Treated Seed Options Insects feeding at or below the soil level usually have the greatest impact

By Scott Stewart

[dropcap]N[/dropcap]o one can blame you if you are confused about seed treatments. There are options that differ by crop and seed companies. Seed treatments target three pest groups: Seedling fungal diseases, insects and nematodes. I’m a bug guy, so I will concentrate on the insecticide components. In corn, the insecticide seed treatment is often the key component. Nematodes are typically not a substantial threat to corn in most cases, and the base fungicides applied by seed corn companies are pretty robust and comparable.

During the early seedling stage, corn is not very sensitive to above ground pests because the growing point is below the soil surface. Insects feeding on the seed, roots or the stalk at or below the soil level are those that usually have the greatest impact. You can’t spray your way out of a problem. Of course, there are exceptions.

At-Planting Insecticide Treatments

Almost without exception, corn seed will come with a standard fungicide and insecticide seed treatment package. An at-planting insecticide treatment (e.g., seed treatment) is generally recommended. Poncho 250 (clothianidin) and Cruiser 250 (thiamethoxam) are the two insecticide treatments being marketed by seed companies. Both are pretty good, broad-spectrum choices but not foolproof. Neither provides meaningful protection against cutworms. Cruiser 250 will not do much for sugarcane beetles. Poncho is better, especially at the 500 rate.

Acceleron? This is an umbrella name for any one of several seed treatment packages marketed by Monsanto in corn, soybeans and cotton. On DeKalb and some other brands of corn seed, the standard Acceleron treatment includes a base fungicide package and an insecticide seed treatment (Poncho at the 250 rate). You may upgrade to Poncho/VOTiVO, which is Poncho at the 500 rate plus a biological product intended to provide protection from nematodes. Pioneer has a Poncho 1250 rate available upon request in lieu of the standard Cruiser 250 treatment, and VOTiVO comes as part of this package.

‘Top Of The Line’ Scenarios

When should you choose the “deluxe” and more expensive seed treatment options? With record corn prices, idle land is being put into production. Fields that were fallow, in pasture or in CRP programs are prime candidates for higher rates of insecticide seed treatments. They often have chronic infestations of wireworms, white grubs and other pests. If sugarcane beetles have been an issue in your area, lean toward Poncho at the 500 or 1250 rate.

It is relevant to mention Bt technologies. Some Bt corn traits or trait packages have pretty good activity on cutworms. Herculex, VT Double or Triple Pro, SmartStax and Viptera help control or suppress cutworm injury. Small cutworms probably cannot survive to cause significant injury to a corn stand. Here’s the rub. Larger cutworm larvae may already be in the field prior to planting. If so, Bt technologies may be overwhelmed because larger larvae are not nearly as susceptible to Bt toxins. Preplant vegetation management still goes a long way to preventing cutworm infestations.

The need for Bt rootworm technologies is pretty minimal in the South. However, there are isolated problems with this pest in parts of Tennessee and neighboring states, particularly if corn is grown continuously on the same fields. Corn traits that have Bt components for rootworm control provide good value where western corn rootworm occurs. You cannot use Bt rootworm traits on all your acres because of refuge guidelines. If not using Bt rootworm technology, Poncho at the 1250 rate is needed to consistently control western corn rootworm.

My best advice is to ask your seed dealer questions about seed treatments and price shop seed costs with each of the available seed treatment options. If you want something other than the base seed treatment, get your order in early.

Scott Stewart is the IPM Extension Specialist at the University of Tennessee.