Localized dry spot can be a superintendent’s nightmare during the stressful summer months in the Northeast. It usually appears from mid June through early September, but can be visible earlier or later in the growing season.
The main cause of localized dry spot, or water repellent soils, is a build-up of organic acids that form on soil particles. These organic acids are made of plant exudates and fungal hyphae, such as Fairy Ring, that are made up of non-polar molecules. Water is a polar molecule, therefore it cannot attach to soil particles for uniform hydration.
These non-polar coatings are always present and are a by-product of growing a good stand of turf. Localized dry spot is present in all turf situations. They are more prevalent on golf courses due to the different heights of cut and other stresses the turf endures. These organic coatings are even present in the winter months, but because of adequate moisture available, and lack of turf stress, localized dry spots are not evident.
Wetting agents, or soil surfactants, are one of the tools available to superintendents and turf managers to combat localized dry spot. Wetting agents have both a polar and a non-polar end to the molecule and create an adhesion sight in the soil. Therefore, the non-polar end attaches to the organic coating and the polar end can then hold water to hydrate the soil.
Another obstacle with uniform water movement into the soil is thatch. Thatch is also non-polar. Water will evaporate versus penetrate into the soil during the summer heat thus making the water unavailable to the roots.
Nature Safe can be an important tool in managing localized dry spot. If used in a continuous program the natural ingredients will aid in deeper roots, disease management and thatch reduction. Nature Safe contains humus that not only affects nutrient holding capacity, but also water holding capacity.
Fall aeration is an ideal time to incorporate Nature Safe and begin the process of thatch reduction. It will establish a much deeper root system, improve soil porosity and the air and water ratios in the soil.
Nature Safe and soil surfactants are the winning combination to prevent and manage localized dry spots.
Pace Turfgrass Research Institute conducted an evaluation of fungicides and Nature Safe for control of localized dry spots and Fairy Ring. The results show that Nature Safe can successfully be used as a management tool in controlling localized dry spots and fungal invasion.