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.
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 (email@example.com).
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 (firstname.lastname@example.org). The 2019 Fungicide Efficacy Table for Wheat can be downloaded below.
As you may have heard, the EPA announced Wednesday (Oct. 31, 2018) to continue dicamba registrations for over-the-top use in Xtend soybeans and cotton, through 2020, with label changes. This decision only impacts Xtendimax, Engenia, and FeXapan dicamba products. The decision does not impact dicamba products that are not labeled for over-the-top use in Xtend soybeans or XtendFlex cotton.
Summary of label changes from the EPA:
- Two-year registration (until December 20, 2020)
- Only certified applicators may apply dicamba over the top (those working under the supervision of a certified applicator may no longer make applications)
- Prohibit over-the-top application of dicamba on soybeans 45 days after planting and cotton 60 days after planting
- For cotton, limit the number of over-the-top applications from 4 to 2 (soybeans remain at 2 OTT applications)
- Applications will be allowed only from 1 hour after sunrise to 2 hours before sunset
- In counties where endangered species may exist, the downwind buffer will remain at 110 feet and there will be a new 57-foot buffer around the other sides of the field (the 110-foot downwind buffer applies to all applications, not just in counties where endangered species may exist)
- Clarify training period for 2019 and beyond, ensuring consistency across all three products
- Enhanced tank clean out instructions for the entire system
- Enhanced label to improve applicator awareness on the impact of low pH’s on the potential volatility of dicamba
- Label clean up and consistency to improve compliance and enforceability
A more detailed press release with links to more information from the EPA is here: https://www.epa.gov/newsreleases/epa-announces-changes-dicamba-registration.
Annual dicamba-specific training is still required for the use of these products, in addition to a private or commercial pesticide applicators license. Therefore, training completed in 2018 needs to be repeated to legally apply in 2019. In Virginia, trainings will delivered by the registrants (BASF, Bayer, or Corteva) both in-person and online. I will post further details on when, where, or how to schedule a training as these details become available. Training requirements to apply these products in North Carolina were different than Virginia for 2018, which I anticipate will continue in 2019.
In the past, Virginia Department of Agriculture and Consumer Services Office of Pesticide Services has not placed additional restrictions, beyond the EPA approved federal label, on these products. I do not anticipate a change in that stance for 2019.
Prepared By: Tom Kuhar, Adam Formella (Entomology graduate student), and Sally Taylor (TAREC)
Over the past two weeks fall armyworm outbreaks have occurred in southwest Virginia with reports from Abingdon to Roanoke, VA in turfgrass and small grain crops. Some new plantings of rye have been completely destroyed and densities of armyworms have exceeded 10 per square foot in some areas.
Fall armyworm (Spodoptera frugiperda) is a tropical moth native to warm climate areas of the western hemisphere. It cannot successfully overwinter in Virginia. However, this armyworm moth (see Fig. 9) is a strong flier, and populations can migrate throughout the eastern United States in the late summer and fall months, sometimes in very high populations like what recently occurred in southwest Virginia. Phil Blevins (VCE ANR Agent in Washington Co.) was monitoring a fall armyworm bucket trap for us in sweet corn in Abingdon, VA, and 2-3 weeks ago detected a huge jump in moth catch. This was a harbinger of things to come. Female FAW moths can lay up to 10 egg masses (each with 100 – 200 eggs) (see Figs 1-2). So, it’s no surprise how quickly the densities of armyworms can build up from just a few egg laying moths in a field.
Fall armyworm can feed on a number of different host plants, but prefers grasses, small grains, corn, and sorghum. Turfgrass has been particularly hit hard by this pest this week around the New River Valley. In turf, FAW larvae can consume all above-ground plant matter causing noticeable damage and bare spots. This can happen quickly.
Insecticides recommended for control include most pyrethroids (such as bifenthrin, lambda-cyhalothrin, Mustang Max, Baythroid XL, etc..), Lannate LV, and many of the more selective (lepidopteran-targeting) insecticides such as the diamide Prevathon, Coragen, Acelepryn, Besiege), indoxacarb products like Steward, Avaunt eVo, Provaunt, spinosad (Blackhawk, Tracer, Matchpoint), Radiant, Intrepid Edge, as well others. Consult the relevant Pest management Guide for specific recommendations on the various commodities. Please note that control of large larvae is sometimes difficult with any insecticide. Link to the VCE Pest Management Guides for Field Crops, Vegetables, and Turf are provided below.
Links to Pest Management Guides
Luginbill P. 1928. The fall armyworm. USDA Tech. Bull. No. 34.
Although most of our sweet corn has been harvested for 2018, there are still some late-planted fields that may still be at risk to insect attack. While most of the remaining pheromone traps around the state had low catch numbers, Mark Sutphin VCE Frederick County saw a great jump in corn earworm catch this week at one of the farms still growing sweet corn. Keep in mind that corn earworm is also a pest of many other crops that may still be at risk this fall including tomatoes and beans (See images below).
Please keep in mind, In an effort to fend off any more pyrethroid insecticide resistance development in our corn earworm populations, rotating to another insecticide than a Class 3 (pyrethroid) is highly encouraged for at least one spray. Diamide insecticides such as Coragen or Besiege, the carbamate Lannate LV, or the spinosyn Blackhawk, are all effective non-pyrethroid options.
