Purdue Field Crop Quick Disease Guide

If the farm saw severe tar spot.
1. Watch the tracking map to know when the disease is first active in Indiana. (https://indianafieldcroppathology.com/ )
2. Download the Tarspotter app to help with determining if the weather conditions are favorable for tar spot to develop in your fields. (https://ipcm.wisc.edu/apps/tarspotter/)
3. Scout, scout, and continue to scout your fields.
4. Make informed fungicide decisions. Only in 2021 did our research trials show a benefit of two application at V10/V14 with a follow up application 3 weeks later. We have seen severe disease every season in Porter County, except in 2022
– yield impact will all depend on when the disease starts. In 2019 and 2020, we DID NOT see a benefit of a second fungicide application, that is why it is important to monitor and scout.
5. As for a fungicide timing window VT-R2 has consistently provided good protection with a single application program.
6. We need to make an informed decision on our fungicide use not only for ROI, but also for fungicide stewardship to make sure we aren’t increasing risk for fungicide resistance to develop.
7. No, it will not be cost effective to apply fungicide every year. I suggest being flexible and it is important to understand how severe the disease was on your farm. The environmental conditions play a significant role in how fast tar spot develops.

Quick Guide on Tar spot 2023

Tar spot

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