The Indiana Certified Crop Adviser panel includes Steve Gauck, an agronomy manager for Beck’s, Greensburg; Jeff Nagel, agronomist for Keystone Cooperative, Lafayette; Marty Park, agronomist with Gutwein Seed Services, Rensselaer; and Dan Quinn, Purdue University Extension corn specialist, West Lafayette. 

 

Agronomists say we are losing stand to wireworms, nematodes and other pests, and to uncommon diseases like physoderma. Are any of these truly worth spending money to control? If so, how?

 

Gauck: Scouting and understanding field history can help determine if you need to worry. Pests such as wireworms and nematodes are in the soil, and you need to prepare for them before planting as there is not a rescue treatment. A strong seed treatment with fungicides, insecticides and nematicides all help get your crop off to a great start. 

 

Scouting is your most profitable action. It allows you to identify diseases or problems early and control them. Determine the economic and agronomic thresholds of issues to know if making an application will be profitable. Utilize the Purdue Corn and Soybean Field Guide to identify diseases and insects and figure the economic threshold.

 

Nagel: Belowground secondary insect pests like wireworms, seedcorn maggot and white grubs are relatively infrequent. This is likely due to insecticidal seed treatments on corn. Asiatic garden beetles on sandy soils in northern Indiana can contribute to stand loss and stunting. We really don’t have a great handle on impact of corn nematodes. We have seen situations, particularly corn-on-corn but sometimes corn after beans, where corn plants in the V3 to V6 range are stunted or slightly behind for no obvious reason. Nematode sampling revealed high levels of lance and lesion nematodes. Needle nematodes can be damaging on sandier soils. Take soil/root samples around V4 to V6 to know if nematodes are a concern.

 

Physoderma affects plants in V3 to V8 under warmer and wetter conditions. This can lead to foliar leaf symptoms and occasional node breakage. It is usually noticed later in the season, but infection takes place earlier. Hybrids vary in susceptibility. A fungicide application at V4 to V8 can prove beneficial.

 

Park: The answer depends upon your area, the seedbed and field history. Wireworm damage is rare in the area that we serve. Standard seed treatments do a decent job on this pest. Enhanced levels of insecticide are more effective. Don’t spend additional money for insecticide unless you have a history of issues. 

 

Corn nematodes are not widespread. Nematodes typically don’t affect final plant stand, but they reduce early root growth, which affects plant growth and yield potential. We see some nematode pressure in isolated areas in light sandy fields that are normally long-term corn rotations. Severity of the damage varies with weather. Plant those fields last to help reduce potential for damage. There are some nematicides and biological options available as seed treatments that can be beneficial. 

 

I would not worry too much about physoderma. It rarely causes economic damage.

 

Quinn: If there is proof of crop damage, symptomology and yield loss occurring due to these pests, then they are worth managing. However, if there is no evidence of issues or economic losses, it would not be economical to address these issues. Using proper diagnostic measures like routine crop scouting, insect baiting and soil sampling for possible nematodes can be useful. It’ll confirm if a problem is there and if the problem needs to be managed. However, wireworm, physoderma and nematode issues are often very rare for field corn production in Indiana.