Fair has arrived, so have corn concerns

Tony Nye - OSU Extension

Can you believe it? The Clinton County Fair is here.

If you get a chance, come visit the fair. The heat is supposed to give us a break so it should be an enjoyable week.

It is always amazing how many livestock- and farm-related exhibits come to the fair. For the 4-H or FFA member exhibiting at the fair, it will be a time for the “Thrill of victory and the agony of defeat.”

Competition for various awards will be awarded for everything from cooking and sewing to livestock and crop project judging. The excitement will be high and intense.

I hope all families involved in the fair realize it is not all about winning the blue ribbon and trophy, but learning, having fun and being a good sport. The winning is that extra “icing on the cake.”

Good luck and we will see you all at the fair!

Scouting corn fields

If you’re not at the fair, there is plenty to be doing on the farm. One thing is to scout your corn fields for disease.

I have gotten an alert this week that we are finding Grey Leaf Spot and Northern Corn Leaf Blight in the area. Now that corn is tasseling and pollinating, getting fungicides applied at the proper time and the proper rate will be critical.

Pierce Paul. OSU plant pathologist, notes foliar diseases, especially Gray Leaf Spot (GLS), are beginning to show up in some corn fields. This is not at all surprising, given that the crop was planted relatively late and it has been wet and humid in some areas.

GLS is favored by humid conditions, particularly if temperatures are between 70° and 90° F.

Foliar diseases of corn are generally a concern when they develop early and progress up the plant before grain fill is complete. This is especially true when the hybrid is susceptible. In most years, GLS and Northern Corn Leaf Blight (NCLB) usually develop late or remain restricted to the lower leaves.

However, if it continues to rain and stays humid, this will likely not be the case this year.

Due to wide variations in planting dates, weather conditions, and hybrid maturities, the corn crop is at growth stages ranging from mid vegetative to tassel across the state.

Now is the time to start scouting those early-planted fields for foliar diseases, especially those planted with susceptible hybrids in an area with a history of foliar diseases or in a continuous-corn, no-till fields. Those are the fields most likely to benefit from a fungicide application.

Use hybrid susceptibility, weather conditions, field history, and current disease level as guides when making a decision to apply a fungicide.

Based on years of research, Paul and others have found that applications made at silking (R1) or tasseling (VT) are the most effective in terms of foliar disease control and yield response in Ohio. Although they have seen a yield response to treatments applied between V4 and V10 in some years, the average yield increase is often low and highly variable when fungicides are applied before VT/R1.

Similarly, on average, the yield response is much lower and more variable when fungicides are used under low disease pressure or in the absence of foliar diseases, than when disease is present.

There are several very good fungicides to choose from. Follow the labels and keep your eyes on the fungicide price and application cost when making a decision.

When scouting keep these tips in mind when making fungicide application decisions:

• Susceptible hybrids: If disease symptoms are present on the third leaf below the ear or higher on 50% of the plants examined, a fungicide is recommended.

• Intermediate hybrids: If disease symptoms are present on the third leaf below the ear or higher on 50% of the plants examined, AND the field is in an area with a history of foliar disease problems, the previous crop was corn, and there is 35% or more surface residue, and the weather is warm and humid through July and August, a fungicide is recommended.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 30 years, currently serving Clinton County and the Miami Valley EERA.


Tony Nye

OSU Extension