Pest Identification is Essential and Sometimes Surprising

Pest Identification is Essential and Sometimes Surprising

Throughout my 22 year history as an Extension Agent, I have been the first responder for all sorts of strange things farmers, ranchers, and landowners encounter.  This is one of the critical roles county agents play all over the country.  If you see something odd or unusual, whether it is a new weed, insect or disease, your county agent should be one of the first people you contact to get information.  It is very possible that if you find something you have never seen before, others may not have not seen it either.  County agents are connected to a vast network of experts and identification labs that can help figure out what those strange new things are. Because of the ports, huge numbers of visitors, and tropical storms, new pests and diseases show up in Florida on a regular basis.  It is very important to have new pests identified, before they have the opportunity to spread.

Most of the time the plants, bugs, and diseases agents have identified by experts are harmful in some way to the crops we grow.  Whether it is toxic weeds in pastures, insects feeding on plants, or diseases in crops, the first thing you need to know is, “What is it?” Once the issue is identified, most of the time there are some type of control options available.  Sometimes, however, things are not at all what you expect.  Such was the case this summer as four types of plant pests were identified that turned out to be harmless, and in some cases were actually beneficial.

Specimen #1

Aschersonia aleyrodis on Satsuma is a fungus that feeds on whitefly nymphs. Photo credit: Doug Mayo, UF/IFAS

A citrus grower thought that his satsuma trees were under serious attack.  White flies were already an issue as noted by the sooty mold growing on the leaves, and then this terrible scale that he had never seen was all over the undersides of the leaves of the trees.  While from a distance this looks much like a harmful scale insect, it turned out to be a beneficial fungus that destroys whitefly nymphs!

Dr. Xavier Martini, UF/IFAS Entomologist in Quincy shared the following information:

What you have is not scale, it is citrus whitefly nymphs that have been attacked by an entomopathogenic fungi called Aschersonia aleyrodis. It is very good to have this fungus, because it helps control the whitefly population.

You can read about this in the Featured Creature article entitled: Citrus WhiteflyScroll down to the section called: Parasitic fungi for more details.

Aschersonia aleyrodis fungus on the underside of a satsuma leaf looks terrible, but it was actually making a bad situation better by reducing the whitefly population on young satsuma trees. Photo credit: Doug Mayo, UF/IFAS.

Specimen #2

The beneficial fungus Beauveria bassiana is a natural enemy of kudzu bugs on soybeans. Photo credit: Doug Mayo, UF/IFAS.

A soybean grower saw something he had never noticed before.  A white mold was growing in spots all over the stems of soybean plants in a field.  This is where you have to be careful.  Soybeans can get white mold, which is caused by the fungus Sclerotinia sclerotiorum.  If you do a google search for Soybean white mold, you will find pictures that look somewhat similar.  Upon closer inspection, at the NFREC Plant Pathology Lab, in Quincy,  the fungus was actually Beauveria bassiana which is a biological control of kudzu bugs.  The white spots in the photos are actually dead or dying kudzu bugs, and the fungus was growing on the insects, not the soybean stalks.  You can read more about this beneficial fungus at: Kudzu bugs’ decline is attributed to two factors.

The white spots are beneficial fungus Beauveria bassiana that are attacking kudzu bugs not the soybean stalks. Photo credit: Doug Mayo, UF/IFAS

Specimen #3

Slime mold found growing on a centipede lawn. Photo credit: Doug Mayo, UF/IFAS

A landowner noticed this really strange growth on her centipede lawn.  It looks hideous and destructive.  In truth, it was a relatively harmless plasmodial slime mold, named Fuligo septica.

Larry Williams, UF/IFAS Okaloosa Horticulture Agent shared the following information:

Slime molds mostly function as saprophytes, feeding on and breaking down organic matter. It should not cause any permanent problems or major damage to the lawn. One such slime mold is commonly referred to as “dog vomit” slime mold.

Here is a link to an article on slime molds that pop up on lawns, in mulch, and damp areas under trees with high organic matter: Those Mysterious Molds

Slime mold growing on the moist organic matter in a Jackson County Lawn. Photo credit: Doug Mayo, UF/IFAS.

