Field Crop News, Vol. 11:11, May 24, 2011
In This Issue:
- Weather Outlook
- Delayed Pre/Early Post Residual Corn Herbicide Options and Weather Effects
- Fusarium Head Blight Update
- Hybrid Switching Issues
- Corn Club Registration Reminder
- Black Cutworm Damage Starting to Appear
- Potato Leafhoppers Have Arrived in Pennsylvania
- Register and Attend the Penn State Extension Sustainable Cropping Systems Research Tour
- Stink Bugs in Your Soybeans?
Weather Outlook — Paul Knight, Pennsylvania State Climatologist
Wednesday will bring a short break from the showery weather that has produced well above normal rainfall during May in all but the southeastern corner of the state. Partly cloudy skies and a bit lower humidity will yield one good 'drying' day. Very warm and humid air will return on Thursday, accompanied by a few thundershowers in the western half of the state. One of the disturbances from the Midwest will push a cool front into the Commonwealth on Friday leading to more thunderstorms, a few may become severe in the eastern half of the state during the evening. It will still be uncomfortably humid on Friday. The cool front will stall and dissipate across the region during the first half of the weekend leading to more clouds than sun and a scattering of afternoon and evening thundershowers (though it will only rain for an hour or two at most places).
High pressure will steadily build into the mid-Atlantic region early next week setting the stage for a rather sultry start to the month of June. Expect a mini-heat wave with parts of Pennsylvania registering temperatures above 90F on three consecutive days during next week (between Mon–Fri). A more seasonable or even cooler than normal regime will settle in for the start of summer and much of July. Odds favor a wetter than average summer, particularly in the eastern half of the state and flooding risk may be high in August or early September.
Delayed Pre/Early Post Residual Corn Herbicide Options and Weather Effects — Dwight Lingenfelter, Penn State Weed Science
Timely herbicide applications have been extremely difficult, if even possible, with the wet weather. In some cases, the corn is already coming up and no herbicides including a burndown have been applied. Unless it’s Roundup Ready or Liberty Link corn, the options for broadspectrum burndown in this circumstance are very limited. (We do not recommend application of Gramoxone, even if the corn is in spike stage, but would suggest other herbicide tank mixes or using 2-pass herbicide programs.) There are a number of herbicides, including residual products, that can be applied after planting and until corn and weeds reach a certain size or growth stage. The greatest risk of failure comes with trying to control annual grasses such as foxtail and panicum as they are emerging without including a foliar applied herbicide. Product like Prowl, Dual, Harness, Outlook, etc. do not control emerged weeds, so additional herbicides will need to be included in the mixture that control existing weeds.
With the increasing acres of Roundup Ready (glyphosate) and Liberty Link (Ignite) corn, we have more flexibility in how we manage weeds after emergence. In addition, a number of “conventional corn” products are available to control emerged grasses (e.g., Accent Q, Basis, Capreno, Equip, Impact, Laudis, Option, Resolve Q, Steadfast ATZ, and Steadfast Q) and even more are available for broadleaf weed control. In most cases, these POST or foliar-applied herbicides can be tank-mixed with residual products to provide several weeks of control.
For most products, do not apply in a liquid fertilizer carrier if corn has emerged or injury may occur. Maximum corn and weed sizes vary for early POST herbicide applications in corn depending on the product. Herbicides such as Balance Pro, Prequel, Radius, and Princep must be applied before corn emergence. Balance Flexx and Corvus contain a safener and can be applied up to early POST (V2 growth stage) to corn. Other herbicides such as Bicep II Magnum, Bullet, Dual II Magnum, etc. can be applied to corn up to 5 inches tall. Acetochlor-containing products such as Degree (Xtra), Harness (Xtra), FulTime, Keystone (LA), and SureStart/TripleFlex can be applied to corn up to 11 inches tall. Herbicides including Atrazine, Lumax, Lexar, Guardsman Max, and Resolve can be applied to corn up to 12 inches tall (20 inches tall for Resolve Q). And finally, Prowl H2O and Halex GT can be applied to 30 inch tall corn or less. Keep in mind, when tank-mixing with other pesticides follow the most restrictive product label. For a listing of additional herbicides and maximum corn heights and information on maximum weeds sizes for these products pleaser refer to Table 2.2-12 in the Penn State Agronomy Guide and check the most recent herbicide label for specific use guidelines. (Or refer to the herbicide label for additional use information — www.cdms.net or www.greenbook.net).
