Nematode Infestation in the Lawn
Problem/Situation: We live in Orlando, and a year or so ago, we resodded the front of our lawn (about 17,000 square feet) with St. Augustine grass. Soon after, we hired a professional landscape company to manage the lawn. The lawn did well for a few months. Unfortunately, soon after, no matter how many chemicals we applied, the grass continued have brown patches, and weeds began to spread rapidly. Now our lawn looks pretty awful and so we had a company do a soil test and a nematode test (based on his recommendation).
The results came in, and based on the analysis, there were 1,000 nematodes within the sample they analyzed. The nematodes were of the lance and sting variety. I was informed that these were the worst types and our options are fairly limited:
* Apply chemical to kill nematodes, but the quality and efficiency of the chemical is doubtful.
* Resod the lawn with St. Augustine grass, with appropriate pre-sod chemicals applied, which will also require constant application for the lifetime of the lawn.
* Resod the lawn with another grass such as Bahia grass, which is fairly resisent to these types of nematodes.
Do we have any other options? Is there anything else we can do to stop the nematodes from spreading/killing our grass, or are we limited to costly measures, such as resodding, or continuous application of chemicals to the lawn?
Response: Plant parasitic nematodes are the most difficult pests to manage on turfgrass.
Nematodes are unsegmented roundworms, different from earthworms, flatworms, and other worms that are more easily observed. Nematodes living in soil are very small and most can only be seen with the aid of a microscope.
All of the plant-parasitic nematodes that damage turf in Florida feed on roots. As plant-parasitic nematodes feed, they damage plant root systems and reduce their ability to obtain water and nutrients from the soil. This makes the turf more susceptible to drought and other stresses. When nematode populations are high, the symptoms you describe are very evident including yellowing, wilting, browning, or thinning out. Grass will die under extreme nematode and environmental stress. Often, as the grass thins out spurge and other weeds may become prominent.
Damaged turf infested with plant-parasitic nematodes usually becomes evident when one of two things occur; 1) some other factor increases the susceptibility of the grass to nematode damage and/or 2) some factor causes nematode population densities to increase to damaging levels. Once the grass is planted, the best way to reduce the likelihood of nematode damage is to eliminate these factors as much as possible. Therefore, some of the best practices for managing nematode damage in home lawns look to avoiding other stresses on the grass. Properly irrigated and fertilized grass can often withstand higher levels of nematode infestation than grass suffering from drought or nutrient deficiencies. Organic amendments such as compost, mulch, and municipal sludge can help the grass tolerate nematode damage by improving plant health. Remember that anything that can be done to improve root health will help plants tolerate nematode damage
There are several pesticides/biopesticides recommended in the University of Florida “Nematode Management in Residential Lawns” . You should check with your landscape professional to see if they will treat your lawn to see if the nematodes can be managed before you decide to replace the lawn altogether.