FAQ

I would not recommend treating the soil prior to laying new sod.  While you have experienced problems with necrotic ring spot, the organisms that cause
this disease are always present.  They only "outbreak" when the conditions are right.  What I would recommend is that you work to keep the new sod
healthy and manage it so that outbreaks of necrotic ringspot are reduced.

To that end, cultural controls recommended by our Plant Pest Diagnostic Lab include:

Cultural techniques that prevent the lawn from becoming stressed will help prevent these two diseases. In early spring or fall, the lawn should be
aerated. Aeration improves water penetration and reduces thatch, thus alleviating conditions that cause stress. Nitrogen fertilizer should be
applied frequently at low rates or in slow release forms such as sulfur coated urea or IBDU. This avoids undesirable flushes of growth which are
more susceptible to disease. Mow the lawn at a height of 2-3 inches often enough so that only 30-40% of the leaf length is removed per mowing. In most
soils, the lawn should be watered infrequently and deeply. Sandy soils will require more frequent, light irrigation. Wet the entire rot zone when
irrigating.