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Apply fungicide before Tar Spot finds a place in your corn field.

Corteva Agriscience | Aug 15, 2022

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Tar spot is top of mind for many Corn Belt farmers. Caused by the fungal pathogen Phyllachora maydis, tar spot reduces yield potential by affecting the photosynthetic capacity of leaves and causing rapid premature biological aging or leaf senescence.

Initial symptoms include small brown lesions that darken with age. Early signs of tar spot can be mistaken for insect feces. Tar spots (stroma) are embedded in leaf tissues and are often visible on the underside of the leaf. The texture of the leaf often becomes bumpy and uneven when the fruiting bodies are present. This foliar disease may be difficult to find if infections develop in patches in the middle of a field.

Related: Quick Take: Big Bud at FPS, new checkoff boards, field days

“Tar spot scouting begins with looking into the canopy and using the sun to look for shadows on the underside of the leaves,” said Kevin Fry, a Pioneer Field Agronomist in Pennsylvania.

Ideally, a fungicide application should be made before tar spot is firmly established. Once identified, tar spot can be difficult to stop. Applying fungicide between VT and R4 can help keep tar spot at bay.

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For fields with a history of tar spot, a second fungicide application later in the season can offer additional protection. Duration of leaf surface wetness appears to be a key factor in the development and spread of the disease. Scouting fields after rain events can help growers spot tar spot sooner.

“Tar spot will persist with the wet, humid weather,” Fry said. “Growers should continue walking their fields and looking for tar spot.”

Source: Corteva Agrisciencewho is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset. 

TAGS: FUNGICIDE CORN, SCOUTING, MANAGEMENT, DISEASE, CROP DISEASE

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Armyworms inactive despite rain, cool front

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Fall armyworms can be devastating to hayfields and pastures due to their appetite for green grass crops.

Texas Crop and Weather Report – June 2, 2022

Adam Russell | Jun 03, 2022

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Texas forage producers are facing high fertilizer prices, but Texas A&M AgriLife Extension Service experts do not expect they will face an early outbreak of fall armyworms.

David Kerns, AgriLife Extension state integrated pest management specialist and professor in the Department of Entomology, said recent weather has not created conditions for the early migration of the devastating pest experienced in 2021.

Populations typically build following large rain events and cooler weather. But Kerns said there is no indication that armyworm populations are building in southern areas of the state following recent weather systems that dropped temperatures and delivered moisture.

Fall armyworms’ name is indicative of their active season, but cool, wet weather can trigger outbreaks, Kern said. Populations of armyworms, which are extremely damaging to forage production, typically begin increasing sometime between July and September.

“Fall armyworms typically build up in southeastern Texas, and the moths move northward throughout the eastern half of the state,” he said. “Last year, with all the spring and summer rains, that buildup occurred earlier than usual, but conditions are much drier this year despite the recent storm fronts.”

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No reports of armyworms so far

Fall armyworms are green with brown or black colorations and can be identified by the white inverted Y on their head. They can grow up to 1 inch in length when mature.

The pest got its name because they appear to march army-like across hay fields, consuming the grass in their path.

Armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a 2019 report by Allen Knutson, AgriLife Extension entomologist, retired.

Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton, said there are four to five generations that move throughout the state per growing season. They typically move north from Mexico and South Texas as temperatures warm in the spring. Generations will push further north into midwestern states, but moths and larvae remain present throughout the state.

Drier, hotter conditions slow their life cycles, Corriher-Olson said. Moths lay fewer eggs and caterpillar growth is slowed. But rainfall and cooler temperatures can trigger major infestations when local populations, new hatches and migrating moths descend on areas with quality food sources.

Corriher-Olson said continued drier conditions overall in southern parts of the state are likely to curb any early issues forage producers may have experienced in 2021.

“I have not received any reports or phone calls, and that tells me populations in areas where the armyworm migration begins have not reached any level of concern,” she said.

No problem until there is a problem

Corriher-Olson said producers typically react to fall armyworm outbreaks when they occur, which has led to product availability issues during the pandemic. She noted, however, that she had not received any reports about insecticide shortages to date.

“Many producers take a reactionary approach to armyworms because of the expense,” she said. “Some producers may have products on hand that are left over from last year, but most are going to be monitoring the situation to their south and plan accordingly.”

