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.

New North Carolina Tomato Varieties Offer Disease Resistance and Better Flavor

New North Carolina Tomato Varieties Offer Disease Resistance and Better Flavor

Dr. Randy Gardner discussing NC State tomato varsity trials. Photo Credit: Matt Lollar

A few weeks ago I was lucky enough to attend North Carolina State’s Tomato Field Day, at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC.  Every summer crowds flock from all over the Southeast to learn what’s new in the world of tomatoes.  Since it’s not always convenient for you to drop what you’re doing to make a road trip to North Carolina, I’ll highlight something I learned from the field day.

New Varieties with Dr. Randy Gardner and Dr. Dilip Panthee

Dr. Randy Gardner is a retired tomato breeder from NC State with more than 30 years of experience.  Dr. Dilip Panthee is NC State’s newest tomato breeder.  Both are working on developing new cultivars with both disease resistance and an added emphasis on flavor.  The three main diseases they are focusing on for resistance and/or tolerance are Late Blight, Bacterial Spot, and Verticillium Wilt Race 2.  See the list below of some of their newest releases.  Just remember that these varieties were developed for North Carolina growing conditions, so it’s recommended that you give them a try on a small scale to evaluate them for your area.The varieties listed in the table above are available in the market.  For a sneak peak of what’s in store for the future, check out this poster developed by Dr. Panthee:  NC State Tomato Variety Replicated Trials 2018.  More details on NC State’s tomato research can be found at the Mountain Horticultural Crops Research and Extension Center website.  Thanks to NC State for an excellent field day!

Dr. Randy Gardner and Dr. Dilip Panthee, NC State tomato breeders, are working on disease resistance with an added emphasis on flavor. Photo credit: Dr. Dilip Panthee, NC State

 

Heaves – The Horse Version of COPD

Heaves – The Horse Version of COPD

Heaves is a non-infectious respiratory disease of horses that is similar to Chronic Obstructive Pulmonary Disease (COPD) in humans. It is considered progressive, and degenerative. That means it will never go away completely and each bout will get progressively worse.

There are a number of forms relative to cause, but they share similar symptoms. Horses react to an allergen and airways become restricted so air cannot move normally. The tissues of the lungs become inflamed and thicken. An affected horse will likely cough, wheeze, have an increased respiration rate, flared nostrils, nasal discharge and will become intolerant to exercise.  Removal of the irritant often abates the symptoms, so remission can occur. With each successive bout however, the lungs lose more elasticity. Over time, breathing out requires as much energy as breathing in. The result is enlarged abdominal muscles in the area of the flank that are referred to as “heave lines.” Figure 1.

Figure 1. Enlarged abdominal muscles in the area of the flank that are referred to as “heave lines.” Source: Twin Pines veterinary Services.

Though there is no cure, the symptoms can be treated orally or with injections. Corticosteroids can help reduce inflammation. Unfortunately, laminitis and/or generalized infection can occur with prolonged use of corticosteroids. Aerosolized bronchodilators (Ventolin/Proventil or albuterol) can be prescribed and administered with a tight fitting mask placed over the horse’s nose that works much like an inhaler for humans. Figure 2.  Though costly, they are very effective and have fewer side effects.

Figure 2.  Aerosolized bronchodilators that work much like an inhaler in humans can be prescribed and administered with a tight fitting mask placed over the horse’s nose. Source: Twin Pines Veterinary Services.

You can manage the disease by minimizing exposure to allergens. Keep records of occurrence so that you can identify the triggers and when they occur. Determine if it is seasonal or year round. To stop the irritation, change the environment, reduce dust, soak hay. If your horse has seasonal heaves, it is likely due to an irritant associated with grazing pasture. You can place the affected horse in dry lot during seasons when they are reactive to pasture.

Though the precise allergen(s) in grasses have not be defined in Florida, there is reason to suspect endophytes and mycotoxins as triggers. In an effort to identify grass species that contain fungal endophyte and mycotoxin presence, UF/IFAS researchers, led by Ann Blount, UF Forage Breeder, have received funding from the Florida Cattle Enhancement Fund. Researchers are currently sampling bahiagrass, bermudagrass and limpograss pastures on approximately 13 ranches state-wide over a period of one year. Analysis of these samples will help UF/IFAS researchers provide unbiased information about endophyte and mycotoxin presence in forages and how it relates, if found, to animal health and performance.

