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 chemical nematicides, the primary management tool for over 50 years, has, due to environmental concerns and the costs of re-registration, 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. All nematode suppressive soil amendments and cover crops tested reduced root knot nematode (RKN) populations at harvest. Additionally, of all seasonal samplings and RKN life-stage evaluations, fall stage 2 juvenile soil sampling was the best indicator of presence and RKN population.

Objectives/Performance Targets

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 effects 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 fields using strip plots and in microplots.

Impacts and Contributions/Outcomes

Treatments for both field and microplot test sites are demonstrating similar and significant management effects. Both sites are now in process of sampling the second treatment application for the second consecutive year of testing. Statistical analyses will evaluate cropping sequences over the entire three-year time period. However, a number of individual treatments have resulted in significant reduction and suppression of numbers of M. incognita second-stage juveniles (J2) in soil in both field microplot and field demonstration trials. Susceptible vegetable crops grown in RKN infested soil sustain a significant increase (the population doubles) in final population of free-living RKN second-stage juveniles recovered in soil assay. All nematode suppressive soil amendments and crop treatments tested thus far resulted in significant declines in RKN populations sampled at harvest. Additionally, of all seasonal samplings and RKN life-stage evaluations, fall soil J2 sampling had the greatest significance as an indicator for detection and population evaluation purposes in MD.

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