Oklahoma State University’s diagnostic labs had gotten so may calls from concerned homeowners that they developed a YouTube video on slime molds:

Specimen 4

Harmless slime mold growing on centipede lawn after multiple rainy days. Photo credit: Doug Mayo

A similar scenario was seen on a centipede lawn at a county building in Jackson County.  This slime mold is commonly found on lawns and pasture grasses during extended rainy periods in Florida. While it looks like a serious disease, it is really just another plasmodium species that feeds on decaying organic matter.  As with the large slime mold in specimen 3, what you are seeing is actually the spore masses that will generate more slime molds when conditions are favorable again for growth.  You can knock these off with a garden hose, if you want to, but they disappear almost as fast as they form.  No real harm is done to the grass that is just serving as a platform for slime mold reproduction.

Read more about it in this article written by Matt Orwatt, UF/IFAS Washington Horticulture Agent: Frequent Rains Induce Slime Mold in Panhandle Lawns

Summary

Most of the time, when you see something that does not look normal it is a bad thing, such as weeds, fungal diseases, or damaging insects. But before you spend money on a control, it is really important to have a positive identification of the pest.  Not everything unusual is harmful.  Modern pesticides have become very target specific, so it is vital to first find out what this new thing is before you spend money trying to control it.  So the next time you see something alarming or strange in your crop, pasture, or landscape, contact your local county agent, so you can find out for certain what you are dealing with, and get some science-based advice on a plan of action, if one is needed.

Atmospheric Temperature Inversions – Why Are They Important To Farmers?

Atmospheric Temperature Inversions – Why Are They Important To Farmers?

Temperature inversions form a kind of air layering or stratifying effect. It becomes visible when smoke or fog rises and then seems to abruptly hit an invisible ceiling. Credit Judy Biss

Farmers and ranchers must manage traditional business practices to be successful, but they also deal with the many challenges of ever changing weather.  Rain, wind, and temperature are important and obvious aspects of weather that producers track on a daily basis, but there are other, not so obvious weather features that affect operational management as well.  One of these is a phenomenon called “temperature inversions.

What is a Temperature Inversion?

Most of the time, if you were to take the air temperature at measured intervals starting from the ground, moving straight up in to the air, the temperature would be warmer at ground level than it is at higher levels over your head.   A temperature inversion is simply the reverse of this gradient – the temperature of air at ground level is cooler than the air above it.  These inversions occur naturally and most often in the late evening to early morning hours when there is little to no wind.  Temperature inversions form a kind of air layering or stratifying effect.  If you have ever seen smoke rise and then seemingly, and abruptly, hit an invisible ceiling, you have probably witnessed a temperature inversion.

Why are Temperature inversions important?

Temperature inversions are important because the air layering effect they cause changes the anticipated dissipation of pesticide spray solutions used by agricultural producers.  Inversions also affect the movement of smoke from prescribed fires used by land managers.  Under a temperature inversion, spray solutions and smoke have the potential to move great distances offsite instead of dissipating and diluting under normal atmospheric conditions.  To make a long story short, agricultural producers and land managers do not want their pesticide spray solutions or smoke to move offsite in such a way that could negatively affect non-targets areas.  Minimizing pesticide drift is a critical and routine part of pesticide application procedures.  There are a number of techniques pesticide applicators use to reduce pesticide drift.  One of these techniques is being aware of atmospheric temperature inversions.  This is especially important when using organo-auxin herbicides that have characteristics making them more volatile, and thus more affected by air currents.  Additionally, in light of the new herbicide application rules for dicamba resistant cotton and soybean varieties, managing pesticide drift is a critical part of stewardship of these new herbicides.

Detecting and Managing Temperature Inversions

Properly managing pesticide drift and smoke from prescribed fire includes using a number of best management practices by trained applicators and managers.  Being aware of temperature inversions is only one of the variables they incorporate into their management decisions every day.  Some herbicide labels have sections dedicated to explaining the importance of not spraying in areas where temperature inversions exist, and list ways to detect the presence of an inversion.  See for example, the herbicide  Engenia® by BASF This is one of the herbicides approved for use on the new dicamba resistant cotton and soybean varieties.  Before herbicides approved for use on these new plant varieties can be used, the pesticide applicator must attend a specialized training on proper stewardship of these products.

