After an erratic start, the summer rainy season has fully arrived in Florida. Beginning in June and continuing through July, afternoon thunderstorms have occurred on a regular basis. Golfers, as well as course maintenance staff, need to be continuously aware of the warning rumbles of thunder that precede spectacular, but often violent and dangerous lightning strikes. With most areas of the state having been plagued by a prolonged and severe drought, the rainfall produced by these afternoon thunderstorms has been desperately needed. Yet, more time and rain is needed to fully recover from the drought and to reestablish normal lake and groundwater levels.

While we should never complain about the rain, the frequent and, at times, heavy deluges do contribute to additional turf and course management challenges. In some instances, 2- to 3-inches of rain has occurred in an hour or two, and the resulting localized flooding causes setbacks in accomplishing routine management practices and requires additional time be spent on debris cleanup and repairing bunker washouts.

Additional problems commonly encountered are explosions in weeds and an increased incidence of fairy rings. At the very first signs of an outbreak of fairy rings the importance of proactive treatments with recommended fungicide and wetting agent combinations cannot be over-emphasized. Once fairy rings become fully expressed recovery tends to be a slow process.

Contrary to the common assumption, maintaining optimum putting green turf health and top quality conditioning is a very challenging proposition at this time of year. While hot temperatures are favorable to maximum sustained warm season turf growth, rapid shoot growth also negatively impacts putting speeds. Judicious nitrogen fertilization and growth regulator treatments can help, but a sustained growth rate also must be maintained throughout the summer to ensure recovery from core aeration and other cultural management practices.

Also, with frequent and at times heavy rainfall, a moisture-saturated rootzone persists. This condition results in a depletion of soil oxygen content, followed by a decline in root system health and depth. When afternoon thunderstorms do not occur for a day or two, the rapid onset of drought stress can be a problem. Thus, it is absolutely essential that close attention to supplemental irrigation during the rainy season continues to be practiced.

The daily summer forecast for the Sunshine State is hot and humid, partly cloudy, and a 50% or more chance of thunderstorms. While the skies may be clear first thing in the morning, thunderstorms begin building by mid-day and results in a dramatic reduction in cumulative solar radiation. The reduced sunlight intensity has a significant impact on bermudagrass growth. Reduced sunlight intensity can be further exacerbated on putting greens with the continued practice of very low heights of cut. Along with slightly raising heights of cut, additional care must be exercised with both the aggressiveness and frequency of other cultural management practices, such as verticutting, so that the combination of mechanical and environmental stresses does not result in a setback in turf health and coverage.

A survival management strategy is necessary through the rainy season, and everyone also needs to keep their fingers crossed that we do not get another direct hit by tropical storms or hurricanes, which would only add insult to injury.

Source: John Foy, jfoy@usga.org or 772-546-2620