Development and Evaluation of Management Alternatives for Root Knot Nematodes and Volunteer Potatoes

Development and Evaluation of Management Alternatives for Root Knot Nematodes and Volunteer Potatoes

Summary

Plant-parasitic nematodes are important pathogens of vegetable and field crops. The loss of some chemical nematicides–the primary management tool for over fifty years–due to environmental concerns and the costs of nematicide use, has focused attention on the development of alternative methods for managing plant-parasitic nematodes. Nematode-suppressive soil amendments, cover crops, and tillage were tested for their ability to reduce nematode levels in Maryland. These sustainable management practices were evaluated on-farm (natural infestation) and in micro-plots (artificially infested).

Objectives/Performance Targets

1. Determine the effectiveness of cover crops, soil amendment with poultry litter, alternative economic crops, and tillage in vegetable rotation for suppressing nematode populations.

   Quantify the relationship between volunteer potato growth and root knot nematode populations.
   Identify currently-used crop rotation and tillage practices that adversely affect the survival of volunteer potatoes.

   Evaluate mechanical means of mulching tubers left in the field during harvesting, thereby reducing the chances of volunteer growth the following season.

Accomplishments/Milestones

Fields in Maryland cropped repeatedly to vegetables have reportedly experienced significant losses due to root knot nematodes (RKN), Meloidogyne spp.. In addition, Maryland growers are expressing concern over sporadic but widespread surges of Lesion nematode populations (Pratylenchus spp.). Lesion nematodes are often found in soil assays in association with RKN, from symptomatic fields. Both RKN and Lesion nematodes are reported to have broad host ranges. An interdisciplinary team is now into the second year of a three-year grower-generated project entitled “Development and Evaluation of Management Alternatives for Root Knot Nematodes and Volunteer Potatoes.” Cooperators on the project include specialists in field crops, entomology, nematology and vegetable pathology, along with the Dorchester County Extension Agent, IPM Scout, and Dorchester County Growers. In this project, using a combination of on-farm (natural infestations) and micro-plot (artificially infested) experiments, sustainable management alternatives and their effect on the plant-parasitic nematode populations are being evaluated. We evaluated crop rotations that use non-host crops, an organic soil amendment, tillage, winter cover crops, and double-crop soybeans in a production field using strip plots and in microplots.

Preliminary analysis has indicated that the effect of some nematode-suppressive cover crop treatments on Meloidogyne incognita juveniles (J2’s) was detected in the year following the use of the cover crop. Populations of M. incognita J2’s were significantly lower following a susceptible cucumber crop, in plots that had been cropped to sudan grass in the previous year than in plots where susceptible soybeans were planted the previous year. In addition, soybean biomass in the fall was higher in plots that had been planted with sudan grass (three of five treatments) or castor bean.

Lesion nematode populations were also decreased following a crop of sudan grass cv. “Green Grazer V” or grain sorghum cv. “NKKS 585.” Following a potato crop planted in the subsequent spring, the reduction in lesion nematodes was still apparent for two of five sudan grass treatments and the grain sorghum treatment. Following a summer crop of susceptible soybean cv. “Pioneer 94B01,” no reduction in lesion nematode levels were observed (ie. there was no apparent residual effect of the previous year’s cover crop). However, the soybean biomass was greater in three of the five treatments where sundan grass had been planted previously, as well as in treatments where grain sorghum was planted.

Additional analysis on nematode populations, crop biomass and root knot indices are being conducted.

Impacts and Contributions/Outcomes

Growers that participated in the project, at least twenty of whom helped devise research plot treatments, have begun to change their production practices. One grower recently reported “It’s learning in progress, but we’re still experimenting with cover crops. We’ve noticed a difference in the nematode populations – not 100 percent reduction, but we’re getting there.” Results are being disseminated to farmers.

Collaborators: