A Holistic Approach to Manage Pests and Nutrients In Organic Cucurbit Production

Bacterial wilt (BW), transmitted by striped cucumber beetles (SCB) (Acalymma vittatum) and Cucurbit yellow vine disease (CYVD), transmitted by squash bugs (SB) (Anasa tristis) are  two major diseases of cucurbits (muskmelons, squash, etc.) throughout the eastern half of the U.S. Many growers currently rely on frequent pesticide applications to manage these insect-pathogen complexes. On the other hand, organic growers are challenged to reach a nutrient balance necessary to maximize yield and quality without affecting the environment and farm economics. The objective of this study was to develop a management system for organic cucurbit crops that integrate extended duration row covers, dairy based compost and Plant Growth Promoting Rhizobacteria (PGPR- Bacillus subtilis) to manage the complexity of insect-pathogen and nutrient levels while maintaining high yields. During the growing seasons of 2009 and 2010 we investigated the use of row covers on muskmelon and squash crops by removing them at flowering, 10 days after flowering started or at the end of the growing season (squash only) to prevent insect pests from contacting plants during critical times.  In addition, we evaluated low and high rates of compost and organic fertilizer (control) for soil fertility management. Seeds were treated with or without PGPR 4 weeks prior to transplanting to induce systemic resistance in plants. For muskmelon removing row covers 10 days after flowering significantly controlled both, SCB and BW disease. Subsequently, yield was increased by 37% and 5% in 2009 and 2010 respectively, over the control treatment (absence of row covers).  For squash row covers successfully controlled SB while yield was increased by 10% (2009) and 17% (2010) when row covers were removed at flowering compared to the control treatment. Interesting, for muskmelon, BW was suppressed by the use of low compost and PGPR. Higher yield was observed in both years when a higher rate of compost was applied in the muskmelon trial compared to lower rates or organic fertilizer. However, there was no significant difference between the low rate of compost and organic fertilizer (control). There were no differences in yield due to the soil fertility treatments for squash on both years. This approach gives an option to organic growers to manage these insect-pathogen complexes and soil fertility while maintaining high crop productivity.

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