Kerns said conditions may not be shaping up for armyworms at this point in the forage production season, but producers with Sudan grass, hay grazer and other forages related to sorghum should be on the lookout for sorghum aphids, also known as sugarcane aphids.

While armyworms prefer wetter, cooler weather, sorghum aphids prefer hot, dry conditions, he said. There have been reports of the aphids in grain sorghum fields in South Texas.

Aphids feed on leaves and leave a sap that further damages the plant, and major infestations can greatly impact forage yields.

Corriher-Olson said forage pests like fall armyworms and aphids are always a threat to producers’ bottom lines, but yield losses could magnify their impact on budgets due to higher input costs, especially fertilizer applications.

Many forage producers are forgoing or reducing fertilizer applications, which could impact where infestations build, she said. Fall armyworms will settle on any green pasture, but they prefer lush, fertilized forages.

“Fertilized fields are more at risk to be damaged,” she said. “So, when it comes to armyworms, we don’t want to see a producer spend money to produce quality forage and have armyworms destroy it.”

AgriLife Extension district reporters compiled the following summaries:

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The 12 Texas A&M AgriLife Extension Districts

ROLLING PLAINS

Rainfall amounts were from 1.5-3 inches. The rains helped the soil moisture profile, but more rain was needed to fill stock tanks. There was very little green grass in pastures. Wheat harvest continued in the little bit of wheat worth combining. Yield reports ranged from 3-25 bushels per acre. Supplemental hay feeding of cattle continued.

COASTAL BEND

Southern parts of the area reported showers that produced trace amounts to 2 inches of rain. Crops with irrigation looked good, but dryland producers were concerned about crop losses. Cotton benefitted the most from rain, but more moisture will be needed to see good yields. Corn and grain sorghum were drying down and any moisture would probably only help with the kernel weight. Rangeland and pastures showed a slight color change with rain, but not much growth occurred, and conditions remained poor to fair. Livestock were still in a decline and receiving supplemental feed. Hay supplies were dwindling. More cattle producers were weaning early and culling out poor producing cows. Cattle market prices remained high.

EAST

Recent rains helped, but soils dried quickly. Pasture and rangeland conditions were fair. Subsoil and topsoil conditions were short to adequate. Hay production continued. Yields were much lower than normal as producers reduced fertilizer applications due to higher input costs. Harrison County reported problematic fly populations. Livestock were in fair to good condition.   

SOUTH PLAINS

Producers received another significant rainfall shower this week across the county. Rainfall totals ranged from 0.5 inches to 2 inches. Some large hail was also mixed with the heavier rain. Cooler temperatures helped conditions. Rain was in the forecast. Cotton planting was in full swing with about 80% of acres planted so far. More rain will be needed for decent cotton, corn and sorghum yields. Pumpkin farmers started planting. Cattle were being supplementally fed. The recent rainfall helped pastures a little.

PANHANDLE

Soil moisture conditions were very short to short. Recent rains helped irrigated crops like wheat, corn and cotton some. Earlier planted corn was up and growing, but some silage corn plantings were still on hold. Cotton was already planted or going in, but producers were not optimistic about yields. Rangeland and pasture conditions improved, but much more rain will be needed to sustain a green-up. Overall, rangeland and pasture conditions remained poor, and crop conditions were poor to fair.

NORTH

Soil moisture ranged from adequate to short. Warmer temperatures and higher wind speeds dried up soil moisture. Corn, cotton and soybeans were doing well. Early planted corn was tasseling. The wheat harvest began, and fields looked good. No widespread insect or disease pressure was reported. Pasture and rangeland conditions were fair to good and had improved slightly following recent rainfall. The first hay harvests of Bermuda grass, ryegrass, Bahia grass or oats were cut and rolled without issue this year. This was the first early forage harvest in the past few years not delayed by rainfall or wet conditions. Cattle were in good to excellent condition. Horn and stable flies were increasing significantly, and horseflies and deerflies were worsening. Spring calves appeared to be gaining well. Supplemental feeding continued for livestock and wildlife, and forage quality looked poor. Rainfall will be necessary for continued forage production. Some hay producers were considering transitioning pastures to native forage production due to lack of rain and increased fertilizer costs.

