Nematode Management in Florida Lawns
How to Diagnose and Control Nematode Populations in Turf Grasses
Jul 29, 2009
Nematodes are microscopic roundworms found in the sandy and loam soils of Florida and similar climates. While many nematodes are beneficial, plant-parasitic nematodes can damage and even destroy lawns and gardens. While there is not a lot the Florida homeowner can do to control these destructive pests, some preventive and management measures do exist to protect gardens and lawns from devastating nematode damage.
Types of Nematodes
The most common types of nematodes causing damage to lawn grasses in Florida are the sting, awl, stubby-root, sheath, sheathoid, ring, root-knot, and lance nematodes. Most turfgrasses are susceptible to nematode damage, including St. Augustine, Bermuda, Zoysia, Seashore Paspalum, and Centipede. Bahia grass is the only Florida turfgrass that has been shown to be resistant to nematode infestations.
Signs of Nematode Damage in Lawns
Many lawns will be able to tolerate a certain amount of nematode activity without showing outward stress. However, when the grass is experiencing additional stressful conditions, such as drought or excessive heat, it may not be able to compensate.
Symptoms of nematode problems may include yellowing, browning, thinning out, wilting or death of the grass. As grass thins out, opportunistic weeds such as sedges may begin to appear in the thinning areas. Nematode damage often appears as irregular patches of declining grass that may enlarge over time. However, many different lawn problems can cause these symptoms as well (i.e. insects, fungi, poor irrigation, or soil conditions).
The only way to be sure a declining lawn is due to nematodes is to have a soil sample tested by the University of Florida. Special care must be taken when collecting the sample, so be certain to follow the University’s recommendations or contact a local University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) County Extension Office for more information.
Pesticides for Controlling Nematodes
Unfortunately, there are no safe chemical pesticides approved for residential home use in managing nematode populations. Commercial entities may use nematicides, but due to the toxicity of these agents, they are not permitted for use on home lawns. While there are some non-toxic products on the market claiming to suppress nematode populations, the University of Florida has not found them to produce satisfactory results.
Preventive Measures for Nematode Control
The best way to manage nematode populations in the home lawn is by maintaining healthy turfgrass through proper watering and fertilization. Be warned that over-fertilizing can exacerbate the problem as it promotes the succulent new growth that nematodes (as well as insect pests) seek out. Additionally, mowing grass at a moderate height rather than cutting it too low can help keep lawns healthy and therefore improve their nematode tolerance.
If turfgrass needs to be replaced, homeowners may wish to choose a more nematode-resistant variety. Currently, Bahia grass is the most tolerant cultivar with regards to these pests. Centipede grass appears to be the only type of Florida turfgrass susceptible to ring nematodes; therefore if the grass is to be replaced due to ring nematode damage, choosing a different type of grass is recommended.
If nematodes are damaging vegetable gardens, there are additional techniques such as soil solarization that can be used to combat this nuisance.
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