By Alyssa Collins and Paul D. Esker
Pathologists confirmed the first tar spot infection of this season on July 21, 2022, in Lancaster County.
After a few weeks of diligent scouting on the part of private and Extension agronomists, the first positively identified tar spot lesions of 2022 were discovered today in Lancaster County, Pennsylvania. This find indicates that environmental conditions have been sufficient for initial infections in this area, and growers should be sure to start or keep scouting on their own farms. Fields that are most likely to show infection first are those that also had tar spot in 2021 or 2020 and have high residue levels from no tillage or continuous corn production. In these fields, the spots would likely show up on the lower leaves first. In areas that have not been previously infected by tar spot, scouting should focus on the upper canopy to detect initial infections from spores that may blow in from other locations.
For information on the identification of tar spot, please visit our most recent article . More details about tar spot and its causal agent can be found in this publication from the Crop Protection Network and regularly checking the Corn ipmPIPE to see where the latest positive finds were observed. If warranted for tar spot, fungicide recommendations can be found in the updated "Fungicide efficacy for control of corn diseases."
If you spot the spots, let us know by submitting your find through our reporting system! These reports help us improve our recommendations to farmers across Pennsylvania and the region. If you are unsure about the diagnosis, contact your nearest Extension Educator for help identifying the disease. You can also alert state specialists Alyssa Collins and Paul Esker about the potential positive finds.
Source : psu.edu