industry indefinitely. The threat it poses has the potential to devastate not only the quality but the salability of crops that it reaches. Tilletia indica is the culprit of Karnal bunt. It infects the grains while they are flowering and favors the cooler more humid conditions over the dryer hotter climates. When this pest infects grains, it is nearly impossible to get rid of for years. The spores inhabit in soil for as long as four years, making it rather difficult to eradicate.
Karnal bunt can spread rapidly very easily. Naturally spreading, the spores are capable of being carried far and wide by being taken away with the wind. These spores can also pass throughout the digestive tracts of the animals that ingest it, giving it even further ability to migrate throughout an area. Animal manure can bring the fungus spores to areas that it otherwise would be unable to reach. For example, a rat can eat some infected wheat and bring the spores with it into a storage tower rather easily. Internationally speaking, infected wheat seeds are capable of bringing the spores to other countries as well, making it so Karnal bunt is something that major exporters of wheat must be on the search for as they conduct business.
Huanglongbing, or citrus greening disease, is detrimental to citruses across the globe. This disease is incredible destructive and while in the past it was believed that there was a virus as the culprit, the truth of the matter is that it is derived from unculturable phloem-limited bacteria. With this being said, there are a total of three types of greening that we’ve witnessed. Cool conditions can result in the African form of Huanglongbing producing its symptoms. Transmittal of the African form occurs in the African citrus psyllid Trioza erytreae. There is also an Asian form that tends to thrive in warmer conditions. This form is transmitted through the Asian citrus psyllid Diaphorina citri. Presently, there has been a third American form that is being transmitted as well. This is occurring through the Asian citrus psyllid that was found in Brazil. The origin of this form of Huanglongbing is originally from China and migrated to America. North American Huanglongbing is thriving in Hawaii, South Carolina, Georgia, Louisiana, and Florida as the psyllid vector, Diaphorina citri. More recently, there have been cases of this disease being found throughout Mexico and Southern California as well. Huanglongbing has been happening throughout South Carolina, Georgia, Belize, Eastern Yucatan of Mexico, Cuba, Florida, and Louisiana for years now.
With these problems persisting, the federal government has issued quarantine restrictions that will restrict any movement of citrus, as well as various other plants found in the family Rutaceae from Asian Citrus Psyllid or areas that are contaminated with Huanglongbing, into California in an effort to prevent the disease from being introduced to the area. Economically speaking, Huanglongbing has the potential to devastate areas. It was first found in Florida during 2005 and since then, the citrus acreage has seen a serious decline. Allowing the disease to spread to California has the potential to damage the nursery industry indefinitely, forcing it to migrate production under screen houses, increase pesticide costs, and add costs as a result of pesticide necessity causing disruption in the work.
In 1989, the gypsy moth was brought to Massachusetts by accident and by 1902, it was found throughout the New England states as well as regions throughout New Jersey and eastern New York. In northern Pennsylvania, it wasn’t until 1932 that the gypsy moth was found living in Lackawanna and Luzerne Counties. The infestation grew to the point at which this pest is being found throughout southern and western areas around the mountain ridges. By the late 1970s and early 1980s, this infestation was found throughout Huntington, Clearfield, Blair, and Centre Counties. The result was a lot of defoliation as well as subsequent tree mortality throughout the areas found around the mountain ridges. These pests have decimated the oak forests, showcasing how they can be a serious threat to the wilderness in areas that they’re not native to.
The reason why the gypsy moths spread so fast is because of the number of eggs they have per bunch. These are light tan masses of black small balled eggs that range from 400 to 600 eggs per cluster. Upon hatching, the larvae are small caterpillars. These hairy wormlike creatures mature into a larva that ranges from 50 to 65 mm in length, sporting a yellow and black head that is easily recognizable. Upon closer inspection, there is a total of six pairs of brick red spots that follow five pairs of blue spots called tubercles. These are found behind the head along the thorax and abdomen. You’ll see that these pests are dark reddish-brown during their pupa stage and typically sticking to an object using some small silk strands. The males fly throughout the day without hesitation and are rather dark in color while the females are black and white, sporting some wavy markings. Females possess larger abdomens and even with a wingspan of 5 cm, do not fly.
These are one of the most diverse groups of invasive species of ants and as a result, they are now found throughout the world. They’re capable of arriving in areas across the globe as a result of transport pathways. Once they arrive, they can have a seriously negative impact on social and culture values, human health, and ecosystems. There is a minimum of six tramp ant species that are a national priority to control due to the fact that they are capable of having such a profound impact on biodiversity throughout regions. These activities to prevent the spread of them includes monitoring the high-risk areas, dealing with the existing tramp ants, removing the new tramp ants that come into an area, and preventing entry of more tramp ants.
Tramp ants are also some of the most aggressive invasive ants in the world, capable of establishing and spreading throughout areas. Their origin depends on the species but with them being able to spread throughout the world the way that they have, they now currently reside throughout Asia, North America, Africa, Central America, Oceania, South America, and the Caribbean. The shape of these ants is the classic ant body shape and they’re under 5mm in length. Typically, they’re imported into countries by way of imported goods or travelers.
Internal and external mites of bees
These mites originate in Asia and the distribution of them varies from species to species. Looking at them, you’ll notice they possess four pairs of legs as well as a 0.5 mm by 1 mm tropilaelaps and 1.5 mm by 1.1 mm varroa. Traccheal mites are actually invisible to the human eye because they are that small. They tend to find their way into feral bee swarms that are transported across the globe on cargo ships or in containers. With this being said, these mites have a major impact on honey, pollination-reliant food crops, and honey products.
Currently, Australia is just one out of a few countries on this planet that does not have any of these mites or other exotic internal mites of bees. The varroa mite could eventually establish itself in Australia and the result would be catastrophic. They currently have a healthy population of European honey bees and with the introduction of these mites, the pollination services that they grant to this country has the potential to reduce by between 90 and 100 percent. This is a $4-6 billion per year industry that these mites have the potential to devastate. There is a variety of internal and external mites of bees and they are all devious. These include the following:
- tracheal mite – Acarapis woodi (internal)
- The tracheal mite, or Acarapis woodi, is not found in either New Zealand or Australia. Instead, it is found throughout the majority of other areas that produce honey throughout the world. This includes areas like North America, parts of Asia, and Europe.
- varroa mite – Varroa jacobasoni (external)
- These are now found all throughout the world except for in Australia, New Zealand, and a couple other countries in Central Africa.
- tropilaelaps mite – Tropilaelaps mercedesae (external)
- tropilaelaps mite – Tropilaelaps clareae (external)
- These are found in areas such as Asia and Tropilaelaps mercedesae is found all over the areas of mainland Asia and Indonesia. The two species are both actually found in Papua New Guinea as well.
Giant African snail
These snails are some of the biggest terrestrial gastropods known to man. They are characterized by their light to dark brown shell that has vertical stripes that are a darker shade of brown. These snails live for between 5 and 7 years. If they are able to find enough food and there is weather that is conducive to them thriving, they can live as long as 10 years. With this being said, these are one of the most invasive species of snail found on this planet.
