Treating corn rootworm with nutrition

In Spring 2013 an organic grain crop grower in central Pennsylvania called, very concerned about corn rootworm in his organic corn crop. About 15%-18% of the seedlings  were noticeably delayed behind the other plants, and the rootworm larvae were spreading to the larger plants as well.

At this point, we had less experience managing insects with nutritional applications than we do today, and I was uncertain how much of a difference a nutritional application would make.

With the caveat that I don’t have experience with this situation, and I am unsure if the recommendation will work, I suggested a foliar application of AEA products that contained magnesium, sulfur, boron, cobalt, molybdenum, seaweed, humic substances, crab shell,  shrimp shell, and some other goodies.

The intent of the foliar was to rapidly convert all the existing free amino acids, nitrates, and ammonium which might be present in the plant sap into peptides and complete proteins. An additional goal was to trigger an immune response within the plant through the induced systemic resistance (ISR) pathway so the plant produces higher levels of phytoalexins which can disrupt the digestive system of the insects and shut them down.

The grower applied double our recommended rates. (You don’t know any farmers that have ever done that, right??)

Forty eight hours after the application, scouting showed that all the rootworm larvae were dead.

The crop went on to produce a full yield of 230+ bushels.

Since then, we have experienced similar success on many different types of insects in different crops. It is possible to not only prevent insect damage, but healthy plants will actually kill insects that persist feeding on them.

What I find particularly interesting in this example is that the insect was below ground, and could not have been directly exposed to the foliar application. This is a certain indicator that the plants nutritional profile was changed as a result of the foliar application, which produced the resistance response we were looking for.