Stressed crops and herbicide injury: Due to the rainy and cloudy weather, the crops have been struggling to grow and likely will be more sensitive to postemergence applications. Certain formulations such as EC (emulsifiable concentrates) formulations as compared to encapsulated formulations (CS and ME) can cause more injury. For example, Degree Xtra and Prowl H2O are generally safer on emerged corn as compared to their counterparts Harness Xtra and Prowl 3.3EC, respectively. Also there is an increased crop injury potential when combining residual herbicides with loaded glyphosate products or adding additional adjuvants to the spray mix. Regarding application timing after environmental stress, the general rule of thumb is to allow a few sunny days to pass after coming out of a rainy, cool period before applying herbicides (but we may not have that luxury this season). Since the plants are stressed, this allows them time to build up a thicker leaf surface and to get their metabolic processes functioning at a faster pace to detoxify the herbicide. Also, with all the moisture, warmer temperatures, and eventual sunlight, the plants will be growing very quickly and are succulent, so consider using nonionic surfactant (NIS) instead of crop oil concentrate (COC) or methylated seed oil (MSO) as the spray additive.
Heavy rainfall and herbicides: In those areas with regionalized heavy rainfall and flooded fields, if residual herbicides were already applied and water (and soil) is moving off of the field, some of the herbicide will likely be taken with it or it will simply degrade and lose activity. Over the next few weeks monitor those fields for lack of weed control or weed escapes. Post herbicide applications may be necessary for appropriate weed control. If a field needs to be replanted to corn or another crop, remember to adhere to the crop rotation guidelines of the most restrictive herbicide that was applied. Refer to Table 2.2-17 in the Penn State Agronomy Guide or the product label.
Fusarium Head Blight Update — Alyssa Collins, Southeast Agricultural Research & Extension Center
Fusarium head blight (a.k.a. head scab) is a disease of wheat and barley that can lead to the production of toxins in grains. The fungus that causes this disease enters through the flowers and infects the developing grain. Warm, humid environmental conditions at wheat or barley flowering favor the development of this disease.
Most counties of PA are now at “High” to “Medium” risk for the development of scab in wheat and barley that is currently flowering. Our current weather forecast includes a chance of rain nearly every day, so certain areas may have weather that is conducive to the production and spread of spores. Be prepared to spray a fungicide on fields that are at medium to high risk at flowering. Remember, sprays applied PRIOR to flowering will NOT provide significant suppression of scab or toxin production. Caramba, Proline or Prosaro are effective on scab and give control of most leaf diseases and glume blotch. They do not need to be tank mixed with another product to control these diseases. If these products are unavailable, Proline and Folicur (which together provide the same chemicals as Prosaro) may be tank mixed at a rate of 3 + 3 fl oz/A. Spray nozzles should be angled at 30° down from horizontal, toward the grain heads, using forward — and backward mounted nozzles or nozzles with a two directional spray, such as Twinjet nozzles.
Wheat that is about 5 days or more past initial flowering cannot be treated. The labels state the last stage of application is mid-flower and there is a 30-day to harvest restriction. Do not use any of the strobilurins (Quadris, Headline), or strobilurin/triazole (Twinline, Quilt, Stratego) combination products at flowering or later. There is evidence that they may cause an increase in mycotoxin production. Here is a chart to help tease out the best fungicide depending on what other diseases may be present in a given field.
At this point in the season, the only way to reduce the scab problem is to spray. But in general, do not rely solely on fungicides, as they will provide at most a 50–60% reduction in scab severity and vomitoxin. A combination of choosing resistant wheat varieties, avoiding planting into corn or small grain stubble and residue management are also required combating this problem long-term.
Keeping an eye on the FHB Risk Assessment Tool will become critical for those farmers who have wheat beginning to flower late this week and into the next two weeks. As the week goes on, many counties in the northern region drop to a “Low” risk level, and may not need treatment at flowering. This forecasting site, at, is an online model that helps us predict infection risk levels everywhere in the state. Visit it at your convenience, or sign up to have updates e-mailed or texted directly to you. The maps on this site update at approximately 10:15am daily, so check back if you receive a “No Data“ message.
