Alternate Management of Leafhopper Pests in Integrated Farming Systems: Demonstration of Biological and Cultural Controls

1991 Annual Report for ANE91-005

Project Type: Research and Education
Funds awarded in 1991: $0.00
Projected End Date: 12/31/1993
Matching Non-Federal Funds: $63,750.00
ACE Funds: $62,400.00
Region: Northeast
State: Maryland
Project Leader:
Nicholas C. Maravell
Maryland Organic Food and Farming Association

Alternate Management of Leafhopper Pests in Integrated Farming Systems: Demonstration of Biological and Cultural Controls

Summary

Farmers from the Maryland Organic Food and Farming Association initiated this project to demonstrate viable leafhopper controls for three crops important to their rotations: alfalfa, vegetable beans and potatoes.

At present, the potato leafhopper, Empoasca fabae, is a major limiting factor in large scale low-input or organic plantings of these crops. Farmers avoid these crops, use high-cost control measures, or suffer unpredictable levels of damage. Because of the highly mobile nature of the insect and its reproductive capacity, its impact during a year is difficult to predict and insecticides are currently the primary control tactic. In addition, as conventional farmers adopt alternative controls for Colorado potato beetle and Mexican bean beetle, major leafhopper resurgence as a secondary pest due to disturbance and its natural enemies has been an unanticipated consequence.

New knowledge of leafhopper natural enemies and its behavior in non-host plants has yielded biological and cultural controls as effective alternatives to chemical insecticides. We are demonstrating, in the various distinct growing regions of Maryland, two such alternative controls. One is a fungal pathogen, Zoophthora radicans, which is released by an inoculative technique in response to scouting. The other is a cultural control in which non-host grasses are combined with the leafhopper-susceptible crop as a strip crop, intercrop, or mulch.

Field trials were conducted in 1992 to determine the feasibility of controlling potato leafhopper populations primarily with a fungal pathogen and, in a few instances, with interplanting non-host vegetation. Paired plots of potatoes and snap beans were established and were sampled for leafhopper populations throughout the season. The pathogen was released at approximately half of the potato and bean sites concurrent with high populations of leafhopper. (High leafhopper populations were not present at all sites.) After the pathogen was released, dead or moribund leafhoppers were also collected, placed on water agar, and observed for development of the pathogen. The pathogen was recovered from one snap bean field. Nymph populations at this site steadily declined in both release and control plots. In the potato plots, nymph populations responded variably. Interplanting beans with grasses, vetch and corn produced no positive effects. Leafhopper populations were low this year at the alfalfa sites. In the alfalfa interplanted with grasses relatively low populations of leafhopper were observed. At this point, results are inconclusive as to the feasibility of releasing a fungal pathogen and interplanting non-host crops for control of potato leafhopper.