Also known as the “Achatina fulica,” these snails are seen as one of the species that damage the agricultural industry the most. The United States Department of Agriculture has found this snail to devour a minimum of 500 different species of plants, making it a versatile invasive species that will eat nearly anything it can get its mouth on. They are found on the list of 100 most harmful invasive alien species in the world. This being said, these snails are versatile in relation to where they can live as well. They do not have to depend on their natural habit but instead, can inhabit areas that differ from it. Their small teeth give them the ability to scrape food prior to eating it as well. These snails are so invasive that it is against the law for a person to have them as a pet in the United States!
Brown marmorated stinkbug
These insects belong to the family Pentatomidae and are native to Taiwan, China, the Koreas, and Japan. They were first introduced by accident in the United States with the first one being found in September of 1998. These are seen as an agricultural pest and within a couple of years, the United States orchards were experiencing them as a season-long pest. They have also recently become established in South America as well as Europe. The problem with these bugs is that they are capable of causing some serious damage to agricultural crops including fruits and vegetables. The soybean and fruit crops are severely impacted by these pests in Japan and the United States experiences them throughout late May or early June as they eat a multitude of fruits and vegetables including apples, green beans, cherries, soybeans, pears, and raspberries. To eat, the bugs pierce the host plant and this results in dimpled and necrotic areas being found on the outside surface of fruits, seed loss, transmissions of plant pathogens, and leaf stippling.
The adult brown marmorated stinkbug measures around 0.67 inches in length and approximately just as wide. Their shape is that of a shield that is similar to other stink bugs one might find. The coloring of these bugs includes brown on the top as well as undersides along with gray, black, off-white, bluish, and copper markings. These markings are special and this species also has some changing light bands that are found on their antennae as well as some alternating dark bands that are found on their abdomen on the thin outer edge of it. They also have brown legs that possess a light bit of faint white. These stink bugs possess stink glands too. They’re found on their thorax’s underside right between their first and second pair of legs. Also, the dorsal surface of their abdomen has a stink gland.
The zebra chip is also called papa machada as well as papa rayada. This is a disease that is found in potatoes. Caused by alphaproteobacteria called Candidatus Liberibacter solanacearum, this disease makes it so that when the infected potatoes are fried, the chips will have some black lines that are comparable to those found on zebras. This makes it so the chips are not able to be sold. The striped portions of the potato chips are usually burned or caramelize, making it so the chips are bitter in flavor. There aren’t any health risks associated with eating these infected chips, but the taste is not appealing to most.
Zebra chip was first found in Saltillo, Mexico in 1994. The original name of the disease was papa manchada, or stained potato. During the early 1990s, there were cases of the disease being found throughout potato farms in Texas. It was not known what the disease for nearly a decade. Ever since this disease came about, it has been found throughout various regions in the United States including California, Arizona, New Mexico, Oregon, Kansas, Nebraska, and Colorado. Guatemala has also made reports showing that the disease has been occurring in the country since May of 2008. This was when a greenhouse in Auckland made a report of finding potatoes exhibiting the same symptoms.
It is believed that the namesake sign of zebra chip is the result of potato starch being transformed into a water-soluble sugar. This makes the stripes occur when they are cooked. There is another study showing that this discoloration might be the result of enzymatic browning that involves a polyphenol oxidase. This disease’s symptoms are sometimes even seen prior to the potato being harvested. These signs can include leaf scorching, swollen nodes, vascular tissue browning, chlorosis, and curled leaves.
Ug99 (Wheat stem rust)
This disease is the result of a fungus that is called Puccinia graminis. Wheat stem rust affects cereal crops immensely and the crop species that feel the most impact from it include durum wheat, triticale, barley, and bread wheat. Over the course of history, cereal farming has felt the impact of these diseases. Beginning in the 1950s we’ve seen that wheat strains had to be bred with resistance to stem rust. Farmers have also been observed utilizing fungicides as well as they are good ways to prevent wheat stem rust.
There is a new virulent species of wheat stem rust that came about in 1999. This species was able to get past any resistance that the current wheat strains had to other species, making it very bad. TTKSK is the name of the disease, also known as Ug99. It was first identified in Uganda, providing a reason for the “Ug” in Ug99. This is one of the most virulent diseases known to man and it spreads like an epidemic. It has been found spreading throughout the Middle East, Asia, and Africa, giving a reason for the numerous people who depend on wheat to provide them with their nutrition. With this being known, breeding the wheat to be resistant to this disease is necessary.
This fungus attacks the components of plants that are found above the ground. with this being known, there are spores that will land on the green wheat plants and when they do, they form a pustule that infects the outside layers of the plant’s stalk. Fewer tillers are produced and fewer seeds are set by plants that are infected with Ug99, resulting in a serious reduction in relation to the amount of healthy crop that is being produced. In essence, the fungus infection results in immense yield losses.
Russian wheat aphid (holocyclic form)
Russian wheat aphids are some serious pests that affect cereal crops like no other. these first arrived in the United States in 1986 and over the course of its presence, it has been a significant invasive species. These bugs are pale green in color and only grow up to around 2 mm in length. The cornicles are not very long, but they’re rounded and seemingly lacking. They have an appendage that is located just above the cauda that make it seem as though the aphid has two tails. These bugs have toxic saliva as well, resulting in plants having a whitish striping on their leaves. When this aphid feeds, you’ll also notice that the flag leaf will become white and curled. This curling happens around the head and it causes complete head emergence. The host plants include cereal crops such as barley and wheat. Barley is not as often infected as wheat but the aphids will still go after it. Wild grasses including brome-grasses, ryegrasses, wheatgrasses, and really any plant in the grass family can be eaten by the aphids as well.
These aphids are native to southwestern parts of Asia but they have been introduced to many other countries found throughout Africa and Europe. It wasn’t until 1986 that these aphids were found in the United States in Texas. The idea behind how they got there is that they likely came through in some wheat imports. With this in mind, wheat and barley in the United States are now feeling the effects of the Russian wheat aphid, resulting in damages through nutrient drainage of the crops. Feeding on the host plant using the phloem, the aphids damage the plants immensely and the result is wilting, stunting, necrosis, chlorosis, and a variety of other growth impairments that affect the crops throughout the world.
Citrus canker is a bad disease that really impacts periods of shoot emergence as well as early fruit development. It typically happens in areas that have a lot of rainfall and warm temperatures as well. With this said, areas that have a lot of tropical storms will see this disease running rampant. This disease is primarily leaf-spotting and fruit rind-blemishing, but if the conditions are just right for the infection, the infections will result in shoot dieback, fruit drop, and defoliation.
The first impact that citrus canker will have on a plant is leaf lesions. These lesions begin as pinpoint spots and grow as big as 2 to 10 mm in diameter! The size of these lesions will depend primarily on how old the host tissue is when it is infected and on the citrus cultivar. Following around 7 to 10 days of being infected, the lesions will become visible and you’ll see the infections along the underside of the plant’s leaves. Not long after, you’ll notice the upper surface of the leaves will have lesions as well. Both of the surfaces of the leaves will have raised areas but you’ll notice this even more along the underside of the leaf. Eventually, these lesions get a corky look about them, characterized by a sunken center with a raised margin. One of the qualities these lesions also possess includes a yellow halo surrounding the lesions.
