Hot + Wet + Humid Weather = Disease

July 7, 2015

Joe Rimelspach- June 2, 2010

Brown patch

Lawns – In central Ohio brown patch starting to develop during the week of May 24. Samples from home lawns consisting of tall fescue and juvenile perennial ryegrass were diagnosed with brown patch. Tall fescue lawns that have the disease this early in the season may have a chronic problem if warm wet weather continues. This could be a pattern for severe thinning and deterioration on tall fescue lawns. However, if there is an extended cool and dry period, lawns may recover and perform well. Keep a close diagnostic eye on turfgrass areas that have had a history of the problem or that are located in areas prone to brown patch; over watered, shaded, wet, poor air circulation, etc….

bygl 1 6-2-10

Golf Courses - This week brown patch has demonstrated symptoms on creeping bentgrass, especially on tees and fairways. This was noted at the Ohio Turfgrass Foundation Educational & Research Facility in the last few days. If temperatures are warm, nights are humid and there are wet conditions brown patch will become prevalent. Cooler temperatures and or dry conditions will greatly slow the development of brown patch.

Pythium Blight

Golf Courses- The first case of Pythium Blight (foliar blight) was confirmed in the clinic. The outbreak occurred on May 30 and 31! This is the earliest confirmed case of Pythium Blight on an established mature stand of turfgrass that I can remember!!! My memory is not so good any more … but this is amazing for central Ohio. The site was a fairway at a local golf course. The fairway was primarily bentgrass but the diseased area was a low site that was primarily perennial ryegrass and annual bluegrass. The perennial ryegrass had that classic black greasy appearance and under the microscope was the typical Pythium aphanidermatum mycelium.

bygl 2 6-2-10

Research by the Plant Pathology Department at Ohio State University has found that Segway (cyazofamid) and Stellar (propamocarb + fluopicolide) are excellent new products to consider using along with traditional products such as Subdue (mefonxam) and Banol (propamocarb) both systemic, or traditional contact / knock down products such as chloroneb or ethazole. The strobilurins ( Heritage & Insignia) are unique since they work on both Pythium and brown patch. The phosphites are considered best if used as preventative turf health management materials. You can view the OSU “Families of Fungicides for Turfgrass” chart for more details.

Now would be a good time to review your summer disease fungicide choices and strategies if you haven't done so for this year.