FAR WEST

Weather was variable. A cold front dropped temperatures into the 40s and brought rainfall, hail and dust storms that took visibility to zero, but temperatures quickly returned to the 90s. A very narrow band of storms left trace amounts of rain up to 1.5 inches. Hail damage to farm equipment, barns, trees and residences was severe. Emerged cotton was hailed out. Cotton, especially Pima fields, looked good in other areas. Corn continued to make progress, but heat was starting to take its toll. Melons looked good and were making good progress. Pecan trees were coming along nicely and set a good crop. Some pecan nut casebearer pressure was reported. Alfalfa looked decent. Pastures remained completely bare. Cattle conditions continued to worsen, and some ranchers completed weaning.

WEST CENTRAL

Thunderstorms delivered from 1.5-3 inches of rainfall to most areas. Forages perked up with the moisture, but temperatures in the 90s and windy days could impact moisture retention. Some farmers harvested wheat last week, but yields were poor. Cotton outlooks were looking slim as well. Herd liquidation was slowly happening. Some producers with hay chose to feed through drought, but many were selling off their herds. An ongoing wildfire near Abilene was under control, but not before it burned 10,900 acres.

SOUTHEAST

Heavy rains helped soil moisture levels. Some hay was cut, and rice was fertilized. Forages were growing and producers in several areas cut their first hay crop with no pests reported. Rains slowed crop planting in some areas. Rice planting was not complete. Some areas remained dry and reported declining pasture, rangeland and crop conditions. Rangeland and pastures ranged from very poor to excellent condition. Soil moisture levels were short to surplus.

SOUTHWEST

Some areas received 0.75-3 inches of rain. The rainfall helped alleviate the drought stress for crops that survived to this point. Hot temperatures persisted and pastures looked overgrazed. Wheat and oat harvests were complete with below-average yields reported.  Irrigated corn looked good, and cotton was doing well. Producers eased up on supplemental feeding due to the recent rains, but pasture conditions continued to decline in drier areas. Mesquite spraying was underway. Diet supplementation continued for livestock and wildlife, and forage production looked poor. Irrigated hay fields were in good condition.

SOUTH

Moisture levels in northern areas were very short, while eastern and western areas reported short to adequate soil moisture. Southern areas reported adequate to surplus moisture. Most areas reported rainfall with amounts ranging from 0.3-8 inches. Pastures and rangelands responded well to the moisture. Livestock conditions were improving and producers were decreasing supplemental feed. Cattle prices remained strong. Cattle producers in drier areas continued to provide supplemental feed to maintain body condition scores. Producers who planted hay grazer before the rains were expecting good growth. Significant rain missed croplands in northern parts of the district. Row crops and forages in areas that received rain were expected to improve significantly. Irrigated crops like watermelons, cantaloupes and Bermuda grass looked good. Cotton was expected to respond well to the moisture. Flooding and hail damaged some crops. Hail damaged around 5,000 acres of grain, sesame, sunflowers, watermelons and corn. Sorghum aphid pressure increased, and weeds were becoming an issue as fields were too wet to spray.

Source: is AgriLife TODAY, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

TAGS: FORAGE FALL ARMYWORMS

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Mite-y Waist: Correcting a 60-Year Error in Mite Morphology

ENTOMOLOGY TODAY  LEAVE A COMMENT

Much of mite biology is clouded in mystery—even the delineation of their body segments. A new study upends a 60-year-old model for the proper location of mite “waists.” Shown here is a scanning-electron microscope image of a Proteonematalycus wagneri female mite. (Image by Sameul Bolton, Ph.D.)

By Samuel Bolton, Ph.D.

Samuel Bolton, Ph.D.

Most people are surprised to find out that mites live in more places than just inside their mattress or on their pets. But what we acarologists know about mites is, comparatively speaking, not so much more, for there is still a tremendous amount that we have yet to discover about these arthropods.

For example, our knowledge of global mite biodiversity is so meager that estimates of the total number of undescribed species of mites range across nearly two orders of magnitude—from 500,000 to 40 million. And our ignorance extends to some fairly basic aspects of mite biology. There are still competing ideas over the correct body plan for all mites. (See video, below.)

There is even a controversy over where one major body region ends and another begins. This particular controversy interests me because it illustrates how an influential idea can persist long after evidence comes to light that shows it is likely in error. When a bad idea becomes highly influential, often because the originator is influential or because the idea has aesthetic appeal, it can endure for long enough to become entrenched within the culture of a scientific community.

