Corn

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.

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.

Listed below are the corn trait packages to make it easier to understand seed guides, sales material and bag tags. It is an abbreviated version of the Bt trait table plus related extension materials free online at: https://www.texasinsects.org/bt-corn-trait-table.html. Information listed Includes the name of each trait package, bag tag code, Bt toxins expressed (Cry1 types and Vip3A for caterpillars, Cry3 types for rootworms), refuge requirement (RIB=% refuge in the bag or REF=% structured refuge) and herbicide tolerance (GLY= glyphosate /Roundup-Ready, LL=glufosinate/Liberty Link, 2,4D or group 1 ‘fops’ type herbicides). Note that older trait packages, with limited or no commercial availability, are listed, so you can look back and interpret previous year’s planting records, seed guides, and research results.

IPM Threshold Guide for Agronomic Field Crops

In order to capture the range of pest pressures and growing conditions in Maryland, we replicated our study across 3 UMD research farms (Keedysville, Beltsville, and Queenstown) and over 3 years (2020-2022). At each location we planted one field of a Bt hybrid and one field of a similarly-yielding non-Bt hybrid as early as possible in the growing season (Table 1). In 2020 our Bt hybrid was LC1196 VT2P (Local Seed, Memphis, TN) which expresses Cry1A.105/Cry2Ab2 proteins. In 2021 and 2022 we planted P1197YHR (Pioneer Hi-bred International. Johnston, IA) which contains Cry1Ab and Cry1F proteins. We planted P1197LR (Pioneer Hi-bred International, Inc. Johnston, IA) for our non-Bt hybrid all three years. All hybrids had excellent yield potential and were grown with standard no-till practices. In each field we established 3 replicates of 3 treatments at planting: 1) an untreated control, with bare seed and no in-furrow product, 2) an in-furrow pyrethroid treatment using Capture LFR® (active ingredient: bifenthrin, rate: 13.6 fl oz/acre), and 3) an NST treatment using Poncho® (active ingredient: clothianidin, rate: 0.25 mg/seed). Each replicate consisted of 24 rows of corn at 30 inch row spacing, and was 200 feet long.

A few hot spots where corn earworm (also known as tomato fruitworm, soybean podworm, and sorghum headworm) activity is starting to rise have been identified in central Maryland. The relatively mild 2020-2021 winter allowed adult moths to overwinter in Maryland, and some parts of the state experienced a higher than normal first flight in early June.

Recently planted field crops may be at risk from slug damage due to the heavy rains and cooler temperatures we have experienced in the mid-Atlantic from the end of April into the beginning of May. Therefore, the UMD fact sheet “Managing Slugs in Field Crops Using IPM Principles” may be of interest.

Agronomy News IPM Insect Scouting Tips

The Crop Protection Network (cropprotectionnetwork.com) is a national working group comprised of Extension agents and specialists from across North America that provide data through publications regarding pest management in agronomic crops. The website and publications can be a great resource for your operation. The following are the most recent fungicide efficacy tables for foliar diseases of corn and soybean.