If you think your horse is suffering from heaves, contact your veterinarian for diagnosis and a course of treatment.

 

Peanut Fungicide Spray Strategies: The Values of Alternating or Mixing Modes of Action

Peanut Fungicide Spray Strategies: The Values of Alternating or Mixing Modes of Action

 

By Nicholas Dufault and Wael Elwakil

Fungicide resistance or reduced efficacy is a concern when managing peanut diseases, especially the foliar diseases early and late leaf spot. Managing these concerns requires an integrated approach with constant monitoring of the product’s efficacy and application programs to avoid resistance selection. Two common resistance management strategies are alternating (or rotating) and mixing fungicide product modes of action (MOA). It has been indicated that MOA mixtures are a more sustainable strategy for resistance management than alternating, but they may be costlier as they tend to increase the spray program’s number of fungicides. So, it is important to understand the value of these two strategies especially when using products that have a moderate to high risk for resistance selection.

A recent study explored the value of these strategies using the fungicide products azoxystrobin (Abound 2.08), pyraclostrobin (Headline 250 SC) and tebuconazole (TebuStar 3.6L). All these products are off patent and considered medium to high risk for leaf spot resistance or reduced sensitivity. The study consisted of various spray programs that had five applications of chlorothalonil (Chloronil 720) at 30, 44, 72, 100 and 114 days after planting (DAP). The at-risk products were then applied at approximately 58 and 86 DAP either alone (alternation program) or in combination with chlorothalonil (mixture program). The study was conducted at two locations in Marianna and Citra, FL during the 2017 season. The mixture programs generally had higher yields than the alternation programs (4 times out of 6), however, only one of these yields was significantly different (Fig 1). Both strategies provide significant yield savings compared to the untreated control plots (data not shown).

Yield Results

Figure 1. Yield results from the various fungicide alternation and mixture programs at the two locations. Fungicide products consisted of azoxystrobin, pyraclostrobin, tebuconazole and chlorothalonil. All programs consisted of 5 applications of chlorothalonil with the products indicated on the x-axis applied alone or in combination with chlorothalonil at 58 and 56 days after planting. The yield was significantly greater for the mixture program compared to the alternation in the pyraclostrobin treatments for the Marianna location.

Identifying the pathogen population present is a key component when assessing these two strategies. Location populations varied with late leaf spot being the primary pathogen in Marianna, and early leaf spot in Citra (Fig. 2). It is also important to note that significant pressure was also present from late leaf spot and rust in Citra as well. This variation in pathogen population could be one possible reason for the inconsistencies observed between these strategies at each location. It does seem apparent that in situations where multiple pathogens are present that alternations are not as effective as mixtures.

Figure 2. Disease incidence percentages in the untreated control treatments for Citra and Marianna, FL. Early leaf spot, late leaf spot, and rust were rated separately on leaflet samples (48 leaflets/treatment). Disease incidence shown represents average seasonal incidence recorded in the locations during 2017.

Mixing fungicide MOA appears to be the optimal strategy for disease control, yield savings and managing fungicide resistance. However, alternating MOA is also a successful strategy, but its efficacy appears to be highly dependent on the pathogen populations present. Regardless of the strategy chosen, disease control and yield savings were improved with these strategies compared to the untreated plots. Both strategies will help sustain the efficacy of a fungicide product, and if cost is an issue then alternating modes of action in a program is better than repeated applications of a product alone. It should be noted that when using generic products like these, the average cost only varied by approximately $2.50 per acre. The cost of mixtures will depend largely on the mixing partners used, and with some planning these costs can be minimized.

Fungicide resistance management should be an important component of any peanut disease management program. More information about fungicide resistance and its management can be found in this UF/IFAS publication, Fungicide Resistance Action Committee’s (FRAC) Classification Scheme of Fungicides According to Mode of Action, or by contacting your local extension office.

 

Double Cropping Options for a Fall Vegetable Crop

Double Cropping Options for a Fall Vegetable Crop

Fruit and vegetable production on plastic mulch is a substantial investment.  To help justify the high input cost, farmers oftentimes choose to double crop.  This practice can provide a significant amount of additional income for the farm if a good farm management plan is in place, there is a demand for the product, and the weather cooperates.

plastic mulch bed

Plastic mulch beds. Photo Credit: Blake Thaxton.

