Reflective mulch to repel thrips in onions

View the project final report

Commodities

• Vegetables: onions

Practices

• Crop Production: application rate management
• Education and Training: demonstration, extension, on-farm/ranch research, participatory research, workshop
• Farm Business Management: budgets/cost and returns, agricultural finance
• Pest Management: cultural control, economic threshold, integrated pest management, mulching - plastic, prevention

Sweet onions, grown on black plastic, are an important commodity for Northeast fresh market vegetable farms. Onion thrips (Thrips tabaci) are an annual pest capable of significantly reducing yields. Current IPM recommendations establish a very low threshold, and “tight” spray schedule for thrips using conventional chemicals. The result is up to 12 sprays per season with field Environmental Impact Quotients ranging from 126 to 414 (high). Growers anecdotally report that populations quickly rebound from chemical sprays. Resistance to commonly sprayed pyrethroid insecticides in thrips has been documented in all regions of New York by Cornell University. Organic growers using the same IPM action thresholds as conventional farmers, report marginal control with OMRI approved materials. Black plastic mulch has become popular with Northeast onion growers as a cultural form of weed control. However, silver, reflective mulch has been documented to reduce species of thrips on tomatoes, pepper, gladiolus and others. Could we achieve the weed suppression of black plastic mulch combined with the insect repellency of reflective mulch? To date little work has been done on silver mulch for sweet onion production in the Northeast US. This project would endeavor to document and encourage the use of reflective mulch as a viable pest control strategy to reduce the use of insecticides and increase the profitability of mulched onions for Northeast fresh market vegetable growers.

Three cooperating farms in distinct regions of New York State will work with the PI to establish trials comparing silver mulches to black plastic for the repellency of onion thrips. A randomized complete block design will be used. 4 treatments (see table) will be replicated 4 times at 3 sites. Extension staff will calculate mean thrips numbers per plant weekly. Growers will apply spray materials based on threshold levels collected by extension staff. Yield data in pounds and grade will be collected at the end of the trial. Results will analyzed with ANOVA and treatments means separated using Least Significant Difference. An economic comparison of the treatments will be calculated including mulch, spray and labor inputs vs. marketable yield paired with price.