Mites are arachnids, and that means that they have a body that is divided into a prosoma (the limb-bearing region at the front) and opisthosoma (the limbless region at the back). To keep things simple, I will call the border between the prosoma and the opisthosoma the “waist.” This is apt because in most arachnids there is a waist-like constriction between the prosoma and opisthosoma, which makes it very easy to tell where the prosoma ends and the opisthosoma begins. But almost all mites lack such a visible waist.

In 1963, a well-known acarologist, Leendert van der Hammen, published a hypothesis on where the waist is positioned in mites. He proposed that the waist is delineated by a furrow, present in some mites, that runs obliquely from the top of the body to an area just behind the rear pair of legs (see Figure 1, top). However, there are other mites, such as Micropsammus, that have a body with a vertical furrow that looks a lot more like a waist (see Figure 1, bottom). The dorsal part of the vertical furrow is in a different segmental position to that of the oblique furrow. It is therefore not possible that the vertical furrow has reorientated to become the oblique furrow or vice versa, and so only one of these furrows can be the waist.

A model of a mite (top) shows the oblique furrow that Leendert van der Hammen thought was a “waist,” or the division between prosoma (the limb-bearing region at the front) and opisthosoma (the limbless region at the back). The image of a Micropsammus sp. mite (bottom), however, has a vertical furrow that looks a lot like a waist. (Image by Sameul Bolton, Ph.D.)

Most acarologists treat van der Hammen’s oblique furrow as the true waist. However, van der Hammen’s interpretation was based on oribatid mites, which have highly modified morphologies for defense, and so the oblique furrow seems more likely to be the result of a defensive modification than a true waist. Why, then, is his interpretation still widely accepted? One reason is that this is another example of a persistent and influential idea that is long overdue for retirement. Another reason is that almost all species of mites lack visible body segments. The waist is a segmental border that divides the prosoma from the opisthosoma. Without a series of clearly delineated segmental borders, it is difficult to know which of the two furrows is definitely a waist.

There is one mite, however, that does very clearly show its body segments, especially on the part of the body where the waist is. Proteonematalycus wagneri, which has been collected on no more than a handful of occasions, has been examined only very rarely. The description of P. wagneri, which is more than 30 years old, includes drawings of a segmented body that starkly contradicts van der Hammen’s interpretation. Drawings can sometimes be misleading, though. In a paper published in February in PLOS ONE, I analyze new detailed images of P. wagneri, which more clearly illustrate the flaw in van der Hammen’s hypothesis and offer a new model for mite body segmentation.

As seen in this image of a Proteonematalycus wagneri adult female mite, the oblique furrow is absent and so it cannot be the true waist. (Image by Sameul Bolton, Ph.D.)

The image in Figure 2 shows that P. wagneri has a segmental border that is in exactly the correct position and orientation to correspond with the vertical furrow of Micropsammus (Figure 1, bottom). That border is the true waist, not only because it divides the prosoma from the opisthosoma, but also because there is no sign of the oblique furrow. If you can clearly see the body segments but the oblique furrow is nowhere to be seen, that can only mean that the oblique furrow does not correspond with a segmental border, and so van der Hammen was clearly wrong about that furrow being the waist.

But why is it so important to know where the waist is? Well, as I mentioned above, the waist delineates the boundary between two major body regions, the prosoma and opisthosoma. If the oblique furrow were the true waist, it would mark out mites as very unusual compared to other arachnids. In an important way, Proteonematalycus wagneri shows that mites are not quite as weird as we had thought.

In fact, the position of the waist was correctly determined more than a century ago . But over the past half century, countless papers, including my own, have mislabeled characters as opisthosomal when they are prosomal. Almost 60 years of confusion and debate, all caused by one very influential paper that was written by one very influential acarologist. Oh, what a mitey waist.

Read More

Proteonematalycus wagneri Kethley reveals where the opisthosoma begins in acariform mites

PLOS ONE

Samuel Bolton, Ph.D., is curator of Acari at the Florida State Collection of Arthropods, in the Florida Department of Agriculture and Consumer Services’ Division of Plant Industry. Email: samuel.bolton@fdacs.gov.