With citrus canker comes lesions on fruits and stems as well. These get around 1mm in depth and are comparable to what you’ll find on the leaves. The lesions on these components of the plants range in size due to the fact that the rind is vulnerable over the course of a longer period of time than the leaves and the capability of having more than a single infection cycle is a possibility. the stem lesions are also capable of supporting long-term bacterial infections.
Guava (Eucaluptus) rust
Guava rust, or Psidium guajava – Myrtaceae, is a disease that is typically found in the guava trees throughout Brazil. The infections from guava rust impact the young leaves, flowering buds, young fruit, green shoots, and flowers. This is an autoecious rust pathogen that attacks and results in symptoms found throughout the jamb (Eugenia jambos), guava, Eucalyptus spp, and jaboticaba (Myrciaria). Controlling guava rust is rather difficult but it’s possible through the utilization of cultural methods as well as fungicides. It’s a rust disease that seriously negatively impacts the natural forests and plantations of Eucalyptus spp throughout the regions of Australia and Southern Africa as well.
This fungus originates in Brazil and is found distributed throughout Central America, the Caribbean, South America, the United States (primarily Florida and Hawaii), South Africa, Oceania (New Caledonia, and Asia. The disease is commonly characterized by the yellow tinting in the form of pustules found on the young leaves, fruits, shoots, and stems of the plants. This disease is also spread through a variety of pathways, including plant propagative material, being wind-blown to other plants, human-assisted movement, and contaminants found on clothing as well as machinery.
If you’re a grower or even a home gardener and you see signs of guava rust in your plants, you’ll want to reach out and report the sighting to the Exotic Plant Pest Hotline. Reaching out to them will allow you to speak to the Department of Primary Industries or agriculture that is in your locality. Regardless of your state or territory, you should have no trouble contacting them with your report of this disease and they will surely appreciate the information (as will other growers and home gardeners). This disease results in insane losses (between 80 and 100%) of guava plants, making it one of the more costly pathogen infections to lose a yield to.
The fungus Phytophthora capsici is the cause of Phytophthora blight and this disease has a seriously negative impact on plants. This disease goes by a few different names, including Phytophthora root rot, stem and fruit rot, and crown rot. These names can be applied to this disease because of the fact that they impact all of these components of the plant.
Over the last 40 years, we’ve been watching this disease happen throughout New York randomly. Furthermore, it has had serious negative impacts on crops found throughout New Mexico, Florida, California, and New Jersey. With a variety of crops being impacted throughout New York, this disease takes its toll on tomato, winter squash, pumpkin, summer, and eggplant. There have been other hosts that are being reported as well. These include watermelon, honeydew melon, and cucumber. It’s a pathogen that is the culprit behind the problems found in the latter crops and it’s either Phytophthora parasitica or P. capsici.
This disease attacks the stems, leaves, fruit, and roots of plants and it all depends on the stage that the plants are being affected during. Growers that are unfamiliar with this disease have the potential to confront it during mid-season when they notice sporadic wilting and death happening throughout their plants as they reach their fruiting stage. Plants that are infected and noticed early on are killed immediately but the ones that are later-infected showcase irreversible wilt. A lot of the time, you’ll see a lot of plants that are lined up or in a circular pattern will have the same symptoms simultaneously.
The seedlings of plants will get infected by the fungus as well but it is more common for the disease to attack older plants, showing early wilting. You’ll also notice stem lesions happening at the soil line. Leaves will have small dark green spots that get bigger and bleach as though they’ve been burned. Irreversible wilting of the foliage will happen if the plant’s stems get infected. If a fruit is infected, you’ll see dark, water-soaked patches that get white mold and fungus spores. The fruits will wither and the seeds become shriveled as the fungus infests everything.
Sudden oak death
The plant pathogen Phytophthora ramorum caused sudden oak death, a forest disease. As the susceptible trees get infected by this pathogen, it’s easy to see why the name makes sense. The trees impacted by this disease include tanoak, Shreve’s oak, California black oak, canyon live oak, and coast live oak. Once a tree is infected, the infection occurs in the tree’s trunk (besides the tanoak as it is capable of being infected through its leaves as well as its trunk). These are all bole hosts and there are other kinds of hosts this disease can impact. The other plants found in the forest that are impacted by this disease include the coast redwood, madrone, Douglas-fir, and a variety of other plants. The infections will typically happen mainly on twigs and leaves and they’re considered Ramorum blight (this is a typically non-lethal version of the disease).
This disease is found in a multitude of natural areas, including the northern and central coast of California. We’ve also seen this disease in a county found in southwest Oregon. Currently, all of the natural areas that this disease occurs in are characterized by moisture, coolness, and frequent fog. The forests that have this disease are composed of a combination of host and associated host plants and will usually either have California bay laurel trees or tanoak within the proximity. The nursery system of the host and associated plants will also showcase this disease, causing reason for extensive surveying of the high-risk areas. There are actually compliance agreements that have to be in place prior to nurseries found in areas that are naturally infested with the disease shipping out host and related plant material. Furthermore, if a California nursery containing host and related plants wants to ship throughout the states, they are put on hold and must have an inspection prior to allowing them to continue shipping.
Exotic bees are insects that are found throughout the world. Their origin really depends on what species they are, but they’re distributed throughout the regions of Africa, the Middle East, North America, South America, and Asia. These insects feature a variety of sizes and they grow as large as 2 centimeters in length. Their striped abdomens characterize them, as does their ability to gather in swarms as opposed to flying solo. They’re spread across the globe through the utilization of imported vehicles, machinery, conveyances, and good. With this bees come a variety of risks as well, including risks to honey products, honey itself, and food crops that require pollination.
These bees are some of the biggest threats to healthy populations of European honey bees in Australia. With this being said, it is possible for some species of exotic bees or even bees containing diseases to get established in areas that the European honey bees reside, resulting in catastrophic impacts that could disrupt a lot of honey and food crop production. The bees impacted do not solely create the honey found in Australia, but pollinate various crops throughout the world. The primary exotic bee species that produce these threats include the dwarf, Cap, African, Africanized, and Asian honey bees. With honey bees being such a majorly important component of the horticulture and agricultural industries found all over the world, it’s not hard to see that with exotic bees threatening the bees that people rely on for pollination and honey production have the potential to disrupt multiple industries by becoming established throughout the world.
Exotic bees are a growing global problem so if you see any bees that don’t look like European honey bees, make sure to report them. An infestation is capable of having a serious negative impact on several industries, making it imperative that exotic bees be taken care of immediately.
