Herbicide Resistant Weeds Workshop

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Palmer amaranth infesting a soybean field
The workshops will be virtual via Zoom on Tuesday Dec. 8th and Tuesday Dec. 15th. On both days, choose the time that works best for you: 8-10 am OR 6-8 pm. Optional in-person “watch party” meetings offered at several locations.

Register at: https://go.umd.edu/IWM  

Topics: Session One: Tues Dec 8th 8-10 am OR 6-8 pm
Herbicide Resistance- What is It?
Mechanisms of Action-How to Choose Herbicides
Creating Effective Herbicide Plans  

Session Two: Tues Dec 15th 8-10 am OR 6-8 pm
IWM with a focus on Palmer Amaranth, Common Ragweed, and Marestail
Local Perspectives on Resistance Management
Putting It All Together: Creating a Weed Management Plan

Speakers:
Dr. Michael Flessner and Dr. Vijay Singh, Virginia Tech
Dr. Mark VanGessel, University of Delaware
Dr. Kurt Vollmer and Ben Beale, University of Maryland

CCA Credits will be offered.
For More Information Contact:
Ben Beale at 301-475-4481 or Kurt Vollmer at 410-827-8056 28

Fire ants in crop fields and near homes – southeast VA

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Fire ant mound around brace roots of corn plant, Suffolk, VA.

We have high numbers of fire ant mounds in our crop fields and around our farms this year. There have been some unfortunate encounters and this message is to make you aware of what these mounds look like and the potential for injury. Mounds look like large piles of loose dirt (keep in mind they have to start small at some point). They are often found around fence posts and mailboxes, but many are located in fields, pastures, and lawns. Field borders and paths are frequently infested. Fire ants sting, just like wasps and bees, and some people will be allergic and require medical interventions. People that are not allergic will have itchy, painful welts that often fill with fluid and may take days or a week or more to heal. Usually, you will have dozens or even hundreds of stings. This is because the swarm very fast and wait to sting all at once. Keep in mind that I have lived around them most of my adult life in North Carolina and we have come to accept them as part of our environment and have learned caution and awareness. I have been stung multiple times, usually once every few years, and usually when I am scouting crops. Be aware of where your feet are standing. Walk quickly when crossing a field because you can disturb them and get away without injury. Treatment options are below for mounds located near homes and barns. You do not want children or young animals near these things.

Fire ant mound around edge of soybean field, Suffolk, VA.

I would not attempt to clear your crop fields. A single acre can contain hundreds of mounds and millions of fire ants. Fire ants are predators and will eat caterpillars and other insect pests. They will not eat seeds and plants. Large mounds can damage equipment in rare cases. Products exist that can be applied to turf and lawns with year-long residuals (e.g., TopChoice). These products require a pesticide applicator license to purchase. Baits (e.g., Advion) are an alternative if you are not licensed to apply insecticides. These can be purchased online, many local retailers do not carry them yet. Surface treatments do not work because the colony can live very deep underground. Do not attempt to treat once the weather turns cold because it will not work. Wait until spring. Pray for a cold winter.

Be safe y’all and stay healthy. As always, reach out to me if you have questions or concerns. Keep in mind that I am NOT an urban or ornamental entomologist and I am NOT trying to sell you any specific product. FOLLOW THE LABEL WITH ANY INSECTICIDE.

Peanut Maturity in SE Virginia on Sep 28, 2020

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I know I missed a week of updates, but it was not much change in peanut maturity since recently. On Sep 28, however, some fields started looking close to digging. While some fields in theory still need three weeks to mature, others can be dug soon (see picture below showing samples of ‘Sullivan’ peanut planted at about the same time but in different fields with different conditions through the summer).

Maturity of peanut in Isle of Weight County, VA, on Sep 28, 2020. Samples are from different fields planted with Sullivan in mid-May.

Similarly, cultivar ‘Bailey’ showed variable maturities depending on the soil type, growth conditions, and irrigation. But in majority of approximately 35 samples looked at on Sep 28, Bailey seemed ready to dig starting within the first week of October.

With the exception of Bailey, peanut cultivars currently grown in Virginia have the high oleic oil chemistry. Thus, it is important to realize that cooler temperatures at this time of completing maturity may affect the high oleic oil chemistry.  Research showed that temperatures in the range of 85 to 90 F during pod filling to harvest increased the oleic fatty acid content, which makes peanut a high oleic peanut; while lower temperatures promoted the linoleic fatty acid.  I hope not, but if research proves right for our late maturing peanut this fall, when temperatures dropped in high 60’s or at the most 70’s for the past 3-4 weeks, this determination should be made as soon as first peanuts are picked and measures taken. This is particularly important for Virginian growers that primarily grow peanut for certified seed production.

Sample of ‘Bailey’ peanut in Isle of Weight County, VA, on Sep 28, 2020.

Corn earworm report–September 24, 2020

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Corn earworm moth black light trap catches were low this week, averaging from 2 to 6 per night (Greensville=3; Hanover=2; Southampton=6; Suffolk=2). Most trap operators will be shutting off their traps by the end of this month. We greatly appreciate the efforts of cooperating growers, Virginia Cooperative Extension Agents Mike Parrish, Sara Rutherford, Laura Maxey-Nay, Scott Reiter, and Josh Holland, and Tidewater Agricultural Research and Extension Center’s Daniel Espinosa. TABLE

Peanut Maturity in SE Virginia on Sep 15, 2020

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Frank Bryant pod blasting the peanut pods (left) and growers commenting on the pod samples (right).

