By Brian Hefty
What a year for volunteer corn! We started getting calls and emails about it in April this year before we even had corn out of the ground on our farm. With all the trait options and herbicide tolerant crops, it’s time for a refresher course on volunteer corn control.
Your Volunteer Corn is Resistant to The 2 Best Chemistries!
What?!? Yep, you read it correctly. I assume that the best chemistries are not going to work anymore. I’m referring to Roundup and Liberty. Since there is so much corn out there that is resistant to both of those products, it makes sense that the volunteer corn (even if you aren’t planting those traits) is going to have a pretty healthy percentage of plants resistant to those chemistries.
Why Should I Control Volunteer Corn?
Volunteer corn is a terrible eyesore in a soybean field. We can all agree on that. However, on a weed for weed basis it’s also the worst yield robber of any weed (Palmer pigweed included). No, it’s not going to produce a million seeds per plant like pigweed, but it is going to take up more water and nutrients while stealing more sunlight than any other weed I can think of.
The other thing that’s starting to get a little more press is the fact that corn rootworms LOVE volunteer corn. Just dig up some volunteer corn plants early to mid-season and look at the roots. They will likely be chewed up, and they may still have rootworm larvae around them. For this reason, not only do you need to kill volunteer corn, but you need to get it done early.
Timing
The one and only growing point on a corn plant stays safely below ground until about V6. For this reason, early season applications of products like Gramoxone and other contact-killers tend to just fry off the above ground leaves, much like a frost will do. However, the gramaticides like Fusilade can still be quite effective. For volunteer corn under 12” tall, a standard rate of most grass herbicides works well. Above 12”, a higher rate is required.
Ranking the volunteer corn herbicides in terms of performance, Fusilade stands out as the best. Assure II and the generic quizalofops are a close second, though. The clethodim products come in as a distant third.
Volunteer corn control is very important to your yields and profitability this year. It’s also important to your corn rootworm control for next season, as well.