NEIAAG - 10/17/2025 20:05



Just my two cents worth but I think you are overthinking it. I have been planning on two passes since the first time I did it back in 2019. Some years, its not worth doing. Most years it is. So my concern is if you do a timing test, you likely found the best scenario for that year. Next year, tar spot comes in late, or southern rust shows up early and the "ideal" application timing is different that year. My suggestion is that since we don't have a crystal ball, go with what statistically is proven the best timing for your area, and plan on the second but be flexible. If you experience the heavy pressure we saw this year, 21 days is too late for the second and 14 days was better. But if is a dry year, low humidity and low disease pressure, you might decide at 21 days to see what it looks like at 28 days - then maybe decide to scrap the second all together. The last two years, we did not spray the second pass even though it was planned. There wasn't enough disease pressure to justify it and there were other more yield limiting factors.

All that said, we combined some corn today (October 17) that was still averaging 28 pct. and it looked like it was ready for the silage pit. So definitely if you want to overlap the generics, it will keep the plant alive.

Take care