The full extent of symptom expression is usually evident 21 days following infection, which will occur sometime next month for most fields in the state. Symptoms include bleached kernels (called tombstones) that are distinct from healthy green tissue (Figure 1). The level of scab in fields that begin to flower this week will not be clear until mid to late June. Since fungicides do not completely protect the plant, and fields that are past flowering can get some infection, it is recommended that areas that are designated as medium to high risk be harvested with a high fan speed on the combine. This will clean out some of the infected seed that tends to be lighter and will reduce the toxin level in the final product. A source list for commercially available mycotoxin test kits can be found here.
Hybrid Switching Issue — Greg Roth, Grain Crop Management
Its late May, it’s raining, and there is still much corn to plant. Its time not to panic, but to start thinking about hybrid maturities. Most folks have been gradually moving to earlier hybrids, which is good. Many producers have heeded our advice in the past and have a portfolio of hybrids that vary in maturity from full, medium and early hybrids for their area.
Our hybrid maturity predictions are complicated due to our diverse landscape and maturities, but generally speaking, now is the time to start considering moving out of the longest season hybrids in your lineup. Once we get into June, then we need to be thinking about moving to the traditionally earlier season hybrids.
At our research farm in, and our corn maturity zone 2 in general, 109–110 day RM hybrids would be considered full season, 105-108 day mid season and 100-104 day might be considered early season hybrids. Based on a May 25 planting date, we have about 2300 GDDs remaining until October 10, which is a typical frost date in the State College area. The fuller season hybrids, rated at 2600 GDDs, may struggle to mature, even if they adapt to late planting with a 200 GDD reduction as we, and others, have noted in the past. Midseason hybrids, would require less GDDs, approximately 25/day RM, according to my colleague Bob Nielsen at Purdue (http://bit.ly/lm1fmm) or about 2500 for a 105 day hybrid. These hybrids have a better chance of adapting to the late planting and reaching maturity before frost. By June 2, typical available GDDs in this area drop to 2160, so then even the mid season hybrids will have a little trouble catching up, so considering some shift to the early hybrids will become more appropriate in early June. Similar patterns exist in the other maturity zones in our state. You can review GDD accumulations for various locations at two commercial sites: http://bit.ly/iEv6cK and http://bit.ly/jKf8hq.
There is a limit to the amount of switching hybrids that is possible and switching to unadapted hybrids may not be profitable anyway. Also, note that hybrids of the same maturity can vary in their GDD requirement, as some are late flowering with a rapid dry-down. Work with your seed dealers to decide which hybrids are best candidates for switching from and to.
We can often produce sound grain when corn does not reach physiological maturity, but gets at least to ¾ milkline. But there is an increasing risk of lower test weight, a long slow dry down and ear molds with this situation. All of these issues are a function of the remaining growing season and a warm summer could help eliminate.
Finally, remember that we have much more flexibility with silage and high moisture ear and shelled corn options in terms of maturity and use of these options can limit the need for hybrid switching.
5-Acre Corn Club Registration Online — Greg Roth, Grain Crop Management
Registration for the Five Acre Corn Club is now open. This has been an interesting program for many of us for many years, recognizing producers for high yields, collaborating with the PA Corn Growers Association and learning about management on high yield corn sites. This year we are using a new, simple online system for registration that allows producers or their advisors to register them with a credit card. Fields need to be identified at registration. For rules and registration information see the Corn Club website.
Black Cutworm Damage Starting to Appear — John Tooker, Penn State Entomology Specialist
We are starting to get reports of black cutworm damage from a few spots across Pennsylvania. These reports from Union and Franklin Counties indicate that it is time to scout fields, particularly in the southern half of the state, for cutting damage. Well-timed scouting and spot rescue treatments are usually the most economical tactic for managing black cutworm.
Penn State’s Black Cutworm Monitoring Network initially detected three significant flights of black cutworm moths: Berks County near Kutztown, Fulton County near McConnellsburg, and northwestern Lehigh County. The degree-day accumulations for these three sites are above 300, so cutting damage should be evident if it is going to happen.
