Over the 2024-2025 wheat growing season we conducted an on-farm trial in Anderson county evaluating the efficacy and return on investment (ROI) of applying fungicides to wheat. We compared 3 treatments; 1 fungicide spray at flowering, 2 fungicide sprays with one at green up and one at flowering, and an untreated check. A 40 acre field was split into strips that matched the sprayer swath of 100ft wide. Each of the 3 treatments were randomly replicated 3 times resulting in 9 strips. At harvest, the center 60ft of each strip was harvested and the grain was weighed/sampled from each strip.
Fungicides Used & Cost:
At green up the farmer applied a tank mix of propiconazole & azoxystrobin. Basically we made our own Quilt Xcel. This chemical cost $9.87/acre and we assumed an operation cost of $5/acre for the sprayer, fuel, labor etc. The total cost was $14.87/acre.
At flowering the farmer applied Prosaro Pro at a cost of $16.03/ac and we assumed an operation cost of $5/acre for the sprayer, fuel, labor etc. The total cost was $21.03/acre.
Disease & Environmental Pressures:
I scouted the field multiple times during the season. Disease pressure was considered less than normal for much of the state in the 24-25 season and that was true with this field as well. Around jointing I saw light powdery mildew in the untreated strips. During grain fill the untreated strips had light leaf rust and septoria leaf spot infections. In a normal situation, considering how close it was to maturity, I would not have recommended a spray. In the strips that were sprayed once at flowering I was able to find a few single rust pustules but I had to search for them. In the strips that were sprayed twice I couldn’t find any evidence of disease.
Harvest was delayed by a couple weeks due to repeated rains. Driving by the field you could see the difference in color between the untreated and sprayed strips. The untreated strips had a brown tint to them and the sprayed strips kept that golden harvest color. Straw quality was not evaluated in this study but, if that market is available to a farmer, the sprayed strips appeared to maintain a healthier appearance.
Results:
First, our data showed that both sprays of fungicides were profitable. Second, the largest return on investment was from a single fungicide application at flowering. Third, fungicide application appeared to benefit test weight. Our results were consistent with other research done on this topic in other parts of the country however there were no statistically significant differences in this trial.
Discussion:
While this trial makes spraying a fungicide seem like a no brainer, please keep in mind that this was in one field for one growing season. You cannot assume these results will be duplicated in your field. The takeaway from this trial should be that spraying a fungicide at flowering will give you the best chance of a positive ROI.
Please contact Alex Coleman, Small Grain & Sorghum Specialist, (864)992-5988 or amcolem@clemson.edu for further information or any questions.