Tropical Race 4
Banana plant roots are suffering from Tropical Race 4. This disease is a kind of Fusarium wilt that results from the infectious fungal pathogen Fusarium oxysporum f. sp. cubense. It’s not impacted by fungicide and is impossible to control chemically, making it a threat to be reckoned with. Throughout the 1950s, this disease was observed wiping out the majority of commercial Gros Michel banana production. At this point in time, the Gros Michel banana was one of the bananas being cultivated the most and with this infectious fungus, the producers were forced to find other disease-resistant crops. Currently, there are new strains of Tropical Race 4 that are threatening the product of one of the most popular cultivars on the planet, Cavendish.
So when Tropical Race 4 infects a plant, you’ll notice a variety of symptoms. You’ll see yellow leaf syndrome occur on the plant, characterized by the yellowing of the outline of the leaves and over time, the petiole will begin to bend. Green leaf syndrome is another symptom, resulting only in some types of cultivars. This is when the leaves remain green by the petiole of the leaves still bends. Internally speaking, this disease results in vascular discoloration as well. The yellowing starts at the roots and rhizomes and eventually evolves into a reddish brown color found in the pseudostem.
This is different than the bacterial wilt of a banana and there are a couple of easy ways to spot the differences. With Fusarium wilt, you’ll notice it happens from the older to the younger leaves. In the bacterial wilt, you’ll see that this occurs from the younger leaves to the older ones. Also, Fusarium wilt does not have any symptoms occurring with its growing buds and suckers, the fruit will not have symptoms, and there aren’t any exudates found within the plant. With bacterial wilt, you’ll see necrotic or distorted buds, fruit rot and necrosis, and bacterial ooze inside the plant.
Potato Cyst Nematode
With potato cyst nematodes, you’ll notice that they’re roundworms that come from the genus Globodera, a genus with approximately 12 species. These are 1 millimeter in length and live off the roots of plants found in the Solanaceae family. The plants that are in this family include tomatoes and potatoes. The problem with these roundworms is that they result in growth retardation and if they are occurring in super high population densities, they will actually damage the roots as well as the early senescence of the plants. Potato cyst nematodes do not originate in Europe but rather came from the Andes. It is not until the introduction of these roundworms into a field that these patches or hotspots full of potato cyst nematodes occur. Full on infestations will occur if patches of potato cyst nematodes are not dealt with and they can result in an absurd yield reduction of as much as 60 percent if there is a large enough population that is dense enough.
It is possible to reduce how fast the potato cyst nematodes will spread by ensuring that the equipment being used is cleaned every time a location is changed. Infested soil has the potential to allow the spread of these roundworms if one is not careful. You should also ensure you solely use PCN-free seed tubers to slow down the spread. Seed potatoes grown in fields that were gone over with an AMI-intensive soil sampling scheme and found to be clean of the potato cyst nematodes should be requested. Reducing the nematode population densities is also possible by conducting crop rotation with a minimum of 6 years between planting any crop that is susceptible to the potato cyst nematodes. There are a lot of different types of plants that have been developed throughout the last decade that ensure potato cyst nematodes are under control without being forced to utilize pesticides as well.
Leaf miners are typically the larvae of moths, sawflies, and flies, but there are some beetles that exhibit the same kind of behavior. These are the larvae of these insects and they live inside of and devour the tissue of the leaves found on some plants. Similar to the woodboring beetle, leaf miners protect themselves by borrowing inside of the tissue of plant leaves.
While they are inside of these tissues, they consume the layers of the leaves that possess little cellulose. They will attack Quercus robur, or English oak, and eat the tissue that has low levels of tannin. Tannin is a chemical that the tree produces a lot of for the purpose of deterring its consumption.
You’ll notice that these creatures have a feeding pattern in the shape of a tunnel that goes throughout the leaf. This is the impact they have on leaves as they are being mined and the pattern it depends on the insect that is creating the tunnels. Different species will have different patterns. You’ll also see that the mine will often times have larva droppings and looking over the dropping deposition, shape of the mine, and the identity of the host plant are usually enough to give an idea of the type of leaf miner that is found within the plant. Some leaf miner insects will consume other pieces of the plants they inhabit as well, including the surface of fruits.
The suggestion that the patterns of some leaves might even be used as a defensive strategy to deter adult leaf miners into believing that the leaf has been consumed already as well. These pests are also hated by farmers and gardeners alike as they damage garden plants as well as agricultural crops. They’re also rather hard to control because the larva is protected within the leaves of the plants.
This contagious disease is known for impacting pears, apples, and several other members of the Rosaceae family. It is known to pose a serious threat to the producers of pears and apples as well as with the right conditions, it is not difficult for fire blight to render entire orchards of the fruit inedible in a one growing season.
Erwinia amylovora is the pathogen that causes fire blight. This pathogen is derived from the family Enterobacteriaceae. With this being said, the pear is the most susceptible fruit to this disease while apples, crabapples, quinces, pyracantha, raspberry, cotoneaster, loquat, and a variety of other rosaceous plants are susceptible to the disease as well. It is thought that this disease is native to North America but since its existence has become known, it has gone global and spread.
One place that fire blight is not currently found is Australia, though there is some potential for it to exist somewhere there. The reason that Australia has managed to avoid this disease for so long is that is has a long-standing embargo on all New Zealand apple imports coming to the country. It is also thought that Japan does not have this disease occurring as well but over time, it was found that the disease is impacting some pears that are being grown in the northern region of the country. Even with this finding, the Japanese authorities do not admit to it existing in Japan and following his name being leaked to the farmers impacted by the disease, the Japanese scientist who found it is thought to have killed himself. The disease is even found in Europe. Europe has fire blight listed as a quarantine disease but that has not stopped it from making its way throughout Hawthorn (Crataegus) hedges found along the railways, main roads, and motorways.
Hessian fly/Barley stem gall midge
As a species of fly that negatively impacts cereal crops that include barley, rye, and wheat, the Hessian fly or barley midge is one of the worst pests to hit this industry. The Hessian fly is an Asia native but it found its way to Europe and eventually, North America. It is believed that it made it to these other countries concealed in the straw bedding of the Hessian troops that were used throughout the American Revolution over the course of 1775 throughout 1783.
With this in mind, each year has two generations but there is the potential for as many as five. During the spring, you’ll notice the females, darker in color, will lay between 250 and 300 reddish colored eggs on plants. The eggs will usually be laid in areas that the stems are being concealed by leaves. Once the larvae are born, they begin to devour the sap of the plant and as a result, the plants become so weak that they are unable to bear any grain.
Thomas Say gave his depiction of the Hessian fly back in 1817, saying how harmful the insect is and how it primarily will eat the stem. If it has a major appetite, the Hessian fly will eat even more of the plant. There was a really bad Hessian fly infestation that happened back in 1836 and the resulting crop shortage resulted in some serious financial issues. The farmers were severely impacted by this event.
In essence, the Hessian fly is a devastating pest that is capable of making cereal crops so weak that they are unable to produce the life-sustaining grains that farmers need to produce in order to make a living. With this being the case, it’s easy to see that this is a pest you do not want in your fields.
