Have you noticed your home course’s turf suffering a bit more in 2018 than in previous years? If you haven’t, you are one of the lucky ones. Dr. Adam Thoms of Iowa State explains why this has been an especially difficult year for our playing surfaces in Iowa.
SPECIAL REPORT FROM DR. ADAM THOMS, Ph.D. Iowa State University
What a year for turfgrass in Iowa.
Has the turfgrass on your local golf course been on your mind this summer? We have had one of the hardest growing seasons for turfgrass so far this season. As the Turfgrass Extension Specialist for Iowa, I have had more calls and emails about turfgrass this year than in my previous time combined.
This spring we had one of the coldest April’s on record. In parts of the state we had snow cover for the majority of the month. The low temperature’s also slowed the creeping bentgrass from breaking winter dormancy. The delayed start for the creeping bentgrass allowed annual bluegrass to get an early competitive advantage in growth. Less than 30 days after the last snow melt we had 90 degree temperatures with high humidity. Typically in the spring turfgrass will spend a lot of energy both growing above ground tissue and below ground roots. Due to the low April temperatures the roots did not develop as well as they have should have, making the early high temperatures extra hard on the golf course.
Moisture was also very prevalent in May and early June for parts of the state. The regular soaking of the golf courses also kept the roots more shallow than traditionally we like to see them. During a dry spring a superintendent can push the roots deeper by watering deeply and infrequently, however when it rains regularly the roots do not need to go deep into the soil in search of water. Many courses saw large rains, which added to the monthly totals but had much of the rain run off rather than infiltrate into the soil. Those golf courses that saw flooding also saw 90 degree temperatures, which caused a loss of oxygen in the rootzone killing the turfgrass and leaving a layer of silt in the soil. The excessive amount of water in May and June also has created perfect conditions for crabgrass, and in many cases it has caused preemergent herbicides for crabgrass to fail. Due to wet conditions some superintendents have also missed fertility applications, leaving weak turf until those applications could be made.
July so far has been very dry for much of the state, with many of the days above average. With the shallow turfgrass roots drought showed up very quickly. The annual bluegrass (Poa annua) also had more shallow roots than normal, and the low moisture and high temperature stress of early July caused much damage to these plants as well. High humidity was also present for much of June and July, this added disease pressure for extended periods adding to the already stressed turfgrass, which we typically only see for a few days at a time.
This also shows the importance of having sound resources for golf course superintendent’s to utilize during growing seasons like this one. Iowa State University Extension is a great resource, which provides a Turfgrass Specialist to help with diagnosing and troubleshooting problems. Another very helpful resource is the Iowa Golf Course Superintendents Association, this network of superintendents can provide resources and support to help during stressful growing seasons and continuing education for the superintendents. The good news is that cooler temperatures were here for a few days, and fall is on its way with recovery for most cool-season turfgrasses. Finally, keep in mind that damage is done, and it will take some time and better growing conditions to recover.
Adam Thoms, Ph.D.
Iowa State University