Sometimes Luck Helps!

No signs of rootworm in high-yield field.

Published on: Jan 14, 2008

Rather be lucky than good? Well, that might be stretching it. Those who are good at what they do often make their own luck. But even those who do good work sometimes make mistakes. And when they do luck doesn’t hurt.

Most agronomists recommend using a soil-applied insecticide when corn follows corn, especially in parts of the Midwest. The Corn Illustrated high yield plots in ’07, located in Edinburgh, Indiana, about 30 miles south of Indianapolis, are further south than the band where rootworms often lay eggs in soybeans and invade first-year corn, Purdue University entomologists note. But they recommend insecticides for corn after corn anywhere in the state.

That doesn’t mean rootworms will always attack if no insecticide is applied. But it does mean the odds are fairly high that at least some rootworm feeding and subsequent yield damage could show up in corn after corn. Since the high-yield field was in seed corn in ’06, Dave Nanda, Corn Illustrated consultant and a long-time plant breeder, insisted that insecticide be applied.

No one argued. The farmer cooperator bought the insecticide just for that field. Since he usually plants corn after soybeans, he typically doesn’t apply a soil insecticide. As noted, the western corn rootworm variant capable of showing up in big numbers in first year corn fields hasn’t made a grand debut in his area yet.

Sometimes the best –laid plans go awry. In the heat of ‘battle’- trying to get the corn planted as early as possible- on May 1, the crew put seed in the boxes- three different hybrids. They changed seeding populations as required by the plot plan. But it wasn’t until several hours after the planter left the field that the farmer suddenly remembered that those bags of soil insecticide were still setting in his toolshed!

To make matters more risky, the three hybrids didn’t carry transgenic Bt traits- not one of them! And rescue treatments for corn rootworm are difficult and ‘iffy’ at best. The dice were rolled, like it or not- it was time to ride it out.

The farmer was almost afraid to look- he could almost see the corn falling over. But it never did! The stand was good, and except in weather-stressed, non-irrigated plots, there was little lodging at harvest. Root digs in mid-June showed virtually nothing. After digging up a dozen or so plants, washing roots and shaking soil over black plastic, he found one small rootworm larva.

Yield on the full-season irrigated part of the plot reached as high as 243 bushels per acre. There never were signs of rootworm damage.

High yield plots are already in the works again for ’08 as part fo the continuing Farm Progress Corn Illustrated project. Will the consultant recommend soil insecticide if the plot winds up on corn after corn? You bet? Will the farmer forget it this time? Not a chance! His explanation is simple: why tempt fate?