Integrating Cover Crops as Potential Weed and Pest Management Strategy in Organic Vegetable Farms in South Texas

View the project final report

Commodities

Practices

• Crop Production: cover crops, pollinator habitat
• Education and Training: on-farm/ranch research
• Pest Management: biological control
• Production Systems: agroecosystems, organic agriculture, organic certification
• Soil Management: organic matter

The use of cover crops provides both direct and indirect benefits to agricultural ecosystems. Cash crops sown after cover crops directly benefit from better nutrient availability, increased moisture retention, and improved weed suppression. Although there is some evidence, we still lack a complete understanding on the effects of cover crops as an insect herbivory suppressor, and the mechanisms that mediate these effects, if any. To test this, we planted two commonly used leguminous cover crop species, sunn hemp, Crotalaria juncea, and cowpea, Vigna unguiculate in an organic farm in South Texas and observed their effectiveness in providing pest management while also attracting beneficial insects. Data was collected on plant height, insect damage, and plant biomass, in addition to insect community composition in the field. Our preliminary results on cover crops suggest that sunn hemp performed significantly better in all measures, and continuously showed significantly lower pest damage (caterpillars, true bugs, and aphids) along with a high prevalence of beneficial insects (Coccinellids, wasps and bees) when compared to cow pea. Sunn hemp also improved (higher species richness) the surrounding insect community in the area and thrived in the summer heat without much resource input.

The specific objectives of this project were to:

1. Determine the impact of cover crops on the tri-trophic interactions of insects in organic vegetable systems. 
2. Determine the weed suppression potential of cover crops in organic vegetable systems.