Texas root rot
Texas root rot is known by a variety of terms, including Phymatotrichum, cotton root trot, Ozonium root rot, and Phymatotrichopis root rot. This is a pathogen that is all too commonly found throughout Mexico as well as the southwestern United States. The impact this fungus has on plants can be devastating. It results in the sudden wilting and death of any plants that are affected, usually occurring in the warmer months of the year. This is a fungus that is soil born and comes from the species Phymatotrichopsis omnivore. It is known for attacking susceptible plants at roots, providing a reason for the name of the fungus. Duggar is the man who first gave the fungus its name in 1916 but it was actually first observed in 1888.
This is a necrotic fungal pathogen that is not limited to a single host; it has plenty of hosts to choose from and actually is capable of infecting nearly 2,000 dicotyledonous species. With this being said, it is commonly found inhabiting the alkaline calcareous soils found throughout the Southwest region of the United States. Targeting dicots due to the fact that the majority of monocots are immune to it, you’ll see that it typically spreads throughout the dicot communities rather rapidly. Economically speaking, the plant hosts that this infects includes some of the most important economic species of plants around, including peanuts, alfalfa, apples, ornamental trees, cotton, and pecans.
Chlorosis of the leaves is usually the first sign that a plant has this disease. You’ll notice the browning and wilting of the plant’s leaves after this. Then, after around two weeks, the plant will die. Looking at cotton plants that have been infected, you’ll see that the wilting will usually happen during the mid to late summer time and when this occurs, it happens in large circular patches. It does not take long for these patches to die.
Wheat stem sawfly
The wheat stem sawfly is a North America native and is typically found throughout the grasses, primarily the wheatgrasses, as well as other grass family crops. These pests are found throughout a variety of host plants too. The wheat stem sawfly is an infestation insect that devours rye, triticale, some varieties of barley, and wheat. You’ll find that in the wheats, the spring wheat is typically the most common to be attacked. This pest has been bothering the crops found throughout North Dakota as well as Montana but it is not the biggest problem with the winter wheat yields due to the earlier maturing that these plants exhibit. It’s simply not the most attractive plant for these pests to lay their eggs. With this in mind, the larvae are not capable of completing their development prior to the harvest happening.
Even with this being the case, more recently we’ve observed winter wheat found in the northern plains having some serious damage caused by the wheat stem sawfly. The central High Plains was not being negatively impacted by these pests for quite some time and it is thought that the reason was due to the predominance of the winter wheat while the spring wheat was not being widely grown. Although that was the case at one point, the last twenty years we’ve observed some very bad infestations throughout the region and these infestations have even spread out towards Wyoming as well as adjoining counties found throughout Nebraska. With this being the case, we’re still unsure as to why the wheat stem sawfly has decided to become more commonly distributed throughout areas with winter wheat but the region is definitely suffering as a result of this increased presence. The most serious infestations of the wheat stem sawfly are seen in areas that have no-till wheat production so this pest is something that is rather new to this region.
Golden apple snail
The golden apple snail, or P. canaliculata, is native to come parts of Uruguay and Argentina. This is a freshwater snail that has steadily been increasing its population and distribution ever since it was first introduced to Asia. These snails were introduced mainly as a food resource but they’re also used in the aquarium trade. Their distribution globally began between 1970 and 1980 and upon being introduced to different areas, they began to spread without resistance throughout the bodies of water in the areas during floods. The result is these snails invading canals and rivers throughout the world.
Golden apple snails are voracious eaters and they feed on aquatic plants without hesitation. The rice fields throughout Southeast Asia are easily devastated by these invasive snails. Taro in Hawaii is also impacted negatively by these ravenous golden apple snails. Semi-aquatic crops are also known to be devoured by them as well. Native fauna is yet another food source of these snails. The snails also have numerous parasites that are known to cause human eosinophillic meningitis too.
These snails have also made the list showing the world’s most detrimental invasive species. Throughout the United States, it is illegal to transport the snails from state to state and it is also prohibited to transport them between islands found in the Hawaiian region. Malaysia and Japan both even have the golden apple snail placed on the quarantine list with the other quarantine pests. Australia is yet another country that voices its concerns over the golden apple snail epidemic, maintaining some seriously strong quarantine restrictions that are meant to protect its region from the invasive pests.
Adult golden apple snails have a thin and smooth shell that is between 35 and 60 mm tall. The coils in the shell are dextrally coiled and fully grown females are bigger than their male counterparts. They have a foot that is oval-shaped, possessing a square-shaped anterior edge, and it has long, tapering tentacles as well as a large, short eye.
Barley stripe rust
Barley has the potential to get a fungal disease called barley stripe rust. This fungal disease is the result of the barley coming into contact with Puccinia striiformis f. sp. hordei. The United States first found this stuff in 1991, but it wasn’t until 1993 that is was observed throughout eastern and northern Idaho. Barley stripe rust has also been found throughout the western areas of Washington and Oregon and since it was found, it has become rather established in these regions. The problem with this fungal disease is that it starts out at a small loci found in a field and does not take a long time to spread throughout regions, resulting in serious losses throughout the regions that have cool and wet climatic conditions.
When an infection happens in barley, you’ll notice that linear, orange-yellow pustules become obvious on the leaves and/or the heads of the plants. Over time, the disease becomes worse and the pustules coalesce to create stripes found between the leaf veins. You’ll notice that when it comes to the susceptible cultivars, the whole leaf blades have the potential to be coated with pustules. The stage that this progresses into black spores will develop once the entire leaf is coated with linear black pustules.
Barley stripe rust progression starts with not too many infections, meaning they’re not easy to find and sometimes impossible to see within a field full of barley. It’s not difficult for the pathogen to spread out, meaning the infestation has explosive potential that can cause some serious losses. This is especially true in areas where there is cool and wet weather, such as the Pacific Northwest region of the United States.
Managing this fungal disease is done by growing crops that are disease resistant. There are also times in which foliar fungicides are necessary when someone is growing some susceptible cultivars.
Cereal cyst nematode
Cereal cyst nematodes are pests that are found in graminaceous crops across the globe. These are a major problem throughout eastern Australia, but they are also found throughout the Central and Northern regions throughout Australia. These nematodes are becoming even bigger problems throughout the areas in which intensive cereal cropping is happening as well. Cereals and a variety of other grasses, wild oat, in particular, will get infected by cereal cyst nematodes. Some non-cereal crops act as a host to these nematodes as well, so it is advised that people should rotate for the purpose of limiting the amount of damage the cereals get from these pests.
When these nematodes infect an area, it’s easy to see their impact. Looking above the ground you’ll notice a lot of patches that are composed of stunted and yellowed plants. If a farmer plants a susceptible crop succeeding the infected crop, these patches will grow over time. Looking at the roots of the plants, you’ll also notice that there are some other symptoms. Under the ground, you’ll notice that the roots of barley and wheat will have a knotted appearance. With oat roots, the roots will look rope-like and swollen. The fact of the matter is that when cereal cyst nematodes are infesting an area, you’ll notice that the plant root system development will be shallow and retarded. Over the course of springtime, you’ll also see some white cysts appear on the roots as well. Simply dig up a plant, wash the roots of the soil, and you’ll see these cysts as they are around the size of the head of a pin. These white cysts are actually the swollen bodies of female cereal cyst nematodes and each of them has several hundred eggs ready to infest the area as soon as they hatch.
