Average nightly corn earworm/bollworm moth black light trap captures for this week were: Dinwiddie=51; Greensville=9; Hanover=3 (first week with more than 0.5 per night); Prince George-Templeton=12; Prince George-Disputanta=3; Southampton=5; Suffolk=17. Here is the Table. At just over 200 vial tests conducted, corn earworm moth survival is 39%.
Please find the 2020 Virginia Tech Eastern Shore Agricultural Research and Extension Center Virtual Field Day available via YouTube. Pre-recorded sessions can be viewed in one playlist or you can pick and choose individual topics using the hyperlinks in the attached program.
The program with clickable links is found by clicking: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/spes/spes-239/SPES-239.pdf
As always, contact us with questions vis email, YouTube comments, or Facebook. Please let us know of any further research or Extension questions that you may have. We hope to see everyone again at our Painter, VA location in person in Summer 2021!
Stay healthy and take care!
Average nightly corn earworm/bollworm moth black light trap captures for this week were: Dinwiddie = 26; Greensville =4; Prince George-Templeton = 9; Prince George-Disputanta = 6; Southampton = 8; Suffolk = 23. Thanks to our Agents and Growers for their efforts. Here is the data table
Sally Taylor and her entomology program sampled a Cotton Incorporated sponsored planting date experiment today at the Tidewater AREC in Suffolk, VA. We found 2 to 6.5% bollworm-injured bolls in conventional (non-genetically protected against bollworm) cotton. In our Virginia Soybean Board experiment with maturity groups 4 and 5 full-season soybean (beginning pod growth stage), we had 2.3 to 5 corn earworm larvae and up to 3 soybean looper larvae per 15 sweeps.
Over the past couple of weeks our fruiting vegetable crops at Kentland Farm in Whitethorne, Virginia have been invaded by abundant numbers of leaf-footed bugs (Leptoglossus spp.). These bugs that are in the same bug family Coreidae as the squash bug Anasa tristus. They are piercing sucking feeders that have killed entire cucumber and zucchini plants from their feeding on stems and leaves or have caused numerous puncture wounds on fruit, which result in a little fluid oozing from the fruit.
These insect pests can be controlled using the same insecticides that are labeled for use on stink bugs and squash bugs, namely, pyrethroids or neonicotinoids for conventional growers. Organic growers can achieve some suppression of bugs with the use of products containing pyrethrins such as Pyganic or Azera, or with the use of Surround (kaolin clay powder), which also works to prevent sunscald on fruit.
To learn more about this pest, please see the following VCE fact sheet that we produced a decade ago. Wow has it been that long? https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/3012/3012-1522/3012-1522_pdf.pdf
Since early July, we have been monitoring Heliothis traps baited with corn earworm pheromone at on 4 hemp fields and one sweet corn field in and around Montgomery, Co., Virginia. Below are the trap catch results. After a week or two of low catch, the moth activity has picked up especially at the Wall sweet corn.
Corn earworm moths per trap per week
|Week ending||Tru Harvest hemp 1 – Christiansburg, VA||Tru Harvest hemp 2 – Christiansburg, VA||Urban Hort Center – Hemp Blacksburg, VA||Wall Farm – sweet corn Blacksburg, VA||Homefield Farm – hemp Whitethorne, VA||Catawba hemp – Catawba, VA|
Black light trap nightly averages for corn earworm/bollworm moths this week in Virginia were: Greensville = 35.6; Prince George-Templeton = 1.0; Prince George-Disputanta = 3.3; Southampton = 2.0; Suffolk = 17.1 (all reports were higher than last week). Thanks to our Agents for their reports.
Resistance monitoring of corn earworm/bollworm using adult vial tests now has 50% of moths surviving the 24-hour exposure to the pyrethroid, cypermethrin at the 5 microgram/vial rate (76 vials tested to date, collected from Suffolk).
Prior to this week, corn earworm/bollworm moth counts have been low in southeast Virginia black light traps. For this week (July 17-23), average nightly catches of moths were: Greensville = 7.4; Prince George-Templeton = 0.3; Prince George-Disputanta = 0.7; Southampton = 1.5; Suffolk = 7.4. Thanks to the Virginia Cooperative Extension Agents who are operating traps this season.
We have tested 47 corn earworm/bollworm moths since June 23, 2020 in our pyrethroid resistance monitoring program. Moths are captured in pheromone traps and are exposed to 5 micrograms of cypermethrin inside a glass vial for 24 hours, then rated as dead/down/alive. Untreated controls (in acetone-only treated vials) are also evaluated to correct for control mortality. The average for the past month is 43% moth survival. High survival rates indicate an increased chance of pyrethroid control issues and the need to consider alternative chemistries if a spray is needed.
