Soybeans

As soybeans begin the pod fill growth stages, heat and drought stresses can trigger the development of many disease symptoms. Currently we are seeing many instances of stem diseases in soybean. Many pathogens are associated with stem diseases in soybean, and many produce very similar foliar symptoms, which is why diagnosis from foliar symptoms alone typically leads to a misdiagnosis. Submit questionable samples to the UMD Plant Diagnostic Lab for proper identification. Common soybean stem diseases and their symptoms/signs are outlined below.

Soybeans: Continue scouting for corn earworm, stink bugs, and soybean looper in double-crop fields. Defoliation thresholds at R5 are 15% and between 20 and 30% at R6. Corn earworm pheromone trapping information for Maryland can be found at https://extension.umd.edu/resource/corn-earworm-pheromone-trapping. NC State Extension has a good CEW threshold calculator can be used to help decide if it is worth treating: https://www.ces.ncsu.edu/wp-content/uploads/2017/08/CEW-calculator-v0.006.html. Stink bug thresholds are 5 bugs per 15 sweeps until the soybeans reach the R7 stage, after which treatment for stink bugs is not necessary. 

Current corn earworm pheromone trap captures in Maryland and Delaware and pest management recommendations.

As planting gets underway, it is important to stay on top of our most troublesome weeds. In particular, marestail/horseweed, common ragweed, and Palmer amaranth. Below are two new charts to help determine the type of products to be included in the tank mix to best manage these weeds in corn and soybean.

As soybean plants mature, tolerance for defoliating pests drops from about 30-35% during the vegetative stages to closer to 15-20% during the reproductive stages (flowering and pod fill). Any defoliation can look worrying, but it is hard to accurately measure defoliation. Most people tend to overestimate damage in three ways: overestimating the leaf area lost, not taking the full plant canopy into consideration, and not sampling the field randomly. Luckily, there are some great new tools to help you measure accurately and train your eye. Accurate measurement is the key to avoiding unnecessary treatments, saving you money, time, and preserving beneficials.

August IPM insect scouting tips on soybean, field corn, and sorghum.

Agronomy News is a statewide newsletter for farmers, consultants, researchers, and educators interested in grain and row crop forage production systems. The topic for this edition is Cost-Share Grants Expanded, Evaluating Wheat Stands, Fusarium Head Blight Management, Early-Season Wheat Disease Scouting, April IPM Insect Scouting Tips, Cover Crop Termination for 2021, Maryland Circuit Court Judge Reverses Final Maryland AFO Permit, Maryland Ag Land Preservation, Pesticide Disposal Program, Pesticide Recertification Workbook, US Corn & Soybean Planting Acreage Report, Cooperators Needed For On-Farm Nitrogen Trials, What To Do With Thinning Alfalfa Stands, Weather Outlook, and Regional Crop Reports.

Agronomy News is a statewide newsletter for farmers, consultants, researchers, and educators interested in grain and row crop forage production systems. The topics for this edition are

Agronomy News is a statewide newsletter for farmers, consultants, researchers, and educators interested in grain and row crop forage production systems. The topic for this edition is Double Crop Beans, Not So Fast, Herbicide Field Day, July IPM Insect Scouting Tips, Hemp Twilight Tour, Corn Disease Update, 4R Field Day, Poison Hemlock Identification and Management, Tar Spot: New Disease of Corn, Soybean Board Field Day, 2021-2022 Cover Crop Sign-Up, LEAD Maryland Fellowship Applications, Maryland Commodity Classic, MDA Pesticide Exams, MDA Pesticide Disposal Program, Weather Outlook, and Regional Crop Reports.

With barley harvest behind us and wheat harvest in full swing, our thoughts move to planting double-crop soybeans. This might be a prudent decision in many cases, but if you need forage, it may be a short-sighted choice. I suggest you look into your toolbox and consider forage sorghum, millet, or even grain sorghum.