Small-scale diversified fresh market growers who grow onions intensively in the Northeast U.S. are constantly challenged by yield losses due to bacterial bulb decay, which greatly compromises the profitability of the crop. If bacterial diseases cannot be managed, this industry will not be sustained or expanded. The focus of this project was to evaluate, demonstrate and encourage adoption of cultural tactics including plant spacing and mulch type. We worked with two grower cooperators and conducted three on-farm small-plot research trials in Pennsylvania and New York. Results showed that as plant spacing decreased, plant size decreased, maturity hastened, marketable yield increased, bulb size decreased, and bacterial bulb decay decreased. In the NY trial, narrow 4” plant spacing with 3 and 4 rows per bed provided 63% control of bacterial bulb decay at harvest compared to the grower standard (8” plant spacing with 4 rows per 3 ft bed). The narrow 4” plant spacing with 3 and 4 rows per bed had 1.4 and 1.5 times higher yield and net $109 and $142 more per 100 feet of bed, respectively, than the grower standard. In PA, we were unable to evaluate the effects of plant spacing and mulch type on bacterial bulb decay, because incidence was extremely low. We shared our results with 394 and 238 small-scale growers in NY and PA, respectively, via 11 educational meetings and tours, a conference proceeding and a newsletter article. Internationally, our results were presented to 160 participants at the National Allium Research Conference, and published in the trade magazine, Onion World. We anticipate that 20 growers in NY and PA will experiment with narrow plant spacing and/or an alternative to black plastic in 2011. This NESARE award enabled us to get promising results in a single year of study that in turn leveraged us an additional $219,506 in research dollars to continue our studies of bacterial diseases of onions in both small- and large-scale production. Ultimately, we will have the research base to develop a comprehensive Integrated Pest Management program for bacterial diseases of onions that will sustain the profitability of this industry in the Northeast US.
The focus of this project was to evaluate, demonstrate and encourage adoption of cultural tactics to reduce bacterial decay in small-scale intensive production of onions grown for fresh market. We evaluated the effects of plant spacing and mulch type on plant size, maturity, incidence of bacterial decay, yield, bulb size and economic return.