In a non-Bt corn experiment planted on April 9 at our research farm in Suffolk, VA, we had large corn earworm larvae in the ears last week. Now they have exited the ears and are pupating in the soil. It takes about 10 days for the moths to emerge–this flight out of corn is the one that we are concerned with in crops such as soybean, cotton, peanuts, and vegetables–the moths want to lay eggs on a good food source for their larvae. Please check back with the Advisory for more pest updates and recommendations.
I am receiving numerous reports of wheat and barley fields that were severely injured by cold temperatures. The symptoms are completely or mostly blank/absent kernels on entire heads. What I had seen prior to this week manifested as a few missing kernels on the head, or scattered white heads that were obvious freeze injury. These newly symptomatic fields either seem normal or just slightly ‘off’ from the road but on investigation many heads have no grain. In some cases, the stems are beginning to turn brown and die. At this point I think this is in a few local areas and not widespread. It was obviously a combination of low temps and particular fields that were at a very susceptible stage.
I encourage you to assess small grain fields. Any damage is much less severe near edges, roads or lanes, so scout well out into fields. Those with severe damage should contact their crop insurance adjuster or VCE agent ASAP to assess the yield potential in the field.
The dicamba products Xtendimax, Engenia, and FeXapan had their registrations vacated June 3, 2020 by the U.S. Court of Appeals for the Ninth Circuit. The EPA announced June 8, 2020 a final cancellation order for these products.
Existing stocks, in possession on June 3, 2020 (the date of the court’s decision), can be used by farmers and commercial applicators by July 31. Use of these products must be consistent with the previously approved label.
The EPA’s full statement is here: https://www.epa.gov/sites/production/files/2020-06/documents/final_cancellation_order_for_three_dicamba_products.pdf. Details on use of existing stocks are on page 11.
More background information can be found here
Tavium (dicamba + S-metolachlor) is also still legal to use. Tavium was not mentioned in the lawsuit making Tavium the only way to legally apply dicamba to Roundup Ready 2 Xtend soybeans or Xtendflex cotton. This product is already in short supply and may be difficult to acquire. Tavium cannot be used on double crop soybean.
There are effective alternatives to dicamba. In RR2 Xtend soybean, I recommend Flexstar GT in place of dicamba. This product is not currently in short supply, but there is potential for that to occur. So I encourage farmers that plan to use Flexstar GT to go ahead and acquire it. Other alternative products can be found in Table 5.54 on page 5-182 of the Pest Management Guide. Additionally, information on controlling Palmer amaranth in soybean is here: https://www.pubs.ext.vt.edu/2808/2808-1006/2808-1006.html and common ragweed is here: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/spes/spes-143/SPES-143.pdf. In cotton, most varieties have the option of using Liberty, which is my recommendation in place of dicamba. But other alternative products can be found in Tables 5.112 and 5.113, starting on page 5-344.
Farmers should consider changing soybean herbicide traits for double crop acres or any soybean ground that has not yet been planted. LibertyLink, LLGT27, and Enlist are all good options in place of RR2 Xtend. Farmers may also consider a Roundup Ready variety as well, to potentially save tech fees compared to RR2 Xtend, but there are very few of these even before this announcement. I realize changing this late in the year may not be feasible and the best performing varieties may not be available. If farmers choose to change varieties, make sure that the variety has both strong yield potential and the herbicide trait of choice.
This ruling does not apply to dicamba products such as Clarity and Banvel, that are not labeled for use in Xtend traited crops, so these can continue to be used in pastures, corn, and other labeled uses. Dicamba products that are not labeled for use in dicamba-tolerant crops have been and continue to be illegal to use over-the-top of RR2 Xtend soybean and Xtendflex cotton.
This ruling comes at the absolute worst time during the season. There may be temptation to use dicamba illegally, but I strongly encourage us all to think about the implications of such actions on agriculture. These products have been and will continue to be under scrutiny from the non-ag public.
The cool and wetter weather earlier in the month has delayed some soybean planting into June. In addition, some cotton growers have switched to soybean due to the same reason. The question that came to me often this week was “Should I increase my seeding rate?”
In general, our research has not found a dramatic yield response to more seed per acre until mid-June. This largely reflects the lack of decrease in yield due to late planting dates until about the same time. If planted by the first week of June, the soybean usually has time to build a canopy great enough to capture most of the light by flowering, and does not need the extra plants.
However, I usually recommend that you begin increasing seeding rates by about 20,000 seed per week beginning the first of June.
Therefore, I would suggest the following:
This week (June 1-6): 120,000 – 140,000 seed/acre
June 7-13: 140,000-160,000 seed/acre
June 14-20: 160,000-180,000 seed/acre
June 21-27: 180,000-220,000 seed/acre
On your better soils or with later maturing varieties, use the lower seeding rate. On your less-productive soils or with earlier varieties, use the higher rate. This will insure that you you have enough leaf area to maximize the yield for those planting date.