Sharka, or plum pox, is one of the worst viral diseases that occurs within stone fruit derived from the genus Prunus. The plum poxvirus, or PPV, is known to cause this disease and there are a variety of different strains that have the potential to infect various stone fruit species. These species of fruit include almonds, sweet and tart cherries, peaches, plums, nectarines, and apricots. There are also some ornamental and wild species of Prunus that can catch these infections depending on the strain of the virus that comes into contact with them.
Apids transmit this virus and these small insects move infected plant material from plant to plant. There is no danger associated with plum pox when it comes to people, but it has the potential to devastate farmers by ruining stone fruit as it makes them deformed and highly acidic. Managing this disease is done by annihilating all of the trees that have been infected with the disease, making the disease something that can really take a toll on the economy.
There are several types of aphids that will transmit this virus. These include the plum leaf curl aphid, the green peach aphid, and the plum-thistle aphid. It is possible for winged aphids to transmit the disease throughout an orchard as well as over short distances of between 200 and 300 meters. This can result in trees found in orchards within one another’s proximity to have the same sharka problem, causing mass devastation with farmers. This is not a disease that continuously persists within the aphids and as a result, the way it is transferred is through the mouthparts of the aphids and the plants. It is typically only possible for long distance spreading of this disease to occur when an infected nursery stock or propagative material is being moved.
Drywood termites are different from subterranean termites because rather than building their colonies in the soil, the drywood termites don’t have to have soil moisture. These termites are found in dry wood that can be above the ground. With this being said, the drywood termite colonies are built in structural wood, furniture, window frames, door frames, moldings, and utility and fence posts. Due to the fact that the termite workers are hard to identify, figuring out the species of the termite is usually done using the geographical location that they are found in. The southern areas of the United States are where these termites are typically found as they do not have the freezing temperatures that drive them away during the majority of the winter. There are times that some isolated drywood termite colonies will be noticed throughout the areas that are a little north of the southernmost region of the United States but the majority of the time, the drywood termites reside in the south.
With drywood termite colonies being built within wood, finding them is hard to do when conducting routine dry-rot and pest inspections. This being said, the best way to find an active infestation of drywood termites is to notice the fecal pellets. These pests will kick their fecal pellets out of their colony to avoid having them accumulate within it. With this known, the pellets will pile up underneath the infestation, highlighting where the colony is. The fecal pellets are easy to spot as they have a unique ridged shape and are around 1/25″ in length, or around the size of a grain of table salt. These fecal pellets are significantly larger than the ones subterranean termites make and the subterranean termites do not kick the dry fecal pellets out of their colonies like the drywood termite colonies do.
You’ll find that the subterranean termite is a pest that builds its own unique tunnels that people will sometimes call “mud tubes.” They build these tunnels to allow them to reach their food sources as well as protect themselves from being out in the open. Using their jaws like a pair of scissors, they eat wood consistently throughout the day. This is a 24-hour a day action that they commit to and they consume products that contain cellulose. With this being said, subterranean termites will swarm throughout the spring as the reproductive termites leave their colonies in an effort to begin new colonies elsewhere.
These termites are found living in their own underground colonies. The colonies can be as large as two million. You’ll also find these termites residing above the ground in areas that are moist and secluded. With this being said, there is good reason for them to want the seclusion. These are one of the detrimental termite species known to man. With their saw-toothed jaws being hard enough to tear through wood piece by piece without hesitation, it’s easy to see why people would want to harm them. They have the potential to collapse entire buildings and ruin homeowners financially simply by infesting the dwellings.
Preventing these termites from infesting your property is possible but it takes an effort. The best known way to control subterranean termites is to make sure water does not accumulate anywhere near the foundation of your home. Make sure to divert any water away from the property using downspouts, splash blocks, and gutters. Also, you’ll want to reduce the humidity found in your crawl spaces by utilizing the proper ventilation to keep it nice and dry. These termites hate dry areas. You should make sure to avoid burying any wood scraps or lumber waste in your yard as well. Do not allow any wood to contact the soil around your home and maintain a minimum of a one-inch gap between the wood of the building and the soil.
Citrus longhorn beetle
Found naturally residing throughout China, Korea, and Japan, the citrus longhorn beetle is a pest that has the potential to seriously impact the environment. Every one of the female citrus longhorn beetles has the potential to lay as many as 200 eggs once they mate. After mating, the eggs are separately placed inside of tree bark and once the beetle larvae hatch, it begins to chew into the host tree. The tunnel that it creates is then utilized for the beetle to continue growing from its larval state into an adult. It takes between twelve and eighteen months for the adult citrus longhorn beetle to mature from an egg.
These beetles have some seriously negative impacts on the areas they infest. They are capable of killing numerous different kinds of hardwood trees making them a pest that farmers truly hate. They can infest pecan, apple, hibiscus, Chinaberry, poplar, litchi, kumquat, oak, Ficus, Japanese red cedar, pigeon pea, mulberry, pear, willow, sycamore, Australian pine, and citrus trees.
While there were several times that these beetles have been observed in the UK, the United States is where the real infestation problem resides. The citrus longhorn beetles impact the environment in North America due to the fact that it attacks the healthy trees there and without any natural enemies, they are free to spread out without getting eaten. There are various types of plant areas being impacted, including urban landscapes, backyard trees, greenbelts, forests, orchards, and wildlife habitats. They were first seen in the United States back in April of 1999. It was a single beetle found in Athens, Georgia in a nursery greenhouse on some of their bonsai trees that had been imported from China. A few years later in 2001, the beetles were found in a Tukwila, Washington nursery amidst a shipment of 369 bonsai maple trees that came from Korea.
Red ring disease/Pine wood nematode
The pine wood nematode is known to infect pine trees and result in the disease called pine wilt. This is known to occur throughout a lot of the United States, Mexico, and Canada, but it’s also seen occurring throughout Portugal, Japan, Korea, Taiwan, and China. The pine mortality first was observed and reported in Nagasaki, Japan in 1905 while the first one that was seen in the United States happened in Louisiana in some timber of longleaf pine. This was seen as a new species in the United States and it was in 1934 that it was named Aphelenchoides xylophilus.
By 1969, Tomoya Kiyohara and Yozan Tokushige, a couple of Japanese plant pathologists, found that there were actually a lot of unfamiliar nematodes on some dead pine trees found throughout the Kyushu islands. With this being known, they began to experiment on the nematodes to find how they could vaccinate the trees. They found that while the Japanese red and Japanese Black pine were killed by the nematodes, Sugi cedar, Hinoki cypress, and Jack and Loblolly pine trees lived with the pests. With that said, they came to the conclusion that this pathogen was the culprit that was killing Japanese pine trees.
