Turf & Landscape

Plant-parasitic Nematodes and Disease Complex

Nematodes are particularly problematic in golf course putting greens. Nematodes feed on turfgrass roots and are most abundant when the turfgrass is actively growing – in the spring and fall for cool-season grasses and in the summer months for warm-season grasses. 

Disease Complex: In addition to direct damage, nematodes may also enhance turf damage by fungal pathogens. Nematode feeding may aid fungal infection and development and increase the level of damage that is caused. Soil fungal pathogens known to form disease complexes include Fusarium, Rhizoctonia and Pythium species.

Diagnosis: Nematode problems in turf are often misdiagnosed as being the result of poor cultural practices, diseases, insect damage, soil compaction, nutrient deficiencies, poor drainage, drought or other environmental stresses. To accurately diagnose a nematode problem, a soil sample must be collected from the affected area and be assayed by a nematology laboratory where trained professionals can determine if there are parasitic nematodes present at levels that could cause the observed damage.

Sampling Turfgrasses for Diagnoses

 The process of taking a soil sample for nematode assay involves collecting random sub-samples in a zigzag pattern, figure below, from the area in question similar to the procedure that would be used for a soil sample for nutrient analysis. Soil samples for nematode analysis should be taken to a depth of 4 inches – since this is where the majority of the roots are located – with 20 or more sub-samples (per acre) making up a representative sample of the area. It is important to submit separate samples of both healthy and unhealthy turf to accurately reflect the population density of the area.

Samples collected in areas with severe damage (dead turf) may not contain many nematodes, since there are few roots available for nematode feeding. Collect samples in areas bordering the damaged area and from healthy-looking areas as well as from affected areas. Sample putting greens or fairways separately because it is important to know specifically where nematode infestations are and where they are not. This information will help in implementing sanitary maintenance practices. as well as control options.

Combine the sub-samples for a particular sample as they are collected. A convenient method is to use a small bucket or other container that is easy to carry. When 20 sub-samples are collected, mix the soil thoroughly and place approximately 1 pint into a quart-sized plastic bag. Bags should be sealed to retain soil moisture and kept out of direct sunlight – placing samples into a small insulated cooler (without ice) is a safe and convenient method for protecting the sample until it can be sent to the Nematology laboratory. Label each sample on the outside of the plastic bag with your name, address, putting green number (or other short sample identifier) and date of collecting. Ziploc storage bags are ideal for this use. You may also contact AGNEMA to request laboratory standard soil/plant collection sampling bags.

Deliver the sample to the lab as soon after it is collected as possible. If samples must be stored for a few days (up to one week), keep them in an insulated cooler at cool (air conditioned) room temperature. Do not store them on ice in the insulated cooler. You need to complete a Sampling Submission Form which must accompany your sample.

Plant-parasitic Nematode Testing

Testing soil-borne Fungal and Bacterial diseases (DNA genetic testing & analysis)

Fusarium Blight  -  Fusarium spp.

Pythium blight - Cottony blight  -  Pythium spp.

Brown Patch  -  Rhizoctonia spp.

Dollar Spot  -  Sclerotinia spp.

Take-all patch - Bermuda decline  -  Gaeumannomyces graminis

Anthracnose of turfgrass  -  Colletotrichum cereale

Bacterial Wilt  -  Xanthomonas campestris