The 2018 season has been very odd to say the least. The unusually cold April followed by a recorded setting May had caused set backs when it comes to growing healthy cool-season turf. Jumping from temps in the mid 40s to highs in the 80s is not ideal when trying to bulk up the cool-season turf for the summer. This is also the reason we are seeing more crabgrass and nutsedge around the course than years past. For the most part, the crabgrass control held up well. A few areas had some break through but nothing alarming. Nutsedge has been more prevalent this season. Pre-emergent herbicide is applied for crabgrass and has worked well considering the type of season we are having. Unfortunately, these pre-emergent herbicides do not prevent sedges, or yellow nutsedge, which we are seeing in the rough.
The following excerpt is from a news letter sent out this past week by the Ohio Turfgrass Foundation. The author of this letter is Dr. David Gardner from The Ohio State University. This will help further explain the odd season we have been dealing with.
Much of what we are observing with weed control issues this year may be attributable to the weather patterns we have observed this growing season. April was the coolest of the last 25 years in Columbus, with an average monthly temperature of 47.7 degrees. By comparison, this is cooler than the months of March 2012 and March 2016. Because of this unusually cool weather to start the season, cool season turfgrasses, such as Kentucky bluegrass, did not have favorable conditions in which to begin growing.
On May 1 the high temperature in Columbus was 81 degrees. What then followed was the warmest May on record. The average temperature was 71.5 degrees, 9.1 degrees above normal. In 5 years since the turn of the century, the month of June has been cooler than what we observed in the month of May.
In a typical year cool season turfgrass has the months of April and May to break from winter dormancy and begin growing. The denser the turf, the fewer problems we tend to have with annual weeds such as crabgrass because dense turf shades the soil so weed seeds are not as likely to germinate. Denser turf is also more competitive with crabgrass seedlings. Crabgrass typically germinates in April but does not really begin growing aggressively until the second week of June. In 2018 we had less than ideal conditions for cool season turfgrass growth in April followed immediately by conditions that were more favorable to crabgrass and other warm season grasses. Additionally, precipitation has been at or above normal and very timely.
Because of the extended warm and wet conditions, preemergence herbicides that would normally provide near season long control likely began to break down before crabgrass stopped germinating in July. This combined with the less than competitive cool season grasses at the start of May and an extended season favoring warm season grass germination and growth has resulted in the crabgrass problems we are seeing now.
On a related note, this has been an exceptional year for sedges. They are perennial species that are favored by warm and wet conditions. Again because of the weather we have observed and the lack of cool season grass competition, nutsedge has been more prevalent this year.
- written by Dave Gardner, Ph. D., The Ohio State University
Overall, the course has been through a lot but has held up nicely. We are actively spraying post-emergent herbicide for the nutsedge and have seen a decline so far. I believe the course is in great shape and will only get better with the favorable fall season coming.
Enjoy these last few weeks of summer! Greens Aerification is next week, September 4th!