Drought Stress is Underway
At the beginning of May, cool-season grasses in Ohio were in full swing. As June begins, some of those same grasses are slowing down due to drought stress. It has been unseasonably dry in Ohio over the last month, as we have received ~2 inches less rainfall across the state compared to the 30-year normal. As a result, the U.S. Drought Monitor (droughtmonitor.unl.edu) has much of Ohio under “Abnormally Dry” conditions. Combine a deficit in precipitation and high evapotranspiration values of late (>0.25 inches/day), and drought stress is underway.
What can I do now?
If drought-stressed turf is unacceptable for you, it’s time to irrigate. Irrigating in the early morning hours will allow water to infiltrate the soil, allowing for more water available for plant uptake. Irrigating during the heat of the day is not recommended since the water is readily lost to evaporation and evening irrigation events can increase disease incidence.
If you elect to irrigate, ensure the water applied infiltrates into the soil. Many oscillating sprinklers apply water at rates above 1 inch per hour, but some Ohio soils may not be able to infiltrate more than 0.1 inch per hour. This excess irrigation will run offsite – not where it is available for plant uptake. To combat this, consider splitting irrigation across multiple cycles in the morning hours. This will take more time and effort but will be more effective at alleviating drought stress.
In addition to irrigation, adjusting your mowing practices can improve the turf’s ability to resist drought stress and prevent further damage. Since mowing is a stressor to turf, consider pausing mowing until the turf recovers from drought stress. At a minimum, raise the mowing height – this can help preserve soil moisture.
Pause Weed Control
Most herbicide labels recommend applications to actively growing weeds, as herbicides become less effective when weeds are under drought stress. Additionally, drought stressed turfgrasses are more prone to injury from herbicides, reducing the selectivity of selective herbicides.
While forecasted temperatures next week are lower than those experienced this week, low dew points will keep water losses high. According to the National Weather Service Total Weekly Forecast ET Tool, evapotranspiration through Thursday, June 8 is predicted to total at least 1.7 inches (~0.24 inches/day) in most of the state. Currently no rainfall is in sight, but cooler low temperatures next week will allow for some recovery if irrigation is applied.