Fungicide use on corn is increasing because of the promise of a good return at $5 corn. For a $20 investment, you might make another $10 to $20 in profit.

But when to apply fungicides is the question. You want to apply it soon enough to protect against diseases before they infect but not too soon so that you run out of protection before the disease even arrives.

• Applying to early before tasseling (VT) can hear lead to "beer can" ear or a short stubby ear.
• Applying to early can mean that you run out of protection before disease becomes a problem forcing you to apply a second time or live with what you got.
• If you do not schedule your aerial application early enough you might not even get it applied if planes and pilots are in short supply later on.

So scheduling an application is a challenge and something each farmer will have to orchestrate on his own.

So what are application windows for 2008 as recommended by the manufacturers?

Gary Fellows, Technical Service Rep with BASF said with Headline farmers can apply at all stage of corn, but prior to tasseling, they shouldn't use an adjuvant to prevent arrested ear development.

Jim Bloomberg, Fungicide Product Development Manager with Bayer CropScience said the best timing with Stratego is VT to R2 (blister). "Farmers get 14 to 21 days of protection. We want to protect the ear leaf of corn plant upwards and diseases usually hit at tasseling or after.

Eric Tedford, Fungicide Brand Manager with Syngenta "With Quilt we recommend spraying at R1 growth stage for best results. However the label says VT or later or when disease start. We are recommending R1 because most diseases come in at R1 (silking) and this is best time to apply protection and for it to last the longest. Any earlier of an application and farmers are spending money before disease hits. And there will be greater physiological benefits when applied at R1 along with disease protection."

So these are the company recommendations. But your goal is to maximize protection. If you apply at VT and disease hits at blister or R2, you have just given up two weeks of control for nothing and you will only have about 1 week of control after R2. Not sufficient.

Knowing how soon to apply fungicides is a quandary and there is no easy answer. If you have lots of acres to cover, spray your high risk fields first just after VT and in your low risk fields scout and wait until you see the disease on the lower leaves or until R1 or R2 before spraying. This way you can spread out your spraying and minimize your risk of loss and maximize your coverage window.