Field Prep

Spring fruit and vegetable crops are usually grown on black plastic mulch, but fall crops are usually grown on white plastic.  Black plastic mulch helps absorb heat to warm the soil in the late winter and spring.  White plastic mulch helps reflect light to cool the soil in the late summer and fall.  In order to reuse black plastic from the spring, painting the mulch is recommended.  White interior latex paint can be diluted with water and sprayed on the plastic.  At least one study has shown the ratio of paint to water can vary drastically without any significant difference in yield.

Crop residue leftover from the spring crop should be removed to reduce the risk of plant and human pathogens and deter harboring of insect and rodent pests.  If pests are an issue or a potential threat, then the soil can be fumigated before the second crop is planted.  Also, it is important to continue to irrigate the beds during the time between the two crops.  This will ensure a good water distribution throughout the bed when the second crop is planted.

Fertilization

When double cropping, it is important to consider each crop’s fertilizer needs independently.  Never assume that excess fertilizer from the spring crop will be taken up by the fall crop.  Take a soil sample before the second crop is planted to determine nutrient deficiencies.  If phosphorus is required for the second crop, then phosphoric acid can be injected through the drip.

Stringing tomatoes. Photo Credit: UF/IFAS Photo by Tyler Jones UF/IFAS Communication Services

Crop Selection

It is never a good idea to plant members of the same plant family sequentially, such as tomatoes after an eggplant crop, or zucchini after a watermelon crop.  The Vegetable Production Handbook of Florida lists production practices for various crops by plant family.  Recommended fall crops to follow tomatoes include: squash; broccoli; or cabbage.  Recommended fall crops to follow watermelons and other cucurbits include: peppers; tomatoes; or broccoli.  Consider plant spacing when selecting a second crop.  Added holes in the plastic mulch will reduce it’s integrity and promote weed growth.  No matter what crop you choose to plant this fall, make sure you have a good marketing plan in place, with your buyers already lined up.

 

Equine Infectious Anemia is Still a Concern for Horse Owners

Equine Infectious Anemia is Still a Concern for Horse Owners

Horses at the University of Florida Horse Teaching Unit. UF/IFAS Photo by Tyler Jones.

Sometimes we can get complacent and forget why we do things. A Coggins test in horses is one of those things.  We know that it is a requirement in Florida to have a current negative Coggins test (within the last 12 months) in order to:

  • Move horses within the state,
  • Move horses out of the state,
  • Change ownership of the horse,
  • Breed horses,
  • Congregate horses for the purpose of shows, exhibits, sales/auctions, trail rides, rodeos and even boarding.

Normally, proof of negative Coggins test is in the form of a paper with information about the owner, horse and lab performing the test. Cards (negative EIA test verification cards) are available for an additional fee.  These cards are more convenient for those who travel often with their horses.

But why do we need a negative Coggins test every 12 months?

The Coggins test screens horses for Equine Infectious Anemia (EIA), a viral disease that has no vaccine and no treatment. A veterinarian must collect the blood sample and send it to a state and federally approved lab for testing.  The US started using this test in 1972 and has significantly reduced the number of new cases since then.  The EIA virus is transmitted by large biting flies such as horseflies and deerflies.  Contaminated needles and equipment can also spread this virus.  Horses with EIA can show clinical signs such as fever, weight loss, yellowing of skin, anemia, swelling of limbs and weakness.  Some horses with EIA show no signs of infection, but can still transmit the virus to healthy horses.

Horses that test positive for EIA are either euthanized or segregated from negative horses. USDA has set forth Uniform Methods and Rules for detecting, controlling and preventing the spread of EIA in the US. This is the minimum standard for states to follow.  Florida rules exceed these minimum standards since we are an historic “hot zone” state.

In 2017, 108,388 Coggins tests were performed in Florida with 2 horses testing positive. So far in 2018, one positive horse has been reported in March in Hardee County. Currently in the US less than 0.01% of horses tested are positive for EIA.  In 1972, when testing was implemented 4% of horses tested were positive.  If we get complacent and ignore EIA, since it is no longer very prevalent, we will see an increase in cases around the US.  Since there is no vaccine and no treatment for this disease, which can be fatal, testing is our best defense against this virus.