Rains Continue To Bring More Challenges
By Todd Lowe, senior agronomist, Florida RegionJuly 19, 2012
|Fairy rings (left) and nematodes (right) have been common pests on Florida golf courses lately.|
July continues to be a wet month throughout many regions in Florida. As mentioned in the previous update, Tropical Storm Debby hit in early July drenching many golf courses and raising the water table. Repeated afternoon showers have kept many golf courses in our region nearly completely saturated, bringing a unique set of challenges.
Scheduling herbicide applications for controlling turfgrass weeds amongst continual rainfall is nearly impossible. Many herbicides require at least an hour to dry and absorb through the leaf surface for effective control, and predicting whether an afternoon thunderstorm will hit any particular area is a crap shoot. As a result, weeds have seemingly shot up out of the ground overnight on many golf courses, with the main culprits being sedges, tropical signalgrass and goosegrass. There are a variety of selective post-emergence herbicides for managing sedges, but limited controls for goosegrass and even fewer options for tropical signalgrass. The inevitable loss of the herbicide MSMA will create even more challenges for golf course superintendents in the future.
Evidence of fairy rings and nematodes has also been observed on visits over the past few weeks. Nematodes are microscopic plant-parasitic worms that feed on turfgrass roots. Nematode feeding causes irregular patches of chlorotic (yellow) turf with shortened roots. There are a several chemicals that can be applied to reduce nematode activity but most only offer short-term suppression. It is just as important to apply water and fertilizers on a “light and frequent” basis and to reduce as much as possible other turf stresses like shade, traffic and mechanical wear.
Fairy rings are caused by a certain group of fungi and are more of a nuisance pest. They cause either darker green, tan or brown rings on turf. There are several fungicides that can suppress fairy rings, but it is also important to apply wetting agents to reduce secondary symptoms of localized dry spots. Supplemental aeration practices will also improve the incorporation of wetting agents and fungicides into affected areas.
Turfgrass clippings are also a concern at this time since turf is growing at an accelerated pace. Mowing becomes difficult at times due to increased soil saturation and continual rainfall. Yet, the turf continues to grow aggressively. Scalping and excessive clippings can be a concern when areas are eventually mowed. Plant growth regulators can be applied to reduce turf growth and should be applied every three to four weeks to maintain growth regulation.
Increased cloudy weather can also negatively affect bermudagrass putting greens. Low mowing stresses turfgrass plants and reduces turf rooting. Combining these two stress factors can result in significant turf loss. During prolonged overcast conditions raising mowing heights slightly to increase photosynthesis can significantly improve turf health. This might cause a temporary reduction in putting speed but is necessary at times to keep the turf in good condition.
Source: Todd Lowe, firstname.lastname@example.org or 941-828-2625