What is localized dry spot?
With an unusually hot start to the late spring/summer season, localized dry spot (LDS) is showing up earlier and more vigorously than normal. LDS shows up as somewhat randomized, dry looking areas of turf. It is generally seen on sand-based greens, but can occur on other turfs that have been heavily topdressed with sand over the years. Sand-based soil has greater propensity for hydrophobic conditions, which is the main sign of LDS.
What causes localized dry spot?
The deeper cause, beyond sand-based soils, are believed to be organic acids and residue that coat the soil or sand particles. These organic compounds are not completely understood, but are the result of typical decomposition of leaf tissue, roots, fungal biomass and organic soil amendments included in the original root zone mix. These compounds tend to have a hydrophobic nature and once they have coated soil particles, lead to LDS. Combine this hydrophobicity with root growth stoppage in heat and soils that already have low moisture holding capacity, and the problem can become bad in a hurry.
How to manage localized dry spot
While there is plentiful research into the causes and potential areas that could be managed differently to delay or correct LDS, the primary management technique has been and continues to be the use of wetting agents or surfactants to allow water to re-infiltrate areas that develop hydrophobicity.
There are several different chemical groups in the wetting agent and surfactant world, but the goal of all of these products is to lower the surface tension of water so it can infiltrate the hydrophobic soil. It pays to do your homework on the types of products available in the market to determine which one will provide you with the best result. Some of the older chemistries can cause phytotoxic effects on plants, so make sure you fully understand what you’ve got before spraying it on your greens.
Unfortunately, there doesn’t exist today a ‘silver bullet’ to cure LDS. The best strategy is to incorporate existing knowledge into new construction and for existing problems, to know when it’s coming and be prepared with a wetting agent or surfactant strategy to minimize the damage and interruption in play. Be sure to know what your local extension has to say about LDS management in your specific area.