Nematodes are microscopic wormlike animals that live in soil, roots and water. Though most nematodes are beneficial, some species can injure plants.
Nematode species that are known to infest turfgrass in Louisiana:
It is difficult to identify nematode injury in turfgrass because nematodes feed underground. However, symptoms such as turfgrass spotting can be observed above ground. The adjacent table specifies which nematode species are commonly found in bermudagrass, centipedegrass, St. Augustinegrass and zoysia turfgrasses. Spiral nematodes are commonly found in all turfgrasses but seldom cause injury if the turfgrass is well maintained.
|Turfgrass Species||Nematode Species|
|Bermudagrass||Lance, ring and root-knot|
|Centipedegrass||Sting, stubby, lance and ring|
|St. Augustinegrass||Stubby, lance and ring|
|Zoysia||Stubby, lance and ring|
Swollen root tips from root-knot nematodes.
Spotty nematode injury in turfgrass.
Injury can be observed any time of the year, but nematode populations and injury will fluctuate during the winter months and the growing season and in varying environmental conditions. During severe periods of stress that can weaken the turfgrass, nematode injury will be more severe. Injury is greatest when large numbers of nematodes survive the winter and early spring, which results in root injury early in the year. Symptoms of injury tend to show up in the same locations each year as:
One way to reduce nematode injury and accelerate turfgrass recovery is to maintain a healthy lawn through proper fertilization and irrigation and regular mowing. Never apply more than 1 pound of nitrogen per 1,000 square feet per application, and always follow soil test recommendations for proper fertility.
Irrigate infrequently and deeply while taking rainfall into account. Mow regularly, but never remove more than one-third of the leaf blade height at one mowing. Under stressful environments or during recovery from nematode injury, consider raising the mowing height. If thatch becomes excessive, dethatching may be necessary to improve conditions. Other practices, such as breaking up hardpans and soil aeration, can reduce turfgrass stress. Manage insects, weeds and plant pathogens before they cause extensive injury. Properly maintaining a lawn through these cultural practices promotes a dense and vigorous turfgrass and can increase tolerance to insect injury.
In addition to cultural practices, nematicide applications may be required to achieve effective nematode control. See the table below for a list of the active ingredients and product trade names labeled for use in home lawns. When using any nematicide, you must follow the manufacturer’s labeled directions. For more information regarding insecticides for turfgrass insect pests, please reference the Louisiana Insect Pest Management Guide at the LSU AgCenter website, www.lsuagcenter.com.
|Nematicide Active Ingredients|
|Bacillus firmus (Nortica)|
|fluensulfone (Nimitz Pro G)|