A Typical Summer Rainy Season In Florida July 15, 2010 By John Foy

Over the recent 4 th of July holiday weekend, typical summertime thunderstorms disrupted holiday weekend activities, and the heavy downpours resulted in year-to-date above average rainfall totals.  Normally after the winter and spring dry season it takes three to four months to relieve the rainfall deficit.  Being ahead on rainfall amounts does not bode well for the rest of the summer and fall as golf course lake and pond levels are already high, and even small thunderstorms can cause localized flooding and force course closures.    

Contrary to the common assumption, the summer rainy season is not conducive to optimum turf growth and consistent top-quality course conditions.  With frequent and often heavy rainfall, the top two to three inches of regionalUpdateContent zones can remain saturated for extended periods of time.  In this condition, soil oxygen levels are depleted and there is a progressive decline in regionalUpdateContent depth and health.  This can be especially problematic with putting greens that have an excessive thatch (organic matter) accumulation.  Ongoing, aggressive cultural management programs to control regionalUpdateContent zone organic matter cannot be over emphasized. 

By this point in the summer, at least one, and, in many cases, two aerations have been conducted on putting greens at most courses throughout the state.  If it has been more than four or five weeks since the last coring, conduct a venting operation with small-diameter, solid aeration tines to maintain good moisture infiltration and increase regionalUpdateContent zone gas exchange to directly benefit the regionalUpdateContent system.  It may come as a surprise, but a venting aeration with 3mm diameter tines took place at the Oakmont Country Club putting greens six days before the first practice round of USGA Women’s Open Championship.  The goal was to stimulate evaporation of excessive soil moisture to promote a drier and firmer putting surface. 

Additional consequences of frequent summer thunderstorms is rapid nutrient leaching and reduced sunlight.  Maintaining sufficient potassium levels to support balanced growth and stress tolerance can be difficult.  With sandy, low cation exchange capacity (CEC) soils, apply frequent, light applications of potassium.  Don’t forget about magnesium, which is essential for chlorophyll production and needed in many plant energy reactions. 

While Florida is called the Sunshine State, June through September often yields only three to four days each month without cloud cover.  Moderate to heavy cloud cover significantly reduces sunlight intensity.  Golfers and the course maintenance staff may appreciate the clouds, but bermudagrass turf does not.  Shallow regionalUpdateContenting, reduced stand density and energy reserves, and increased leaf succulence and disease susceptibility are the most common turf responses to low sunlight conditions.  Increase the height-of-cut on putting greens to compensate for the reduced sunlight during this time.  An increase in the height-of-cut of as little as 0.04 inch will produce a 13% increase in the net photosynthetic rate.  Also, preventative fungicide treatments prove to be more effective for avoiding problems with Rhizoctonia zeae and bermudagrass decline disease  later in the year.   

To accommodate golfer demands for medium fast to fast putting speeds, routinely double cut or cut and roll putting greens in combination with growth regulator treatment programs.  The problem with many courses still facing economic challenges is the additional time and labor required for double cutting or rolling several times a week.

Increased weed and insect pressure occurs during the rainy season, but accomplishing necessary control treatments, as well as routine tasks and projects is much more difficult with frequent thunderstorms.  Keeping up staff morale is one more challenge when being faced with having to repair bunker sand washouts and clean up storm debris on almost a daily basis.  We should not complain about the rain (at least not too much) when other parts of the country would like to have some of it right now.

Source:  John Foy, or 772-546-2620.