- Free living nematodes (FLN) infesting crops are mostly Trichodorus spp (stubby root nematode) and Paratrichodorus spp (stubby root nematode) but with Meloidogyne spp (root knot nematode) also occurring.
- These are most prevalent in open textured soils with moisture, particularly irrigated sands.
- Populations may be unevenly distributed vertically and horizontally and distribution can change in relation to soil moisture and root growth.
- High populations may reduce yield by feeding on roots. More …
- FLN can transmit tobacco rattle virus (TRV), resulting in spraing, but not all nematodes are carriers of the virus.
- Some common weeds can maintain TRV in the field but growing barley for two or more years can reduce TRV.
- Nematode infestation can increase the risk or severity of Rhizoctonia infection.
- Populations of FLN can be assessed from soil samples taken in the same manner as those for PCN.
- Tests may be made for transmission of tobacco rattle virus by nematodes found in a sample. More …
- Control of free living nematodes during early stages of tuber development is most important to reduce the incidence of spraing.
- Suppression of FLN may be achieved by overall or in-furrow applications of appropriate nematostats.
- In experiments, control of spraing transmission is very variable and no significant differences have been shown in mean efficacy of different products.
- Full control of FLN populations cannot be expected due to the nematodes’ ability to move up and down the soil profile and out of the range of nematostats and their wide host range.
- A product currently recommended by the manufacturer for suppression of FLN and / or suppression of spraing (TRV) transmission is:
- fosthiazate (“Nemathorin”, Syngenta)
- Recommendations are being sought by the manufacturers for suppression of FLN and / or suppression of spraing (TRV) transmission by:
- fluopyram (“Velum Prime”, Bayer)
- garlic extract (“NEMguard”, Certis)
- See the manufacturers’ websites for details of product use.
- Free living nematode species can have wide host ranges and mixtures of FLN species can occur together; rotations therefore offer limited opportunities for control.
- However, fallow, weed-free fields can result in 80-90% reductions of root knot nematodes and are likely to help reduce stubby root nematode populations.
- Biofumigation may help to control FLN populations but as FLN are more mobile than are potato cyst nematodes (PCN), control of FLN may be poorer than that of PCN.
- Some Brassica cover crops are resistant to some species of FLN and may help to reduce populations but more research is needed.
For information on chemical control, see the manufacturers’ websites.
Free living nematode notes
Nematodes 2021 (Includes effects of specialised cover and brassica crops for biofumigation / trap cropping)
Cover crops in the potato rotation 2020 (Includes influence on nematode populations)
Free living nematodes 2017 (Biology of different types of FLN; spraing transmission; control options)
Nematode control updates 2012 (Potential for trap cropping and biofumigation for FLN)
Soil pest control updates 2008 (Includes effect of FLN on potato root growth)
Pest control updates 2006 (Includes free living nematodes and spraing transmission)
Spraing transmission 1996 (Transmission of tobacco rattle virus by free-living nematodes)