The Engenia® Herbicide Resource Center provides a number of Technical Information Bulletins, one of which details Recognizing Temperature Inversions. Below is an excerpt from that bulletin.

How to Identify if an Inversion Exists:

  • Measure air temperature at 6–12 inches above the soil and at 8–10 feet above the soil. An inversion exists if measured air temperature at 8–10 feet above the soil is higher than the measured air temperature at 6–12 inches above the soil. Be sure the instrument is shaded and not influenced by solar heating.
  • Morning dew
  • Morning fog (indicates that an inversion existed prior to fog formation)
  • Smoke or dust hanging in the air or moving laterally
  • Overnight cloud cover is 25% or less
  • Inversions can begin forming three to four hours before sunset and can persist until one to two hours after sunrise

This 3 minute video from the University of Minnesota Extension, provides great information on temperature inversions and how to detect them.

 

For additional resources on the topic of Temperature Inversions and Pesticide Drift Management, please see the following publications:

 

 

Still Need the Mandatory Dicamba Resistant Crop Training?

Still Need the Mandatory Dicamba Resistant Crop Training?

Last year, the Environmental Protection Agency (EPA) registered new dicamba herbicide product formulations for making applications to dicamba tolerant cotton and soybean crops. As a result, many states were overwhelmed with drift complaints regarding sensitive crops. This led to the 2018 EPA announcement requiring that anyone who wishes to apply dicamba to dicamba tolerant crops MUST participate in an auxin herbicide training before making applications in 2018.

[warning]This training is required of anyone applying newer dicamba products registered for use on dicamba tolerant cotton and soybeans.[/warning]

Product examples include XtendiMax, Engenia, and FeXapan. Applicators using older dicamba formulations in other crops (corn, forages, small grains, sorghum, and turf) can still apply dicamba products without having this training but thoseproducts CANNOT be used on the dicamba tolerant crops. If you have questions regarding the use of these products or if you need the training, call your local Extension Office before making any applications.

On March 16, Extension Offices from across the state hosted an online two-hour dicamba training, which was broadcasted live from Gainesville. This training was overseen by the Florida Department of Agriculture and Consumer Services (FDACS), who determined that the CEU form received from completion of this training would serve as the official documentation of attendance. If applicators desire to use the form for CEUs towards renewal of their pesticide license, they are required to keep an additional copy in their possession as proof of completing the dicamba training.

The training was recorded live and made available to all participating Extension Offices (see below). If you plan to make dicamba applications to dicamba tolerant cotton or soybean, you MUST complete this training before making any applications. The training is not required before planting dicamba genetics, but without the training dicamba cannot be sprayed on the crop. If you plan to spray the crop with dicamba, or want the weed control option later in the season, the training is mandatory.

[important]The recorded training has been made available to all participating Extension Offices. Applicators are required to watch it at the Extension Office, where it can be proctored by an agent who is a certified CEU provider and can issue/sign the CEU form. There are no exceptions, you must watch the training at an Extension Office. In the Panhandle, participating Extension Offices with access to the training include: Calhoun, Escambia, Gadsden, Holmes, Jefferson, Okaloosa, Santa Rosa, Walton, and Washington Counties. Contact information for the different offices can be found using the following link: Florida County Extension Offices.[/important]

 

Permit Required for AgLogic Nematicide Use in Cotton and Peanuts

Permit Required for AgLogic Nematicide Use in Cotton and Peanuts

Ethan Carter, Regional Crop IPM Agent, and Zane Grabau, UF/IFAS Nematologist

Newly registered for Florida, AgLogic 15GG (gypsum formulation) is a granular nematicide available for use in Florida cotton and peanut. The active ingredient in this product is aldicarb, which you may remember was the active ingredient in Temik.

[warning]Producers who plan to utilize this product for the upcoming 2018 crop season are REQUIRED to obtain an aldicarb permit through FDACS PRIOR to any applications being made. A separate permit application is required for each field where aldicarb will be applied.[/warning]

The one page permit application for applying aldicarb in Florida can be downloaded here. Once filled out, the permit application needs to be submitted to Tamara James, FDACS by email or fax (850) 617-7895. The website for submitting applications on the existing Temik page is currently being updated, and will be functioning in the near future.

