Fungicides work on corn and it is not just about disease prevention. It is also about longer stay green and better standability. But is there something to this stay green effect and does it bump yield in absence of disease?

Tom Doerge, Agronomist with Pioneer Hi-Bred said "The data is very positive. I was a skeptic in the beginning. But with new chemistries on the marketing containing strobilurins, it seems to be effective when disease pressure isn't always obvious."

Eric Tedford, Fungicide Technical Brand Manager with Syngenta said "Our Quilt product controls pathogens that cause gray leaf spot, common rust, southern rust, northern corn leaf blight, northern corn leaf spot, southern corn leaf spot, and eyespot. All of these diseases are capable of nibbling away at yields. In addition, azoxystrobin, one of the active ingredients in Quilt fungicide, has beneficial effects on critical plant physiological processes that enhance plant performance."

Tedford said that azoxystrobin, Syngenta's strobilurin fungicide, has effects on physiological processes that can enhance plant performance. These include the following:

• Increases carbon dioxide assimilation and improves photosynthetic efficiency.
• Increases plants water use efficiency by reducing transpiration or water loss from the plant.
• Increases green leaf area by reducing ethylene. This slows down the senescence or aging process and loss of chlorophyll and allows plants to stay greener for longer.

"This means that plants have more time to convert the sun's energy into crop yields (plants can photosynthesize longer)," said Tedford. "We believe strongly that the foundation is disease control first and beneficial physiological effects second. We do not advocate its (Quilt) use in non disease situations."

Gary Fellows, Regional Tech Service with BASF concurs that they see the strobilurin effect. We see it but it is much harder to separate out from everything else. We see stress reduction, more growth efficiency and stay green but we can't separate out a yield bump. We say we see much better plant health."

Jim Bloomberg, Fungicide Product Development Manager with Bayer CropScience also acknowledges an additional benefit from greening that some maximizes yield potential.

So the stay green effect and better plant health is a real observation and this leads to better standability. But whether it bumps yield in absence of disease is less certain.