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Crop leaf disease identification based on ensemble classification

Livestock and horticulture are well-known contributors to the global economy, particularly in countries where farming is the sole motivation for income. Yet, it is regretful that infection degeneration has affected this. Vegetables are a significant source of power for people and animals. Leaves and stems are the most common way for plants to interact with the surroundings. As a consequence, researchers and educators are responsible for investigating the problem and developing ways for recognizing disease-infected leaves.

Growers everywhere across the world will be able to take immediate action to avoid their produce from getting heavily affected, so sparing the globe and themselves from a potential global recession. Because manually diagnosing ailments might not have been the ideal solution, a mechanical methodology for recognizing leaf ailments could benefit the agricultural sector while also enhancing crop output. The goal of this research is to evaluate classification outcomes by combining composite classification with hybrid Law’s mask, LBP, and GLCM.

The proposed method illustrates that a group of classifiers can surpass individual classifiers. The attributes employed are also vital in attaining the best findings because ensemble classification has demonstrated to be much more reliable.

Read the complete research at www.researchgate.net.

Kaur, Navneet & V, Devendran & Verma, Sahil. (2021). Crop leaf disease identification based on ensemble classification. 

Publication date: Fri 10 Dec 2021

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From Mapping to Management: A Revision of Soybean Caterpillar Pest Information for U.S. Soybean

ENTOMOLOGY TODAY1 COMMENT

Lepidopteran pests of soybean—such as the green cloverworm (Hypena scabra), shown here—are growing in importance in the U.S., and a pair of articles in the Journal of Integrated Pest Management provides updated guidance on biology, distribution, and management options for five leading caterpillar pests of soybean. (Photo by Adam Varenhorst)

By Erin Hodgson, Ph.D., and Anders Huseth, Ph.D.

Anders Huseth, Ph.D.

Erin Hodgson, Ph.D.

There never seems to be a dull summer when you’re an extension entomologist of field crops. Like Coolio said, there is always “sumpin’ new” happening in agriculture. Fluctuating pest populations and invasive species make our jobs interesting. Add in new chemistries and technology updates, and it’s hard to keep up with everything.

When a pest does establish and become a problem, we want to provide accurate identification and timely management recommendations. Unfortunately, many of our tried-and-true resources are becoming out of date. New extension folks have been especially frustrated by a lack of current resources. In particular, there is not enough current information on caterpillars feeding in soybean, though these pests are becoming more economically important in the U.S. and around the world. So, a few of us decided to create an update for some of the most prominent species in U.S. soybean. We represent five states spread across the nation: Florida, Iowa, Louisiana, Minnesota, and North Carolina.

caterpillar pests of soybean
corn earworm (Helicoverpa zea)
thistle caterpillar (Vanessa cardui)

To start, we surveyed field crop entomologists in all soybean-growing states to better understand current pest occurrence and abundance in soybean (approximately 83 million acres). We compiled data from all 31 soybean-producing states during the winter of 2020. Data indicated five species that consistently bubbled to the top of the list: green cloverworm (Hypena scabra), soybean looper (Chrysodeixis includens), corn earworm (Helicoverpa zea), velvetbean caterpillar (Anticarsia gemmatalis), and painted lady (Vanessa cardui, also known as thistle caterpillar in its larval form).

After summarizing survey information, we decided to write profiles on these species to improve identification, distribution, and scouting guidelines. Our group used older research and recent field observations to develop profiles of these key pests. Last, we wanted to focus on management, especially highlighting insecticide resistance issues starting to become prominent in some states. The results of this work are shared in two articles published earlier this year in the Journal of Integrated Pest Management—one on identification and biology and another on distribution and population persistence—with a third article still in the works.

Results from our survey provide a contemporary assessment of distribution and persistence of lepidopterans in soybean. Like the aforementioned rap artist says, field crop extension entomology is a “fantastic voyage,” and we hope the articles help provide updated information for caterpillar identification and management.

Read More

Identification and Biology of Common Caterpillars in U.S. Soybean

Current Distribution and Population Persistence of Five Lepidopteran Pests in U.S. Soybean

Journal of Integrated Pest Management

Erin Hodgson, Ph.D., is a professor and extension entomologist at Iowa State University. Email: ewh@iastate.eduAnders Huseth, Ph.D., is an assistant professor and extension specialist at North Carolina State University. Email: ashuseth@ncsu.edu.

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