Aside from the aldicarb permit, producers will also need to be in possession of a restricted use pesticide license, and strictly follow the label instructions for this product. See label for mandatory minimum distances between the nearest well and aldicarb application, as these distances vary based on soil type and well casing.

[important]Grazing restrictions are also associated with this product.  Peanut hay and vines cannot be fed to livestock following AgLogic application. [/important]

This granular product should be applied in-furrow at planting, and may be followed by a post-emergence application before peanut pegging or cotton squaring. The post-emergence application must be side-dressed in an open furrow, and immediately covered with soil. Maximum application rates are 7 lbs./acre at planting for both crops, 5 lbs./acre post-emergence for cotton, and 10 lbs./acre post-emergence for peanut.

Aldicarb Permit Application

Submission contact – Tamara James (email) or fax (850) 617-7895

 

Why is Nematode Damage Patchy in Crop Fields? How Does this Affect Management Decisions?

Why is Nematode Damage Patchy in Crop Fields? How Does this Affect Management Decisions?

I’ve had the opportunity to visit a number of grower fields this summer to assess potential nematode damage and I’ve often been asked this question: “Why is nematode damage worse in one section of a field than another, or worse in one field than another one nearby? ” This question reflects the fact that nematode population densities and damage are often patchy both within a field and between different fields.

Patchy necrosis (dead or dying plants) and chlorosis (yellowing) in a peanut field with severe root-knot nematode infestation.

There are a number of reasons nematode infestations or damage is often patchy:

  1. Management history

This is an important factor for variation between fields.  Factors such as crop rotation, cover crop use, weed management, nematicide use, use of resistant cultivars, and other practices all affect nematode populations.  Nematodes need a living host crop to feed on and reproduce, so nematode populations will be higher in areas where a host cash crop, cover crop, or weed has grown.

  1. Nematode dispersal is (usually) relatively slow

Nematodes don’t move far on their own.  Rather, they are moved by human or natural activity, often slowly. Nematodes are moved to new fields or moved within a field on farm equipment, infected plant material, or water or wind-born soil.  Therefore, a new nematode infection in a field often starts from a single point, such as near a field entrance, and spreads relatively slowly.

  1. Field variation in soil type and other properties or features

Soil properties such as soil type, temperature, and moisture can affect nematode reproduction, and when these factors vary within or between fields, nematode population densities do as well.  Most nematodes prefer sandy soil, and are more likely to thrive in sandy fields or sandy patches within a field.  One exception is reniform nematode which tends to do best with moderate amounts of sand (70-80%) and is a pathogen of cotton, soybean, and most vegetables.  Nematodes prefer a moderate amount of moisture and relatively high temperatures, so if these factors vary across a field, perhaps due to hills and valleys, nematode populations may vary as well.

  1. Field variation in crop health, weeds, pathogens, biocontrol organisms, and other biological factors

Crop health can also affect the severity of nematode damage, as a healthy plant can better withstand nematode infection than a plant stressed by nutrient deficiency, drought, competition from weeds, or other factors that can vary across a field.  Similarly, crop damage is often increased when soil-borne pathogens and nematodes co-infect.  A number of soil-borne bacteria and fungi are known to kill nematodes and could act as natural biocontrol agents, helping keep nematode populations low.  Variation in populations of pathogens and biocontrol agents across fields may contribute to nematode damage or population variation.

Patchy chlorosis (yellowing) in a peanut field due to root-knot nematode.

Knowledge of population density should influence nematode management practices in a number of ways:

  1. Work to control the spread of nematodes

Because human activity is one of the main ways nematodes are moved, human actions can help slow nematode spread, especially from field to field.  Use nematode-free planting material, don’t move plant material from field to field, and wash equipment free of soil when possible.

  1. Account for field variation when sampling for nematodes

Sampling for nematodes is an important part of a nematode management strategy.  When sampling for nematodes, sample areas at high risk of nematode damage (sandy, poor fertility) separately from areas at lower risk of damage.  This could coincide with soil mapping, such as with a Veris rig or soil type maps, and division into management zones.

