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Managing transplant size and advancing field maturity of fresh tomatoes and peppers

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Title: Managing transplant size and advancing field maturity of fresh tomatoes and peppers
Author: Zandstra, J.W.; Squire, R.C.; Watt, G.J.
Abstract: Previous work using the triazole paclobutrazol (Bonzi) on processing tomato transplants involved treating the plants with a 5 ppm soil drench at the 2 leaf stage, and subsequently fertilizing heavily (up to 5 times the normal rate) to achieve the desired plant height. This treatment resulted in increased vigor in the field (measures as plant dry and fresh weight), advanced plant development (earlier bloom), advanced fruit maturity and increased yields. However, it is not presently registered on any food crops in North America, so a registration for use on tomato transplants is unlikely. Work in 2006 included other potential growth regulators with greenhouse registrations (uniconazole- Sumagic; Nova) and food crop registrations (Apogee). Nova and Apogee were not effective, and only Sumagic was evaluated in 2007. As noted with processing tomato transplants, Sumagic treatment reduced transplant growth in the greenhouse, and extra fertilizer was needed to produce a plant of marketable size after 6 weeks. Growth and development was advanced after field establishment, as indicated by increased plant fresh weights and advanced flowering. Late applications of Sumagic (21 days) was less effective. Little difference was seen between the 2.5 and 5.0 ppm rate. Fruit maturity tended to be advanced at both field locations; however significant differences were not noted. A greater percentage of cull fruit (mainly shoulder check) was found in tomatoes treated with growth regulator treatments at one site. While this was unexpected, it may be useful in eliciting the cause of shoulder check.
Description: Total marketable fruit did not differ among treatments at the Ridgetown site (Table 9) but total fruit yield (combination of large, small, cull and cracked fruit) tended to be greater with growth regulator treatment. There tended to be a greater percentage of cull fruit with some growth regulator treatments, which consisted mainly of fruit with shoulder check. Why this occurred is unclear and unexpected. This treatment effect did not occur at the Cedar Springs site (data not shown) Little data was collected from the pepper trial, as it became obvious soon after application that this regime of growth regulator application was not practical for peppers. Pepper plant growth was reduced to a much greater extent than tomato transplants, and in many treatments we were not able to produce a marketable plant in the allotted time even though extra fertilizer was applied. Once planted in the field, the plants recovered and total marketable yields were similar regardless of whether growth regulators were applied or not. Fruit numbers per plant were not affected as well. Valenti has supported this work financially, and data will be shared with them in order to support a minor use registration of Sumagic for managing transplant growth in the greenhouse.
Date: 2007-11-15
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