Jay Capasso, UF IFAS Columbia County Extension, Zane Grabau, Entolomology and Nematology Department
Nematodes are generally microscopic worms who live in the soil or plants of our crop fields. Although there are beneficial nematodes that feed on organic matter, bacteria, fungi or other nematodes, some nematodes are parasitic to crops such as peanuts. Nematodes love Columbia County’s sandy soils and high populations of parasitic nematodes such as root-knot nematodes can be found in our crop land. Parasitic types of nematodes include ecto parasites who live in the soil feeding on plant roots and endo parasites who live much of their life cycle inside the root of the plant where they feed.
Plants damaged by parasitic nematodes contain foliar and/or below ground root symptoms. Foliar symptoms include chlorosis and stunting similar to nutrient deficiencies. These symptoms may occur in irregularly shaped patches of the field where plant parasitic nematode populations are highest. Root symptoms include galling or swelling of the roots. Galling is often mistaken for nodules where biological nitrogen fixation occurs in leguminous plants such as peanuts. Galling involves irregular swelling of the root. In comparison nodules are generally smaller, spherically shaped, easily removed from roots, and light pink or purple on the inside.
In 2019, an on-farm trial was conducted in Columbia County in a field which experienced nematode damage in peanuts the previous season. In the trial peanut variety and the use of the nematicide Velum Total (Fluopryam) were investigated. The trial compared peanut variety Georgia-06G a nematode susceptible variety commonly planted in the region to TIFNV H/O a nematode resistant variety. Replications of Georgia-06G and TIFNV H/O were planted with and without the application of Velum Total. Yield results are likely low due to in field measurement error. According to the grower the field had an average yield of 3000 lbs per acre. However, peanut yield was measured using the same methods for each treatment, so the general trend of the results is believed to be accurate (Fig 1, Table 1). Peanut variety was found to have a larger effect than the application of Velum Total on peanut yield. Nematode populations were also found to drop substantially after planting the resistant TIFNV H/O variety which may be beneficial to future crops. Yield results and images 1 and 2 demonstrate the effect of using a nematode resistant peanut variety TIFNV H/O in an infected site compared to Georgia-06G.
Nematodes will not actively migrate from field to field. However, they can be transported on farm equipment, soil, water, or plants. Cleaning farm equipment can help prevent the spread of parasitic nematodes! Common nematicides labeled for peanuts in Florida include fumigants Telone II (1,3 Dichloroprolene), Vapam HL (Metam sodium), and Kpam HL (Metam potassium) applied pre-planting. Vapam HL and Kpam HL are less commonly used than Telone II due to their cost. Non fumigant options include Velum Total, Aglogic (aldicarb), Vydate (Oxamyl), and MeloCon Wg (live bacteria). Crop rotations should also be considered when managing nematodes. Field corn rotation is good for managing the peanut root-knot nematode, the most commonly found parasitic nematode in peanuts, but not for managing other types of parasitic root-knot nematodes such as the Javanese root-knot. Cotton is a good rotation crop with peanuts for managing parasitic root-knot nematodes. Grasses such as bahiagrass and bermudagrass are also good rotation crops for managing parasitic root-knot nematodes. Other parasitic nematodes such as the sting and lesion nematodes are difficult to manage through crop rotation due to their wide host range.
|Peanut Yield (lbs/acre)
|TIFNV H/O-no nematicide
|TIFNV H/O+Velum Total