Developing Integrated Pest Management Strategies to Reduce Damage from the Invasive Allium Leafminer on Organic Farms

View the project final report

Commodities

• Vegetables: garlic, leeks, onions

Practices

• Crop Production: application rate management
• Education and Training: demonstration, extension, on-farm/ranch research
• Pest Management: chemical control, cultural control, integrated pest management, mulching - plastic, row covers (for pests)
• Production Systems: organic agriculture

The invasive insect pest allium leafminer (Phytomyza gymnostoma Loew) (ALM) has the potential to devastate commercial plantings of crops like scallions and leeks in the Northeast. The allium leafminer has already been found in five states in the region and continues to spread. Researchers have identified several potential conventional insecticides to reduce the risk of damage from ALM, but little work has been done to evaluate cultural control tactics like reflective plastic mulch, floating row cover, and insect exclusion netting for their potential to manage the pest. This project aims to test the efficacy of these cultural control tactics at reducing damage from ALM and measure their possible impact on marketable yield in spring transplanted scallions and fall leeks. The research will compare the efficacy and cost of implementing these cultural control tactics to a single strategically-timed application of an OMRI-approved spinosad formulation in combination with the use of reflective mulch. Results from the two trials will be synthesized into management recommendations for organic allium growers in the region and shared through extension newsletters, a podcast, and at regional grower conferences. These outreach efforts will reach over 5000 growers and cooperative extension staff directly; however, the permanent resources created as a result of the project will be publicly available to all commercial allium growers in the Northeast who are likely to be faced with the challenge of managing allium leafminer in the future.

This project seeks to answer the following questions:

1) Can the combined use of reflective mulch and a single OMRI-approved insecticide application serve as a viable alternative to the use of row covers to reduce damage from ALM on commercial farms in the northeast?

2) What, if any, increase in marketable yield can allium growers in the region expect from the addition of an insecticide application to the cultural control approach of just using metalized reflective mulch?

3) Does the additional expense of purchasing insect exclusion netting result in an increase in marketable allium yield when compared to the use of floating row cover to protect plants from ALM adults?

4) Can growers apply row covers to allium crops for only a portion of the adult ALM flight to reduce negative impacts to yield and quality while maintaining protection from ALM damage?

If the project is successful, farmers in the region will gain access to research based recommendations on how to reduce damage to high value allium crops from ALM. The input expenses, labor tracking, and marketable yield data analyzed and interpreted will empower growers to make more informed decisions about sustainable management of ALM in the future.