Pine wood nematodes have a normal nematode life cycle that contains four juvenile stages as well as an adult stage. These occur within males and females. They also reproduce sexually. With this in mind, the mycophagous phase of their life cycle happens in dying or dead wood. This is where they are capable of living and feeding on fungi as opposed to the wood. They are incapable of traveling outside of their wood abodes by themselves and have to get transported by hitching a ride with an insect. In essence, the pine wood nematode cannot move without some sort of insect vector.
One wilt fungal disease, Fusarium wilt, showcases symptoms that are comparable to those of Verticillium Wilt. Fusarium oxysporum is the pathogen causing this wilt fungal disease and depending on the host plant, it is a species that is split up into forma specialis. There are many different hosts that Fusarium wilt is capable of impacting. These include but are not limited to tobacco, tomato, cucurbits, legumes, banana, and sweet potato. With this in mind, there are other susceptible plants and it is known to infect many other herbaceous plants as well.
The symptoms that are produced by F. oxysporum include chlorosis, wilting, premature leaf drop, stunting and damping of, browning of the vascular system, and necrosis. That being said, the most devastating impact that this fungal disease has is vascular wilt. With Fusarium wilt, you’ll notice it begins the veins becoming clear on the younger leaves and the older lower leaves will begin to sag. After this, you’ll see some stunting and yellowing of the plant’s lower leaves, marginal necrosis, defoliation, and then, the death of the plant. The older plants have symptoms that are rather distinct when they occur between the blossoming time and time of fruit maturation.
You’ll see that F. oxysporum is usually found in soil saprophyte and it infects many different types of host species found across the globe. It is a very durable disease, having the capability of surviving throughout a multitude of soil types, including tropical, desert, non-cultivated, cultivated, and even arctic soil. While it can be found throughout a multitude of habitats, the disease is known to favor higher temperatures and warmer moistened soils for prime development conditions. Its preferred temperature to grow on artificial media ranges from 25 to 30 degrees Celsius while the prime soil temperature for root infection is 30 degree Celsius or high. Infection through seeds is possible at temperatures that drop all the way down to 14 degrees Celsius.
Sugarcane stalk borer
Sugarcane stalk borers are larvae that creates tunnels throughout sugarcane stalks or stems and the resulting damage that comes with these pests is unbelievable. With the larvae tunneling inside of these cane stalks, they tend to hurt the meristem. This has the potential to kill the plant. The dead tops or dead hearts that sugarcane stalk borers result in are a serious issue throughout Louisiana in the United States. This is usually occurring in the younger cane but there are times in which these pests affect the older plants as well.
Looking at the commercial varieties that are grown results in an understanding that they are capable of tolerating as much as 33 percent of a reduction in young shoots prior to the yield loss becoming an issue. With this being said, the yield can be significantly lessened as a result of sugarcane stalk borers and this can result in the stalks becoming more likely to get broken by gusts of wind or over the course of the harvest season. The yield and weight of the cane are capable of being reduced as a result of these pests as well as they consume the plant tissue and retard the growth by way of severing the nutrient flow to the top portion of the stalks. The quantity of the cane juice is also lessened, as is the sucrose the plant is capable of producing. We’ve witnessed sugarcane stalk borers impact the purity of the cane just as well as they lessen the amount of ash, gums, sugars, total organic non-sugars, and alcohol-perceptible non-sugars. Also, if the damaged stalks are infested with micro-organisms such as red hot and other fungi or bacteria, there is some other serious damage that can occur in relation to both the yield and juice the stalks produce.
As a leaf-spot disease found infecting banana plants, Black Sigatoka is something that is brought on by the ascomycete fungus Mycosphaerella fijensis, or Morelet. This disease is also called black streak leaf and following its discovery back in 1963, the name was given to it as it is rather similar to the yellow Sigatoka that Mycosphaerella musicola, or Mulder, causes. With this other disease in mind, it got its name from the Sigatoka Valley found in Fiji following an especially nasty outbreak of Yellow Sigatoka that caused an epidemic over the course of 1912 throughout 1923.
When this disease occurs within a banana crop, the pathogen results in some streaks that run parallel to the lines on the leaves. This is an ascomycete fungus that has a negative impact on the banana trees that are found throughout the tropical climates of the world. These regions include West Africa, South America, China, and Asia. With this being said, the tropical weather is what the banana trees thrive in just as it is the environment that supports the pathogen’s thriving. The hot and humid weather combined with a lot of rainfall assists with spreading the fungus around as well. Mature banana leaves are infected by the fungus and the infection continues if the proper measures are not taken.
When the plant is first infected, you’ll notice that the lesions found on the banana plant start becoming a rusty brown and it looks as though there are light-colored specks on the leaves. Over time, the visibility spreads to the banana leaf undersides as a result of the lesions and leaves growing. Those spots found on the leaf undersides are composed of the fungus. You’ll know that the pathogen is there when the ascocarp that is holding the ascospores begins infecting other healthy plants if the environment allows for it.
Potato late blight
With this disease being capable of spreading fast from field to field when the weather conditions allow for it, late potato blight is sometimes called ‘the community disease.’ Potato late blight is world renowned for being a seriously detrimental disease in relation to the agriculture industry. Looking at the history of this disease results in an understanding that it was the cause of more than 2 million people either dying in or having to flee Ireland as the Irish potato famine occurred throughout the 1840s. With this disease came the need for the plant pathology field, resulting in countless studies. There were studies conducted to gain an understanding of this disease and over the course of them, Anon deBary, a botanist, found that late blight was causing this fungal-like growth. With this being said, deBary’s work pushed other scientists to begin investigations relating to various other kinds of fungi and bacteria that relate to plant disease. With Koch’s postulates for showcasing pathogenicity, it became possible to identify the pathogens that cause a lot of plant disease.
Phytophthora infestans, oomycete pathogens, cause potato late blight. While this is the main pathogen associated with tomatoes and potatoes, there have been a lot of causes in which it will infect various other plants found in the Solanaceae family too. One of the major qualities it has is it being in possession of both a sexual and an asexual life cycle. While they typically will produce asexually, we’ve observed a sexual cycle occurring in some places throughout the world, such as Mexico. It produces mainly asexually in the United States, but sexual reproduction happens in this country as well. With this being the case, outbreaks that occur throughout the United States are capable of being identified as a component of clonal lineage, allowing them to be highlighted based on certain qualities they possess, including fungicide sensitivity and aggressiveness.
The sunn pest is a bug from the same family that you’ll notice a multitude of genera of the stink bug and the shield bug in. One species, Eurygaster integriceps, is the one that holds the most economic significance. With this being said, the sunn pest is distributed throughout parts of North Africa, a lot of the newly independent states that are found in Central Asia, and West Asia.
These insects are known to have major impacts on barley and wheat throughout West Asia. With this being said, the region spends in excess of $42 million controlling these bugs every year. Looking at the amount of yield that is lost as a result of the damages these pests cause results in the knowledge that between 50 and 90% of wheat is lost while 20 to 30% of the barley is lost. These damages come in the form of the sunn pests consuming stems, grains, and leaves. Over the course of their consumption, they inject chemicals that damage the wheat to a point that the flour no longer has the same baking quality. With this said, if between 2 and 3 percent of the grain is harmed, the result is devastating as it has the potential to ruin the flour, making it so the bread cannot rise and the taste is off. When the sunn pests attack wheat for extended periods of time, the wheat stems will break prior to the harvest as well.
