Regular scouting and field evaluation is a wise practice this coming growing season, according to DuPont Pioneer researchers and agronomists. Mild winter temperatures may have aided the survival of overwintering pests and diseases, which could impact crop yields if not discovered and controlled.
“Every year is a balancing act between good growth and vitality and early-season insects and pathogens,” says Scott Heuchlin, DuPont Pioneer research scientist, field pathology. “For growers who were able to start the season with a warm seedbed, good soil tilth and sunshine during emergence, the balance is shifted in favor of the plant. The biggest challenge will be for seeds that were planted into less-than-ideal seedbeds, creating stress for plants and making them vulnerable to pests and diseases.”
Pests to Scout For
“Growers should scout for the typical early- and mid-season pests this year,” says Paula Davis, DuPont Pioneer senior manager for insect and disease traits. “For corn, growers should be looking for black cutworm and corn rootworm. In soybean crops, bean leaf beetle, soybean aphids and brown marmorated stinkbugs may be a problem.”
Black cutworm – Spring storms prior to tillage and planting provided favorable conditions for this pest. Corn plants are most vulnerable up to the V4 stage and susceptible up to the V6 stage. The following practices are recommended for management: monitor flight reports, scout fields and incorporate tillage. Consider a rescue treatment if plants are small, cutworms are active and economic thresholds are exceeded. Broadcast pesticide or bait application may be used as a rescue treatment. DuPont Asana XL provides long-lasting control of labeled corn pests, including destructive cutworm.
Corn rootworm – Cool spring conditions throughout the Corn Belt have delayed expected timing of rootworm hatch. To protect corn from rootworm damage, DuPont Pioneer experts encourage multiple management strategies. During the growing season, focus on routine scouting and evaluation of trait performance. Check fields for larval corn rootworm injury to determine pressure and product efficacy. Scouting for adult corn rootworms, especially in corn-on-corn production and fields with suspected resistance, is also recommended. Estimating adult populations will help determine potential larvae density and can help inform management decisions for next season.
Overall, the most effective management strategy is to incorporate a crop rotation that alternates corn with other crops. If continuing with corn, consider a dual mode of action in corn rootworm resistant traits, especially if you’ve used the same one for several years. Optimum AcreMax Xtreme technology provides two unique modes of action for above-ground insect control, and two individual modes of action for below-ground insect control. Soil insecticide treatments are also an option to help control larvae.
Bean leaf beetle – Soybean plants are especially vulnerable up to the two-leaf stage. There is also potential for later generations of the bean leaf beetle to come in and feed directly on the pods. To manage populations, you should scout and monitor fields early. Insecticide seed treatments are generally effective in reducing damage from overwintering pests. However, you may need to spray to combat later-season threats.
Soybean aphids – While reports of soybean aphids last year were uncommon and limited to Northern states, aphid populations can rebound significantly after low years. Natural predators, such as lady beetles and insidious flower bugs, may help to suppress populations. It is a good idea to keep an eye on the pest, scouting fields from late June through August. DuPont Asana XL has proven to be a great value for soybean aphid control. Apply when populations reach threshold levels to help maximize yield. The economic threshold to justify insecticides is 250 aphids per plant. Insecticides should be applied before the R5 plant stage and populations reach 1,000 aphids per plant.
Brown marmorated stinkbugs (BMSB) – Pests continue to expand across the country, including every state east of the Mississippi and several western states. Locations near forested urban areas are at higher risk. Since the distasteful bugs have few natural enemies in North America, close scouting is essential, particularly around the field borders where bugs tend to feed. DuPont Lannate brands are available for use on selected grain crops in areas with potential for losses due to BMSB.
Diseases to Monitor
If planting was rushed and seeds were planted into cold, wet soils, there is a risk for seed rot and damping off. The best protection for the seed is fungicidal seed treatments. The Pioneer Premium Seed Treatment (PPST) includes a unique combination of fungicide, insecticide and other options to help you avoid early-season challenges. Given the late start to planting this year, seed treatments will protect seed as soil temperatures warm up quickly and allow plants to get out of the ground.
Scouting fields regularly will help to identify planting issues, such as seedlings that have not emerged or lower-than-expected population counts. Efficacy of seed treatments becomes a challenge if the seed fails to germinate due to cool, wet conditions, or saturated soils dilute the treatment. By the two-leaf stage, you should be able to determine whether there are seedling emergence issues.
To help track field notes and assist with early-season scouting, Pioneer launched the Pioneer Field360 Notes app. The tool streamlines and organizes field-by-field agronomic information for communication between DuPont Pioneer agronomists, sales professionals and growers and is compatible with all tablet and mobile devices.