  1. Spot-treat areas with nematode problems

Once a field is infected, nematode management relies on crop rotation, resistant cultivars, and nematicide application.  Particularly for expensive, high-input nematode management practices such as nematicide application, treating only the areas of a field with nematode problems can save time and money.  Ideally, areas with nematode problems should be identified by sampling and could coincide with management zones based on soil properties.

  1. Promote crop health and manage weeds

Soil type and other factors that affect nematode distribution are hard to control, but growers have some control over crop health and weeds.  A healthy crop is more tolerant of nematodes, so properly fertilized crops and the use of other practices to promote vigor can reduce yield losses.  As discussed above, weeds also harbor nematodes, so it is important to manage weeds early.

Further information and resources can be found in the following UF/IFAS EDIS fact sheets:

Sampling for nematodes

Florida cotton nematode management guide

Nematode management in tomatoes, peppers, and eggplant

Precision agriculture

 

Scout Soybeans for Kudzu Bugs and Redbanded Stink Bugs

Scout Soybeans for Kudzu Bugs and Redbanded Stink Bugs

Soybean sentinel plot in Marianna- Jackson County, Florida. Photo by Ethan Carter.

After a mild winter, with relatively few nights below freezing, it should be no surprise that insect populations are spiking early. One example of this is armyworms, which began showing up in early-mid June across areas of Jackson County, a pest typically found later in July.  In early June, soybean pests have begun to appear in the sentinel plot at the Jackson County Extension Office. The plot was checked for pests at the Scout School on June 8, and aside from beneficial insects, only several brown stink bugs were found.

Kuzu Bugs

By the second week of June (June 13),  kudzu bugs had moved in and were found in high numbers along plot edges.

Six kudzu bugs feeding on a soybean plant. Photo by Ethan Carter.

This follows a similar trend, with kudzu bugs returning in higher numbers this year as compared to the last few. Kudzu bugs feed on sap from the plant’s main stem and leaf petioles using their sucking mouth-parts. The complete life cycle from egg to adult can be achieved in as little as six weeks. The past few years, a beneficial fungus (Beauveria bassiana) helped reduce kudzu bug numbers, hopefully that will happen again this year as well.

Scouting fields will allow you to stay current on the population distribution and determine economic thresholds. When scouting, avoid sampling near border/edge rows which tend to be colonized first. Insecticide applications should only be made when populations reach the necessary threshold levels –  1 nymph per sweep. This may be several weeks from the point of initial infestation. Pyrethroids containing bifenthrin work well against these insects.

Redbanded Stinkbug

Another recent pest to show up in the soybean plot at the county Extension office is the redbanded stink bug.

Adult redbanded stink bug in soybean. Photo by Ethan Carter.

The redbanded stink bug is a key soybean pest in states such as Louisiana and Arkansas, and could be a problem for Florida if it continues to show up in soybean fields. Like other stink bugs, the redbanded uses piercing sucking mouth parts to feed on plant stems, leaves, and pods. That being said, the redbanded stink bug does more damage per individual than any other stink bug species. Growers find they can control southern green and green stink bugs easily enough while the brown stink bugs pose more of a problem, but the redbanded is harder still. There is also a redshouldered stink bug (not a pest) that is similar in appearance to the redbanded, but differs in that the redbanded has an abdominal spine.

Adult redshouldered stink bug. Photo from Bugwood Images.

The redbanded stink bug also typically has two small black spots on its dorsal (back) side (see image below), whereas the redshouldered stink bug does not.

Adult redbanded stink bugs- left side showing two black spots on the dorsal side, right side shows abdominal spine located near where the (removed) legs would join. Photo by Ethan Carter.

The threshold level for redbanded stink bugs used in Alabama for soybeans is 1 per 3ft of row, or 2 per 15 sweeps. While products containing bifenthrin can control brown stink bugs, for the redbanded it is recommended to use the maximum combined rates of bifenthrin and acephate.

For more information or assistance with insect identification, contact your local Extension Office.  For control options use the following publication link:

Alabama Soybean Insect, Disease, Nematode, and Weed Control Recommendations for 2017