Category Archives: Pest Group

Section 18 Emergency Exemption approved for Virginia cotton

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Virginia cotton growers can now use Transform to control tarnished plant bug in cotton in 2019 (June 1 – Oct 1). This product will allow us to rotate modes of action and reduce our dependence on acephate and pyrethroids to manage this potentially destructive pest. Transform is softer on beneficials too, but you must notify beekeepers within 1 mile of cotton fields and, if there are known hives, apply before 7am or after 7pm when cotton is flowering. Transform is applied at 1.5-2.25 oz/A. Follow all label directions and keep a copy of the label with you when applying.

19VA02_Transform_WG_Label_Cotton

Based on early sampling numbers, we will have another high pressure year. Spray test results from the Tidewater AREC (shown below) can help you chose insecticides. Neonicotinoids (Admire, Belay, Centric, Endigo) should not be used after first bloom and are less effective during this time. Diamond is a growth regulator and is more effective against nymphs. There is evidence that it suppresses adult reproduction.

The single most important thing you can do to protect cotton from plant bugs is to spray at extension recommended thresholds (8 per 100 sweeps or 2-3 per drop cloth sample). As always, the only way to know what is in your field is to scout.

Call/text/email me if you have questions.

Thrips dispersal and foliar sprays

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Virginia cotton requires a thrips control product at planting to preserve yield and avoid maturity delays. This is especially true since the arrival of tarnished plant bugs. Any maturity delay early-season will likely magnify plant bug injury. Cotton planted at the end of April and first week of May has put on 1-2 true leaves. It is time to scout for thrips injury and make foliar applications when necessary.

Levels of injury to cotton seedlings rated from ‘0’ (no damage) to ‘5’ (dead terminal
or plant) from thrips. Injury at ‘2-3’ or above approximates a threshold for intervention with an
insecticide application. (Photo and caption from Kerns et al., 2018)

Using a seed treatment alone will likely require a foliar spray based on research from the Tidewater AREC. In-furrow aldicarb and in-furrow imidacloprid with a seed treatment should not need a foliar spray. Scout cotton planted with in-furrow imidacloprid alone and determine if a foliar application is necessary (often it is not – saving you time and money).

All cotton planted in Virginia is under high risk for thrips injury. NCSU prediction model shows risk increasing in later-planted cotton. This model was highly accurate in 2018.

Tips for foliar applications: Consider plant-date and growing conditions. Cotton planted late-May into warm soil may not need a foliar spray. Do not apply foliar acephate if plants are growing fast with no to minimal thrips injury. Thrips injury is likely for all cotton planted in Virginia and risk will be high until plants are no longer susceptible. The three diagrams below from the NCSU model show when seedling susceptibility declines based on planting date (May 1, May 8, May 15). The blue line on these diagrams shows you when risk for thrips injury is highest.

Spraying is most effective when the first leaf is the size of a pencil tip to a mouse ear. I recommend a 6-8 oz. rate of acephate. Several scenarios may be responsible for reduced efficacy of sprays:

1. Rain. Acephate is not a rain fast product. Consider reapplying if necessary.

2. Resistance. Acephate at 3 oz. per acre has become less effective in spray tests. Rotate to Radiant if another spray is required or use a higher rate.

3. Species composition. Tobacco thrips are most common in VA, but western flower thrips can co-infest. Acephate is less effective on this species. Rotate to Radiant if another spray is required.

As always, call/text/email me with any questions. Good luck and happy planting!

Wheat Disease Update – May 9, 2019

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Fusarium head blight (FHB) risk is continuing to increase in parts of Virginia. Upcoming rain events will increase risk over the next three days (see figure below). Much of the wheat in the southern part of the state is past the vulnerable flowering stage, but wheat that is at or about to enter flowering may be at risk. Consider applying a fungicide if risk is moderate to high, especially on susceptible or moderately susceptible varieties. Fungicides should be applied at early flowering or up to one week later. Do not apply a strobilurin-containing fungicide since this can increase DON contamination. Recommended fungicides include Prosaro, Caramba, Proline, and Miravis Ace. Increased incidence and severity of leaf blotch and powdery mildew have been observed in some fields, and these fungicides will also provide control of foliar diseases.

Wheat Disease Update – May 1, 2019

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There is increased risk of Fusarium head blight (FHB) in some parts of Virginia, especially near the Northern Neck and Eastern Shore of Virginia. Wheat in much of the state is flowering, and if a field is in a high risk area a fungicide application is recommended. Recommended fungicides for control of FHB and DON contamination include Caramba, Prosaro, Proline, and Miravis Ace. Do not apply a strobilurin-containing fungicide after the flag leaf stage since this has the potential to increase DON concentrations in the grain. To maximize their effectiveness, fungicides for FHB and DON control should be applied at early flowering or up to one week later. Fungicides that control FHB and DON will also control foliar diseases including powdery mildew, leaf rust, stripe rust, and leaf blotch.

