Fungicide applications have been all the rage in the past couple of seasons, particularly with regard to the corn crop. Some have seen benefit from these applications but quite frankly most have not. Coordinated Land Grant University fungicide trials from across the Midwest in the 2007growing season, in Illinois, Iowa, Indiana, Ohio, Missouri and Kentucky have demonstrated that a foliar fungicide application between VT and R1 resulted in economic yield benefit approximately 30% of the time. What? Well, that means that 70% of the time the applications resulted in yields that were not significantly different from the untreated treatment or yielded worse than the untreated treatment. Foliar disease pressure was very low this past season all across the Midwest. For the money, assuming about $20 for product and application it would seem to be evident that health benefit from a fungicide application in the absence of disease or in a low disease environment is not being demonstrated. This data can be found at http://www.plantmanagementnetwork.org/pub/trial/fntests .

Looking more closely at the data does reveal that a difference does exist though between hybrid yields when that data is separated in to disease susceptibility classes. The first being, hybrids that have fair to poor resistance to gray leaf spot and the second being hybrids that have good to excellent resistance to gray leaf spot. For this analysis, 31 hybrids with fair to poor resistance demonstrated an economic benefit 50% of the time with an average benefit of 6 bushels compared to the check. And for 121 hybrids with good to excellent resistance an economic benefit 40% of the time with an average 3 bushel benefit compared to the check. Specifically for Illinois in an experiment looking at 72 hybrids conducted across the state by our Extension Pathologist Carl Bradley, the results mirrored the Midwestern data conclusions.

Based on these and previous years data, recommendations have been developed based on risk factors and disease observations to assist you in making a decision about whether fungicide application should be made to your corn. The risk factors to consider include the previous crop, for instance corn on corn has a higher risk of disease, than corn in soybean residue. Next the susceptibility of the hybrid needs to be considered. Then, in season, the current and predicted weather needs to be considered and finally the planting date. Late planting increases risk of losses from foliar blights. With regard to disease observations, if you have a susceptible or moderately susceptible hybrid consider fungicide if disease is present on the 3^rd leaf below ear or higher on 50% of the plants prior to tasseling. If you planted an intermediate hybrid consider fungicide if 1)the field has history of disease; 2) the previous crop was corn with at least 35% residue; and 3)disease is present on 3^rd leaf below ear or higher on 50% of plants prior to tasseling and 4) if warm and humid weather is present thru July and August. If you have a moderately resistant or resistant hybrid, fungicide is generally not recommended but you should still scout for disease development. The bottom line? We have some excellent fungicides available to us for managing disease in the corn crop. If you grow susceptible to moderately susceptible hybrids in a year that is conducive to development of leaf blight, particularly gray leaf spot, you will most probably see benefit from a timely application. Otherwise, you are not likely to benefit.

The data from several years supports these recommendations which are grounded in an integrated pest management decision making process, so what is the conundrum? Well, the reality of the situation is that many producers are being advised to lock in to a fungicide purchase and application service program by March or April. This certainly places a producer in a situation that is between a rock and a hard place. What is a consumer to do?