Monday, Sep 14 2020, Extension Agent Livvy Preisser organized a pod blasting clinic in Windsor, VA, at the Indika Farms Inc.

As every year my technician, Frank Bryant, assisted the Agent with this activity. Keeping the distance, several growers brought over 25 peanut samples from almost 2000 acres from the neighboring fields.

In average, peanut still needs 3 weeks or longer to complete physiological maturity, regardless if the fields were or not irrigated. From all, only one sample of non-irrigated Sullivan was 2 weeks closer to digging.  This agrees with what we have observed in the research plots this week.

Maturity of peanut in Isle of Wight County, VA, on Sep 14, 2020. Samples are from different fields, Bailey (upper left and center), Bailey II (upper right), and Sullivan (below).

Additional pod blasting clinics will take place on Sep 16 at Carolina Easter, Courtland, VA; Sep 18 at Meherrin Ag. & Chemical, Capron, VA; Sep 22 at TAREC, Suffolk, VA; Sep 23 at Carolina Eastern, Courtland, VA; Sep 25 at Meherrin Ag. & Chemical, Newsoms, VA; and Sep 28, at Indika Farms Inc, Windsor, VA. They are organized by Extension Agents Livvy Preisser, Elisabeth Pittman, and Josh Holland.

Because temperatures of the past 3 weeks seem to decrease in the next 3 weeks and into the Fall by 15 to 20 F daily, from high 80s and on some days mid-90s to only mid-70s, the rate of pod development from immature (white mesocarp color) to mature (brown and black color) will decrease as well. Therefore, patience is needed with peanut crop this Fall for harvesting high yields and SMK in Virginia.  

Corn earworm report–Sep. 10, 2020

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Average nightly corn earworm/bollworm moth black light trap captures for this week were: Greensville=28; Prince George-Templeton=5.5; Prince George-Disputanta=7; Southampton=17; Suffolk=76. Here is the Table

For soybean, here is the tool that calculates the corn earworm larval threshold number based on user input values for sampling techinque (sweep net or beat cloth), cost of insecticide application, price of beans, and row width: threshold calculator

We have done 391 vial tests so far this season, with 35% of moths surviving the 24-hour exposure to the pyrethroid cypermethrin at the rate of 5 micrograms per vial.

Peanut Maturity in SE Virginia on Sep 8, 2020

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In the past two weeks, peanut progressed nicely towards harvest maturity. The pictures below show maturity of Bailey on Aug 25 and Sep 8, 2020; and maturity of Sullivan and Emery on Sep 8, in fields at the Tidewater AREC, Suffolk, VA. Recent good soil moisture and high temperatures, not many exceeding 95 F, seem to close the gap between last and this year’s harvest time.  It is, still, very improbable to have an early digging, like we have had in the past two years when peanut was complete dug by end of Sep in Virginia. Maybe by the end of Sep, 2020, we will start digging some early planted fields. I will provide weekly updates.

Bailey planted May 14, 2020 and pod blasted on Aug 25 (left) and Sep 8 (right), 2020.

Emery (left) and Sullivan (right) planted on May 14 and pod blasted on Sep 8, 2020.

Damaged kernels probably from earlier noticed pods with Southern Corn Rootworm and other damage.

Pickleworm found in Virginia – a pest threat to pumpkins, squash and other cucurbit crops

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This week, my PhD student, Sean Boyle, observed pickleworm holes in our zucchini and squash in Whitethorne, VA near Blacksburg. This is the first that we’ve seen this pest in 2020. If you have noticed this pest in your area, please let me know – email tkuhar@vt.edu. The pickleworm, Diaphania nitidalis (Stoll) is a tropical moth pest of cucurbit crops including pumpkins, squash, and cucumbers (Fig. 1). It is typically a pest in the southern U.S. and does not overwinter in Virginia. The past few years, the pest has made its way northward in late summer on wind and storm fronts. Several pumpkins growers in Virginia have suffered damage from this pest in since 2017 usually following some August summer storms.   

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Fig. 1. Pickleworm moth.
Fig. 2. Pickleworm larva and entrance hole on pumpkin.

Moths fly to flowering pumpkins, squash, or cucumbers and deposit their eggs. A single female moth can lay up to 400 eggs usually on cucurbit flowers.  Larvae feed on flowers (Fig. 2) and bore into fruit leaving a characteristic perfectly round hole often with sawdust-like fecal material around it as well.     

Management. Pickleworm is very difficult to predict or monitor for as eggs are very tiny, moths fly at night, but are not attracted to lights, and there is no commercially-available pheromone lure.  As a result, cucurbit growers in the South often apply insecticides weekly during the fruiting stages until final harvest.  Pyrethroid insecticides can be effective at controlling this pest if sprayed in a timely manner (i.e., lambda-cyhalothrin, permethrin, bifenthrin, Baythroid XL, Mustang Max, etc.). Pyrethroids are often used because of their low cost and because they also control squash bugs and cucumber beetles, but they are not IPM compatible and can result in outbreaks of secondary pests such as aphids.  Usually two or more sprays of pyrethroids in late summer can cause severe aphid problems leading to honey dew build up on plants. Other insecticides that control pickleworm include: the spinosyn productss, Radiant and Entrust, the diamide insecticides, Coragen and Harvanta, the insect growth regulator (IGR) Intrepid, and the lepidopteran-targeting insecticide Avaunt eVo.  All of these products will have less nontarget impacts than pyrethroids and will also control pickleworm.