Wheat varieties vary in susceptibility to FHB and DON, and this should be considered when making decisions of whether or not to apply a fungicide at flowering for FHB control. The FHB Risk Tool (http://www.wheatscab.psu.edu/) allows you to select the susceptibility of your wheat variety to determine risk. You can find information on FHB susceptibility of your wheat variety from your seed dealer or in the Virginia Cooperative Extension Small Grains publication. The FHB Risk algorithm adjusts the relative risk based on the variety susceptibility as illustrated below. For assistance with small grains disease identification or for additional management recommendations contact Dr. Hillary Mehl, Extension Plant Pathologist (hlmehl@vt.edu).

FHB risk for susceptible (S) wheat, May 1, 2019.

FHB risk for moderately resistant (MR) wheat, May 1, 2019.

Wheat Disease Update – April 25, 2019

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Most of the wheat crop in Virginia is currently between flag leaf emergence and heading with some wheat close to the flowering stage. Foliar diseases including powdery mildew and leaf blotch have been observed in some fields, but overall levels of disease have been low so far. As wheat reaches the flowering stage, it is susceptible to infection with Fusarium head blight (FHB), and this is the critical stage for making fungicide applications. Currently, the risk for FHB infection is low throughout Virginia. In addition, the 3-day forecast indicates risk will remain low. FHB risk can be monitored using the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/).
Recommended fungicides for control of FHB and DON contamination include Caramba, Prosaro, Proline, and Miravis Ace. Do not apply a strobilurin-containing fungicide after the flag leaf stage since this has the potential to increase DON concentrations in the grain. To maximize their effectiveness, fungicides for FHB and DON control should be applied at early flowering or up to one week later. Fungicides that control FHB and DON will also control foliar diseases including powdery mildew, leaf rust, stripe rust, and leaf blotch. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu). The 2019 Fungicide Efficacy Table for Wheat can be downloaded below.

NCERA 184 Wheat fungicide table 2019_Final

Aphids in alfalfa

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Large aphids populations have been observed in alfalfa this year following insecticide applications targeting alfalfa weevil. If you haven’t scouted for alfalfa weevil in Virginia, you should. See the bottom of this post for a weevil summary.

Aphids, typically pea aphids, can be problematic when their natural enemies are disturbed. They can reduce vigor and cause wilting in first cuttings. If early cutting is not an option, several insecticides (mostly pyrethroids) are labeled for their control. Low label rates are generally effective as long as you ensure good coverage. Scout for aphids by pulling 30 random stems per field and counting the number of aphids. This guide from Iowa State can help you make treatment decisions.

Most of the aphids I have seen in Virginia alfalfa are pea aphids (left) and cowpea (right). If you think you have another species, please give me a call or send an email.

Photos Erin Hodgson, Iowa State

My thanks to Lane Grow from Southern State Cooperative for his ongoing efforts to scout and report problems in western Virginia.

Alfalfa weevil information

Scout fields by pulling 30 random stems and inspecting foliage for weevils. Weevil larvae are small, can be white, yellow, or green, and have black heads. They are often tucked tight into new growth. It’s possible to dislodge larger larvae so be careful or collect stems into some container that catches these. I use a plastic freezer bag and insect stems in the shop or truck. This guide from Penn State can help you make spray decisions. Cutting alfalfa is an option if you don’t want to use pesticides. I recommend using clorpyrifos based on spray tests in 2018 and 2019. Some people have been successful with indoxacarb (Steward) or pyrethroids (many brand-name and generic options). Coverage is essential with any product.

 

Herbicide Resistant Weeds Workshops Slated for Maryland, Virginia, and Delaware

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A series of half-day workshops will be held in Maryland, Delaware and Virginia this winter for farmers interested in learning about the problems of herbicide resistant weeds and how to manage them. Hosted by University of Maryland Extension in collaboration with Virginia Tech and University of Delaware, these workshops are designed to equip farmers with the knowledge to improve weed control on their farms.

Farmers in the mid-Atlantic area are starting to see the impact of herbicide resistant weeds on their crop yields. With many problematic weeds now found throughout the region it is essential that farmers learn the key management strategies to control these weeds.

Sessions will cover integrated weed management tactics; palmer amaranth, common ragweed and marestail control strategies; and developing a weed management plan. There is no charge to attend and lunch will be provided. Pesticide (commercial and private) and CCA continuing education credits will be offered.

Workshop locations and times are listed below. Please RSVP to the respective meeting location to provide an accurate meal count.