Subsequent to these three flights, we have also detected significant flights in Northampton, Union, and southern Centre Counties. Degree-day accumulations for these sites are 90, 95, and 220, respectively, so scouting in these locations should happen next week at the latest. For more details on black cutworm, its biology and management options see our fact sheet and for details on degree-day accumulation in your part of the state see the PA-PIPE (Pennsylvania Pest Information Platform for Extension and Education) system; once on the site, choose ‘Public Map’ and then scroll down to find the insect pest models and black cutworm.
Potato Leafhoppers Have Arrived in PA — Paul H. Craig, Agronomy, Dauphin County
Today, May 24th marked the first observation of adult potato leafhoppers (PLH) on my truck in Upper Dauphin County. It seems like our recent weather patterns have not only brought central PA significant amounts of rainfall but also early arrivals of PLH as well. Leafhoppers are small, pale or yellowish green insects. The adults can fly but the nymphs, which closely resemble the adults, cannot fly. They are considered the number one economic pest of alfalfa across the US.
Entomologists who study PLH tell us that about 70% of these early arriving leafhoppers are pregnant females that quickly deposit their eggs in such crops as alfalfa, potatoes, soybeans and on trees such as locust and maples. Once in PA this insect pest has a rapid population growth potential. Females will lay 3 to 7 eggs/day for 30 or more days. Within 3 weeks the eggs will have hatched, the nymph grown into maturity and new adults repeating the cycle by laying more eggs. Because the female lays eggs for 30 days populations are always overlapping and can double in size in 10 days or less.
Register and Attend the Penn State Extension Sustainable Cropping Systems Research Tour, June 22, 2011 — Craig Altemose, Agronomy, Centre County
Come learn about innovative cropping systems designed to produce all the feed, forage, and fuel for a dairy farm. See diverse crop rotations that use no-till, legumes, cover crops, and green manures. Learn about ecological and innovative strategies designed to reduce off-farm inputs and minimize environmental impacts. Strategies include manure injection, multiple weed control strategies that reduce herbicide inputs, cover crops and high residue cultivation, canola to fuel a straight vegetable-oil powered tractor and for livestock protein, and integrated slug and insect management. Pesticide Applicator Recertification Credits, Certified Crop Advisor CEU’s, Manure Hauler Certification Credits, and Certified Nutrient Management Credits will be available. The tour will take place on June 22 from 9 am to 3 pm at the Samuel E. Hayes, Jr. Livestock Evaluation Center, 1494 Pine Grove Road, Pennsylvania Furnace, PA 16865 (just east of the Penn State Rock Springs Agronomy Research Farm, Centre County). The tour costs $10 and includes lunch.
To register and learn the details, visit http://extension.psu.edu/sustainable-cropping-systems or call toll-free 877-489-1398.
Stink Bug in Your Soybeans? — Jeff Graybill, Agronomy, Lancaster County
Many Soybean growers were caught unaware of the growing presence of the Brown Marmorated Sting Bug in their soybean fields last August. Today, this new pest is probably more widespread in the media than in some fields; however, it is a very real threat to many if not most of our crops here in Pennsylvania.
Soy growers have a legitimate concern for both yield and quality loses stemming from this pest. To meet this challenge, the PA Soybean Board recently funded a Penn State effort to intensively scout soybeans within South-central and Southeast PA. These funds have hired a summer intern to work with soybean growers, extension educators and local crop scouts to monitor stink bug populations. We hope to not only monitor this pest but develop thresholds for recommending control action as well.
Dr. John Tooker, Penn State Extension Entomologist is developing a scouting protocol which will be used for this project. The summer intern is Kurt Martin, who graduated from the college of Agricultural Sciences at Penn State University this spring. Kurt will be working out of the Lancaster office and will be scouting specific fields in the region. He would also like to receive reports from others as the season progresses. I will disseminate the protocol in the near future which can be used by others to help us monitor the development of this pest. As information is collected and analyzed we will issue any alerts via the Field Crop News.
Contributors: Extension Educators: Jennifer Bratthauar (Franklin), Mike Fournier (Bucks), Joel Hunter (Crawford), Del Voight (Lebanon), Bill Waltman (Potter), Dwane Miller (Schuylkill), Jeff Graybill (Lancaster), Paul Craig (Dauphin); Dept. Crop & Soil Sciences: Doug Beegle, Alyssa Collins, Sjoerd Duiker, Marvin Hall, Greg Roth, Dwight Lingenfelter & John Tooker
Editor: Mark Madden, Sullivan County