Also, Phil Blevins VCE Washington County reported some of the highest fall armyworm catch of the year >200 moths in the bucket trap this week. These moths showed up late to southwest Virginia and are probably not going to be much of a pest concern in the state, and they will not successfully overwinter here as they are a tropical moth.
This will be final trap catch alert of the year for the sweet corn IPM program as most corn has been harvested. I want to thank all of the VCE Extension folks who monitored traps on farms in their respective counties this year: Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Eastern Shore AREC Entomologist, Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).
Click on the table below to view the trap catch results (moths per night) for some of the locations around Virginia for this final week. We will send out a synopsis of the season this winter. We are still seeing some high corn earworm moth activity on the Eastern Shore of Virginia, Westmoreland County on the Northern Neck, and Frederick County in the northwestern portion of our state. With the hot weather that we’ve experienced the past 2 weeks, moth activity has probably been a little higher than usual for September. Sweet corn growers are advised to keep control measures (spray intervals) as they were during August in most counties.
We still have caught very few fall armyworm moths in our traps around Virginia; however, this insect could contribute to some infestations in the ears of late corn. In an effort to fend off any more pyrethroid insecticide resistance development in our corn earworm populations, rotating to another insecticide than a Class 3 (pyrethroid) is highly encouraged for at least one spray. Diamide insecticides such as Coragen or Besiege, the carbamate Lannate LV, or the spinosyn Blackhawk, are all effective non-pyrethroid options.
Registration is open for the 2018 Mid-Atlantic Crop Management School for Certified Crop Adviser, Nutrient Management, and Pesticide Applicator Credits for Virginia, Delaware, Maryland, West Virginia, and Pennsylvania. The venue is the Princess Royale Oceanfront Hotel and Conference Center in Ocean City, MD on November 13-15, 2018. Register early so you can enroll in your preferred classes!
Soybean loopers have reared their ugly heads across southeastern and coastal Virginia this week. With many of us busy hauling corn, it is reasonable to ask – when can we stop spraying beans?
In a normal year, we could safely ignore mid-September infestations. This year, the majority of double crop Virginia fields are completing pod fill. Research indicates that R3-R5 beans benefit from a spray when defoliation reaches 15% and you find more than 1 looper per sweep. I recommend that you at least double, and can safely triple, this threshold in R6 beans (i.e., 35-50% defoliation is acceptable). It benefits you to exercise restraint when treating fields after R5.5. There is no scenario when you need to spray R7 beans for loopers. Cooler evening temperatures will work in our favor when they arrive.
In Virginia, Intrepid Edge and Steward have been our most consistent treatments (see image below from 2017). Looper populations in Virginia have tested diamide resistant the past two years (e.g., Besiege, Prevathon). Spraying pyrethoids will only make the problem worse.
In general, we’ve had a good, but not great year for soybean in Virginia. Although many areas were hit with a 3 to 4 week dry spell during July, August rains kept us in the game. However, we did not see the ample rains or cool temperatures that we experienced in August of 2017, which resulting in record yields. Below is a summary of August rainfall and temperature anomalies for the U.S.
As you’ll notice, we had about average or slightly below average precipitation and average to slightly above average temperatures for most of Virginia’s soybean growing areas.
So, I do not suspect that our yields will be as good as last year. Still, our earlier-maturing varieties planted in April or May should yield quite respectably considering that most have made over 50% of their yield – they have reached the R6 stage (see photo below). Yield of our later-maturing varieties, planted in May and early June, and our double-crop plantings are not quite there yet – much of our yield is yet to be determined – R5 soybean have only made roughly 25% of their yield at that time.
So, what do we need for good yields? Rain is obvious. Full-canopied plants with adequate soil moisture will draw about 0.25 inches of water/day from the soil. But, we also need cool temperatures – soybean do not generally like 90+ degree days, especially when forming seed.
Below is the 10 day rainfall and temperature forecast for the U.S., and it does not necessarily look good for us. Note that the rainfall is predicted accumulation and the temperature map shows anomaly. Although we should get some rain this weekend only (more in northern parts), temperatures are supposed to be above average. But, forecasts are only forecasts. The weather does change. I hope we will get the needed rainfall that they are predicting this weekend. But a big ridge appears to be setting up over the Mid-Atlantic states for next week. This usually means warm weather and only at the edges of ridges do we normally see rainfall – note the heavy rainfall predicted from Nebraska through Michigan.
I don’t mean to discourage, just to inform. We still have decent soil moisture, at least in the subsoil. With rain this weekend, we should get through next week without too much harm to the crop.
Our double-crop soybean (assuming late maturity group 4’s and group 5’s planted in late June to July) are just now in the R5 stage – it usually takes 80 to 100 days from planting to reach R6, depending on maturity and planting date. So some timely September rains will usually result in good double-crop soybean.
When will our yield be “made”? Below is table showing the number of days to soybean physiological maturity (R7; 95% of yield has made). When can we expect to be harvesting our soybean? Full maturity is reached about 2 weeks after R7 and harvest can proceed after the soybean have dried down to a harvestable moisture, usually within a week after R8.