February 25th (12 pm to 5 pm) Old Beale Sanctuary, 369 Queen Street,Tappahannock, VA 22560

To register call the Essex County Extension Office: at (804) 443-3551

February 26th (8 am to 1 pm) St. Mary’s County UME Office, 26737 Radio Station Way, Leonardtown, MD 20650. To register call the St. Mary’s County UME Office at 301-475- 4484

March 4th (8 am to 1 pm) Harrington Volunteer Fire Company, 20 Clark St, Harrington, DE 19952. To register call the UD Carvel REC, at 302-856-2585 (ext 540)

March 5th (8 am to 1 pm) Somerset Extension Office, 30730 Park Drive, Princess Anne, MD 21853. To register call the Somerset County Extension Office at 410- 651-1350

March 6th (8  am to 1 pm) Frederick County UME Office, 330 Montevue Lane, Frederick, MD 20712. To register, call the Frederick County UME Office at 301-600- 3576

March 7th (8 am to 1 pm) Chestertown Volunteer Fire Company, 211 Maple Ave, Chestertown, MD 21620. To register call the Kent County UME Office at 410-778- 1661

For more information contact Ben Beale at 301-475-4481, Michael Flessner at 540-315-2954, Matt Morris at 301-600-3578 or Mark VanGessel at 302-856-7303.

Dicamba Training Opportunities

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If you intend to apply Engenia, Xtendimax, or FeXapan this year, you need to complete the annual dicamba specific training requirement in addition to being a certified pesticide applicator. In Virginia, this training is conducted by the registrants (manufacturers), but can also be completed in another state including registrant training, state mandated training, and state approved training. Both in person and online training is acceptable. Training is not product specific; you do not have to take the training from the registrant of the product you apply.

Make sure to document your training.

Here are links to find a training event near you or complete online:
BASF

Bayer

Corteva

University of Nebraska

Please note that some some events require pre-registration.

The following links are under revision for 2019 but will be useful shortly:
Mississippi State Extension

Early Harvest Reports – Soybean Seed Quality is Not Good

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David Holshouser, Soybean Agronomist & Hillary Mehl, Plant Pathologist

We appreciated the rainfall this year.  It should lead to some very good yields in many parts of Virginia.  However, the same weather conditions for high yields has led to some of the worst seed quality that we’ve ever experienced.  This is in addition to the pod splitting and seed sprouting that we began observing last month.

We began seeing extremely poor seed quality in our May-planter maturity group (MG) 3 soybean in our Orange variety test last week.  The early MG 4 soybean did not look much better, but they were not yet mature.

The photo on the left is the worst that has been called to my attention.  These are April–planted early MG 3 soybean from Madison County.  To use the farmer’s words, “A real kick in the stomach.”  Soybean in this shape are pretty much a total loss.  It is especially hard when the yield potential was outstanding.

Below are photos from Westmoreland and Dinwiddie counties showing similar results.  We are not seeing the same problems in our May-planted MG 4 soybean in Suffolk, but are seeing quite a bit of purple seed stain in some varieties.

So, what caused this?  From these photos, we are seeing signs of several diseases, including Phomosis/Diaporthe, Cercospora, and anthracnose just to name a few.  However, we have not yet confirmed the diseases – samples are on the way to the Tidewater AREC’s disease lab.

But that is just the possible diseases.  What caused the disease to be so bad?

I think that we can blame it largely on excessive rainfall (and many rainfall events) and a very warm September.  Most of the seed diseases come on strong during maturation; hence, our early MG soybean, especially those planted in April and early-May experienced those conditions.

Below is a weather summary from the month of September in Orange County, showing 2018 and long term average temperatures and accumulated precipitation.  Notice the high rainfall, especially during the latter part of the Month, when our MG 3 and early-4 soybean were maturing.  Secondly, notice the temperatures during that same time period.  This set up nearly perfect conditions for many seed diseases to form.

  

What can we do about it?  Unfortunately, we cannot control the weather.  And what we have done this year cannot be undone.  But, here are a few pointers for that may help this and in future years.

  • Harvest as soon as possible after soybean are mature. The diseases will only continue to grow and develop.  If you have drying capability, harvest at a little higher moisture and dry it down to 13%.
  • Plant varieties best adapted to your farm(s). While you have discovered (and heard me – David – say) that early-planted early-maturing varieties have very good yield potential if we have a cool and wet July and early-August (not the normal), there is always the risk of poor seed quality.  Only if September is cooler than average and rainfall is not excessive will this system give us good quality seed.  Year in and year out, May-planted late-MG 4 and MG 5 soybean are our best overall choice.  Also, it is rare that double-crop soybean have poor seed quality.
  • Select disease resistant varieties. Most companies do not list resistance to many of our seed diseases, but we have seen differences in varieties.  Look over our final soybean variety test results for more information on seed quality scores and purple seed stain ratings.
  • Select disease-free varieties. Next year, notice your seed quality.  While most companies will not bag disease-ridden seed, some could sneak through.  Seed treatments may be in order.
  • Minimize insect damage to pods. Though not necessary for infection, insect damaged pods are more likely to be colonized by fungal pathogens.
  • What about foliar fungicides? We have not found that foliar fungicides can overcome warm and wet conditions during seed maturation, especially when applied to the R3 stage.  Will a later application help?  That is hard to say. In some cases, applying a fungicide at R5 will improve seed quality, but this is not a sure thing and a yield is unlikely to be improved with later applications.