NC State Extension Publications

Symptoms

Skip to Symptoms

Nematode damage manifests itself in both above and below ground symptoms. Above ground symptoms typically include thinning, wilting or death of turfgrass. These symptoms usually occur in irregularly shaped patches that will spread outwards slowly over time if left untreated. Root-knot nematode symptoms often emulate several fungal diseases and can cause chlorotic patches in turfgrass stands.

Below ground symptoms on turfgrasses include short, stubby root systems. Dark lesions on roots are characteristic of nematode feeding damage, particularly near the root tips. Damage typically occurs at the root tips resulting in a blunted root system and the absence of feeder roots. Root-knot nematodes cause galling on turf similar to other crops, although the galls are smaller and can be difficult to identify properly without the aid of magnification, i.e. hand lens, dissecting microcope, etc.

Development Factors

Skip to Development Factors

Sting nematodes start feeding when soil temperatures in the spring are between 50-60F. Symptoms typically develop early to mid-summer due to damage from feeding in the spring months. Populations of root-knot nematode increase in late-April to early-May and remain elevated through the summer months. Lance nematode population dynamics are unknown.

Nematodes will continue to feed throughout the spring, summer and fall. Feeding and reproduction is most prevalent in the spring, but root-knot nematode still actively reproduces through the summer. Root-knot nematode produces numerous generations that may require more than 1-2 applications to be effective. Nematode activity subsides as temperatures rise above 90F. Nematode feeding can predispose turfgrass plants to Pythium root rot (Pythium spp.) and other root diseases due to a compromised root system.

Cultural Control

Skip to Cultural Control

The use of cultural control methods to reduce stress on turfgrasses is very important, particularly during the summer months. Methods are unlikely to reduce nematode population numbers, however they may help turfgrasses tolerate feeding damage. Most cultural practices for nematode feeding pressure aim at increasing the root system.

Watering: Deep, infrequent watering is recommended during the entire year. This encourages the plant to produce deep, robust rooting systems. Deeper roots reduce drought stress and the impact of nematode damage in the summer. Supplemental irrigation during prolonged drought/heat stress periods is also effective in helping the grass to avoid wilting.

Fertilization: Nitrogen fertility is very important for turfgrasses stressed by nematode feeding. Light and frequent nitrogen applications increase root growth and are beneficial during stressful summer periods when damaged root systems struggle with nutrition uptake to maintain health. Increased fertility may cause nematode populations to rise as there is more root tissue to feed on. Ultimately, improvements in turfgrass quality should be valued more than nematode population numbers.

Mowing Height: Increased mowing heights are recommended during summer months. This allows the plant to produce more energy and help counter nematode damage to root systems. For golf course putting greens, alternating mowing and rolling is a great way to alleviate stress from just daily mowing.

Aeration: Regular aeration is necessary for a healthy root system. Aerification creates more pore space for roots to grow in and increases oxygen availability to the roots. Therefore, turfgrasses can counter root loss to nematode feeding by optimizing the rhizosphere for root growth via regular aerification.

Shade: Reducing shade can help turfgrasses survive nematode feeding by providing adequate sunlight. Increasing sunlight duration produces more energy to tolerate nematode feeding.

Chemical Control

Skip to Chemical Control

Chemical control may be required to manage nematode populations in order to reduce their impact on turfgrasses. New nematicides are safer for both human and environmental health than past nematicides, but they still must be applied with care. The long-time standard, Nemacur (fenamiphos), was been banned from all use in October 2017. For that reason, it is not included below.

Application of nematicides is recommended from March-June. Applications shouldn’t be made until soil temperatures in the spring are consistently above 50-60F for sting nematode. In our research, 1-2 well timed applications are sufficient for sting nematode management. Root-knot nematode, however, produces numerous generations that may require more than 1-2 applications to be effective. Applications in mid- to late summer are likely ineffective as the root damage was done in the spring months and populations are deeper in the soil profile than nematicides can reach. Some products, such as Indemnify (fluopyram), have a long residual and may be effective if applied in the early fall.

All nematicide applications must be irrigated in immediately after application with 1/8 to 1/4" of water to be most effective. Furthermore, our research has shown that applying wetting agents every 2-3 weeks enhances efficacy of nematicides.

Nematicides should be chosen for use based upon previous sampling for species as each one doesn’t control all nematodes that may be present. Multiple nematicides may be necessary in a rotation to avoid selecting for certain species and for resistance management. Proper sampling is done by taking multiple soil cores around the edge of the damaged area no deeper than 6”. Approximately 10-20 cores are necessary for a sample. Samples should be sent to the NCDA Nematode Assay Lab for identification. If sampling for maintenance purposes, sampling an entire area in a zig-zag fashion will provide a good representation of the entire area.


Nematicide and Formulation1 Amount of Formulation2 Application Interval3 Nematode Species Efficacy Rating
1,3-dichlorpropene (Curfew Soil Fumigant)* 3 to 5 gal/A Once per year all +++
Abamectin (Divanem SC)*

3.125 to 6.25 fl oz/A

6.25 to 12.2 fl oz/A

14 to 21 days

21 to 28 days

lance

root-knot

sting

++

++++

+++

fluensulfone (Nimitz Pro G) 60 to 120 lb/A 28 days

lance

root-knot

sting

?

?

?

fluopyram (Indemify SC) 8.5 to 17.1 fl oz/A 14 days

lance

root-knot

sting

+

++++

++++

1 Other trade names with the same active ingredients are labeled for use on turfgrasses and can be used according to label directions.
2 Apply nematicides according to label directions. Use lower rates for preventive and higher rates for curative applications.
3 Use shorter intervals when conditions are very favorable for nematode activity.
* Products marked with an asterisk are not labeled for home lawn use.
Efficacy Rating
++++ = excellent control when conditions are highly favorable for disease development
+++ = good control when disease pressure is high, excellent control when disease pressure is moderate
++ = good control when disease pressure is moderate, excellent control when disease pressure is low
+ = good control when disease pressure is low
? = not rated due to insufficient data

Authors

Extension Coordinator
Entomology and Plant Pathology
Associate Professor and Extension Specialist (Turfgrass Pathology)
Entomology and Plant Pathology
Graduate Research Assistant
Entomology and Plant Pathology

Find more information at the following NC State Extension websites:

Publication date: Jan. 9, 2020

N.C. Cooperative Extension prohibits discrimination and harassment regardless of age, color, disability, family and marital status, gender identity, national origin, political beliefs, race, religion, sex (including pregnancy), sexual orientation and veteran status.