There are big regions in which the wheat cannot be harvested as a result of the damage the sunn pest incurs. While they attack barley, the damage they cause is typically lower than the damage they cause with the wheat. With this being said, these pests will usually have a big outbreak every 6 to 8 years, resulting in yield losses that can range in the tens of millions of dollars!
Western/Tarnished plant bug
Tarnished plant bugs, or Lygus lineolaris, is a member of the Miridae family. These are plant-feeding insects that use their piercing sucking mouthparts to ravage fruits and vegetables throughout the North American region. With this being said, it is seen as a species that is seriously polyphagous as it consumes more than half of all of the crop plants people grow commercially. These insects prefer to consume stone fruits, conifer seedlings, cotton, beans, and alfalfa.
While the tarnished plant bug will feed on many commercial crops found in North America, they are primarily observed eating weeds and young apples. They’re also an insect that uses a relatively unique style of feeding called lacerating and flushing. Through this eating strategy, the bugs utilize sucking mouthparts as a means of injecting saliva into the host plant it is consuming. The tarnished plant bugs have a saliva that includes polygalacturonase, an enzyme that is known to degrade plant tissue. It also contains pectin for the purpose of breaking down the cell walls, letting them digest the plant tissue faster. In essence, these bugs are capable of consuming and digesting plant matter at a fast rate.
There was a study conducted in the southwestern region of Quebec, Canada that was meant to showcase the presence of the tarnished plant bug in a commercial vineyard. Wit this study, it was observed that the weeds grown as a result of the cultivation of crops acts as a primary food source for these insects. They’re found throughout the North American region stretching from southern Mexico all the way to northern Canada. Identifying these insects is not difficult as they are rather unique looking. The adults will grow as large as 6.5 mm long and have a brown color highlighted by the accents of red, orange, and yellow. There is also a light-colored “V” found on their backs.
Exotic sawyer beetles
Exotic sawyer beetles are known for burrowing deep into the trunks of trees but the trees are usually either recently deceased or stressed, such as the pines that have pine wilt disease. These insects are borers. With this being said, they’re also called longhorned beetles due to their antennae being a minimum of half of the length of their bodies. At times, their antennae can be even longer. These bugs have a variety of species but even with this being the case, aesthetically speaking, they typically have a smooth, streamlined shape to them that tapers as you get closer to the back of them. They’re usually drab black, brown, or gray. Some of them have a look that seems to resemble a wasp, or a banded pattern containing black and orange or yellow or a variety of other colors.
The bugs start out as larvae. These larvae are grub-like and pale in color. You’ll typically find them inside of plants or wood. As they grow, the beetles eventually emerge and they get from 1/8 of an inch to 2.5 inches in length. A lot of them are around ½ an inch but it really varies depending on the species.
As larvae, the majority of the species of exotic sawyer beetles will eat wood as they live within a tree. A lot of them will bore into dying, rotting, or dead wood, but there are times that they will consume living trees. Many exotic sawyer beetle larvae will tunnel underneath the bark found on the limbs of the trees. This results in a severed vascular system of the tree’s limb that will cause the limb to dye. The dying tissues are them consumed by the sawyer beetle larvae. While trees are typically targeted, there are some species that reside in the soil and consume roots. As adults, most exotic sawyer beetles devour sap, fungi, bark, leaves, and flowers while some of them will only consume water.
European canker is an infection that occurs in plants and when it is noticed, it is imperative to take care of it immediately. The fact of the matter is that leaving infections untreated has the potential to allow for the spreading of European canker, meaning when there is an infection, one of the immediate actions that must be taken is to remove the canker infection or perhaps even entire infected trees.
If there is a sign of European canker ravaging someone’s plants, a canker management plan comes out of necessity. When a person does not come up with a plan like this, the infected trees and even entire orchards are at risk. This pest takes a long time for it to build up and with this being the case, it also takes a long time for them to get put under control.
The cause of the European canker is a fungus by the name of Neonectria ditissima. It gets within trees by attacking fresh scar tissue or wounds. This can include winter pruning, leaf fall, harvest time, summer pruning and thinning, petal fall and fruitlet drop, and bud break (because the bud scales open and fall). You’ll notice with these infections you get some white spores that are within the European canker cracks. This occurs with conditions found in the autumn, summer, and late spring. With this being said, as soon as the spores land upon some sort of open wound on a tree, they infect it. These spores spread with rainwater splashing.
There are several ways to manage European canker if it is infesting your orchard. One way is to make sure you walk throughout the orchard every month over the course of the season. Another strategy to pursue is monitoring any known points of spread by marking the infected trees. As time passes, use different colored tape or paint for every season to mark the trees that still show symptoms. Also, remove and burn any visible cankers or lesions throughout the year.
Dutch elm disease
Ascomycota is what causes Dutch elm disease and with this disease infecting elm trees and being spread by the infamous elm bark beetle, it’s easy to see how this disease is a major concern. While it is thought to be derived from Asia, this disease was introduced to both Europe and America by accident, resulting in some truly devastating effects on the native elm tree populations. These populations do not have any resistance to Dutch elm disease, making it extremely problematic. Furthermore, this disease has made its way to New Zealand.
Currently, Dutch elm disease is being spread throughout North America by three bark beetle species. These include the native elm bark beetle, the banded elm bark beetle, and the European elm bark beetle. While these beetles spread the disease, there is some field resistance occurring.
There are several factors that allow elms to bypass the Dutch elm disease as opposed to trying to survive the disease. The European White Elm Ulmus laevis does not possess much genetic resistance to Dutch elm disease. With this being said, the trees synthesize a triterpene called Alnulin to ensure that the flavor of their bark is no longer attractive to vector beetles. This results in the beetles passing over them in search for elms with bark that is more palatable.
These trees also try to ensure that Dutch elm disease cannot spread to other plants. They do this by plugging their own xylem tissue with tyloses and gum. These are extensions of the xlyem cell wall that are comparable to a bladder. The xylem is known for delivering water and nutrients throughout the plant but with these plugs, they cannot travel throughout the tree’s trunk. Eventually, these plugs make it so it cannot travel throughout the tree’s trunk and this results in the successful killing of the fungus.
- Asian Longhorned Beetle
- Brown Marmorated Stink Bug – Stop BMSB Website
- Brown Marmorated Stink Bug ( Pest Alert PDF)
- Emerald Ash Borer (PDF)
- Lobate Lac Scale (PDF)
- The Multicolored Asian Ladybeetle
- Pink Hibiscus Mealybug
- Ralstonia solanacerum (PDF)
- Soybean Aphid
- Soybean Rust
- Spotted Wing Drosophila (PDF)
- Sudden Oak Death
- Tospoviruses (PDF)
- West Nile Virus
- Woodboring Insects (PDF)
The Western IPM Center is headquartered in the UC Agriculture and Natural Resources Building at 2801 Second Street, Davis, CA 95618.