By Darren Hefty

There has a been a push for early fungicide applications in corn at V4 to V7 for a number of years now, and in soybeans there have been questions but little data in the early stages. Here are a few facts about fungicides you’ll need in order to understand the dynamics involved in fungicide use in any situation.

FUNGICIDE FACTS

  1. Fungicides are preventative. They must be applied before the disease hits in order to protect the maximum amount of yield.
  2. Plant health benefits are real. There actually are changes made inside plants after fungicide applications that cause the plants to respond to stresses differently. Even if you don’t have disease issues, a fungicide application can pay solid dividends.
  3. Coverage is critical. Fungicides do not move well inside the plant and can only protect the plant tissue they come in contact with. If you don’t get spray coverage on the lower leaves, they are unprotected. If a leaf or other part of the plant has yet to emerge, you can’t protect it with a fungicide application.

Keeping those things in mind, here’s a look at each crop and why you may consider a fungicide application in each crop this year.

CORN

There has been a lot of research on V4 to V7 fungicide applications in corn. The data shows there may be an average of 2 to 5 bushels to gain, but there is plenty of variation. So how do you achieve a consistent response and a good return on investment?

  1. Shoot for V6 to V7. This puts more leaves on the corn plant that you can protect. It also gets you into a time where more diseases could potentially begin striking your corn.
  2. Change spray tips. We find far too many fungicide applications being made with drift reduction nozzles, resulting in poor coverage. Use flat fans instead.
  3. Consider a reduced rate of fungicide. I know that sounds a little crazy to some, but we’re dealing with a smaller plant than we will have at tasseling time. Doesn’t it make sense that the dose required would be less? This doesn’t apply in all situations, but talk with your agronomist about whether this may be the right call for you.
  4. Combine the application with something else. If a herbicide, insecticide, or other treatment can be done at the same time, your additional application charge is $0 for the fungicide application.

SOYBEANS

On our farm (which is in a semi-arid climate), fungicide application in the R2-R3 stage is a no-brainer. We’ve seen consistent gains and a nice return on investment. We’ve also seen a big improvement in the appearance and viability of the seed produced. The questions we’ve asked ourselves and that have been asked by many growers are, “What about an earlier application, as well? The reproductive stages are one thing, but what about the vegetative stages of growth?” Based on what I’ve seen from growers across the country, here’s what I’ve observed.

  1. Higher yield goals require higher management levels. If you’re shooting for 30-40 bushel yields, early fungicide applications are not where your next dollar should be invested. If you’re shooting for 70+, the gains pay much better.
  2. Protecting lower leaves. Leaves catch the sun and convert it to energy. There are only so many days and so many leaves. I see diseases like septoria brown spot in almost every field I walk. Check your own soybean fields and question what’s going on with those lower leaves. Doesn’t it make sense to protect them if you want maximum yield? Half rates are generally sufficient on small plants.
  3. Heavy disease pressure areas and the right weather conditions. If your ground has a history of disease and/or if the weather is just right (damp and not super-hot), you have a much greater chance for a fungicide payoff. Even sudden death syndrome (SDS) that had no foliar fungicide answer now has a solution, or at least a way to suppress it post-emerge: Fortix. Fortix won’t completely control SDS, but if you are going to get SDS this summer, it should give you a yield bump. SDS doesn’t appear to show up until late in the season, but it actually begins with infection early in the year in most cases, so spraying early rather than late should be a good thing.

Yes, the market prices aren’t what they once were. However, there may be a good chance to protect your crop from stress and make more money on your farm this year with an early fungicide application in corn and/or soybeans. If you make that choice, though, commit to doing everything right to ensure the fungicide works to the fullest. Don’t just throw a fungicide in the tank and spray it out like Roundup. Fungicides are much, much different.