Tar Spot

As corn harvest winds down, 2023 planting plans are already taking shape. The end of the growing season added yet another potential variable for next growing season: Tar Spot. Found in five northeast Kansas counties (so far) for the first time this year, Tar Spot has been a disease of focus since it was first discovered back in 2015. What we’ve learned is concerning.

For starters, the disease prefers mild temperatures up to the mid 70s. Like most fungal diseases, it also likes high humidity and long periods of leaf wetness. Prolonged periods of leaf wetness are likely what resulted in it showing up here this season, and is likely to be a contributor to potential issues in irrigated corn moving forward. It also tends to survive in corn residue, with continuous corn being another potential “hot spot.”

There’s no guarantee that 2023 levels will warrant concern, but the fact the disease is here increases those chances and the need for proactive action. Start by evaluating rotations and selecting hybrids to help combat potential infections. University of Illinois studies in 2018 indicated a “significant response to Tar Spot” with hybrids in the same trial exhibiting severity ratings from two and a half to over forty percent. There is some promising work to help combat Tar Spot from the genetics side, but to date, no hybrids are known to have genetic.

Looking ahead, start thinking about irrigation timing, fungicide applications and focused scouting during the next growing season. Even slight changes to an in-season management program could help a great deal towards preventing further pressure from this disease. 

For more tips and a summary of disease findings, check out the newest KSU Agronomy eUpdate at https://webapp.agron.ksu.edu/agr_social/article_new/tar-spot-of-corn-is-now-confirmed-in-five-counties-in-kansas-516-5 or contact any District Office.

Late Lawn Seedings

The typical fall window for seeding cool season turfgrasses closes in mid-October. It’s not that later seedings can’t make it, but the odds do go way down. The reason: rooting.

We often blame the failure of late seedings on seed not germinating or young plants being sensitive to cold. That’s possible, but most of the time, the lack of an extensive root system is of greater concern. Sometimes, that lack of root system results in heaving during freeze/thaw cycles. If young plants are heaved out of the ground, they’ll typically dry out and die.

The other problem can be a lack of energy to help seedlings get going. The seed provides energy to the young seedling, but if enough top growth doesn’t occur prior to winter, root systems may lack adequate energy to help the plant survive the winter and take off next spring. 

For best results, keep newly seeded turfgrass stands watered through the fall. Mature lawns need less frequent watering but all should go into the winter with moist soil.

David Hallauer60 Posts

David Hallauer is the Meadowlark Extension District agent in the areas of horticulture and crops and soils.

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