Soybean spraying in Iowa in 2011
The results of this Iowa State study are about what you'd expect, but not necessarily what we do. 🙂 In other words, profilactic spraying does not pay. Spray if you need to.
The results of this experiment illustrate the benefits of foliar fungicide and insecticide applications for the management of foliar diseases and insects. There were very small amounts of foliar disease across the state of Iowa in 2011 due to high heat and low rainfall amounts in July and August. Also, this was a moderate soybean aphid year across much of the state. At the four locations with very low insect populations and disease severity, there were no significant yield responses to either insecticides or fungicides. However, at the Ames location, fungicides reduced frogeye leaf spot in the upper canopy and the largest yield responses to fungicides were at this location.
Also, only one of the six locations (Sutherland) reached the threshold level to spray aphids and this was the only location where all insecticides had significant responses to insecticides. Using foliar fungicides and insecticides is an effective way to prevent yield losses to foliar diseases and insect pests. Also, only applying pesticides when needed can reduce overall production costs and preserve product efficacy for when severe outbreaks do occur."
Re: Soybean spraying in Iowa in 2011
Just like over using antibiotics came back to bite us in the butt I foresee similar problems in the future with over using fungicides and insecticides. Already seeing reports where rootworms are becoming resistant to BT corn which has also been over used/pushed similar to how seed companies over pushed RR seed.