Spore Exclusion - A New Approach to Downy Mildew Prevention in Cucurbits

Project Overview

Project Type: Farmer
Funds awarded in 2009: $8,541.00
Projected End Date: 12/31/2009
Region: Northeast
State: New York
Project Leader:
Louis Lego, Jr.
Elderberry Pond


  • Fruits: melons
  • Vegetables: cucurbits


  • Crop Production: food product quality/safety
  • Education and Training: demonstration, on-farm/ranch research
  • Farm Business Management: feasibility study
  • Pest Management: cultural control, disease vectors, field monitoring/scouting, integrated pest management, prevention
  • Production Systems: transitioning to organic, holistic management
  • Sustainable Communities: sustainability measures

    Proposal summary:

    Current issue

    New downy mildew (DM) strains that do not overwinter in the Northeast but, rather, move north during the summer on southerly winds have nearly shut down the production of cucumbers and netted melons in this region. These strains of the fungus Pseudoperonospora cubensis are resistant to most conventional and organic fungicides. Cucumber and melon varieties that were resistant to previous DM strains show little or no resistance to the new strains.

    In a quick test carried out at the end of last season, we found that if a planting is completely shielded from DM spores using a tightly woven row cover that had been soaked in an organically approved formulation of potassium bi-carbonate (Milstop), no infection from the spores occurred. A control planting seeded at the same time without the cover was devastated by the disease.

    Project objectives from proposal:

    In this proposal we will carry out a much more controlled evaluation of this approach to DM prevention, that of barrier protection. We will test both treated and untreated row covers as well as a low poly tunnel that is fitted with a HPPA (High Performance Particulate Air) filter capable of blocking the DM spores. The enclosures will be carefully constructed to minimize the exposure to spores, yet allow for harvest entry and pollination.

    If successful, this unique approach will allow for the production of these and other cucurbit crops with little or no fungicide applications and using varieties that have little or no DM resistance. It could break the chain of “new chemistry” fungicides resulting in genetic changes to the fungus requiring more “new chemistry” fungicides. I would also lead to the design and use of simple hoop-house structures designed for spore exclusion.

    This proposal builds on the work done at NC State to study DM spores and predict their movement into the Northeast through the North American Plant Disease Center website.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.