Project Number: 3620-22410-011-03
Project Type: Specific Cooperative Agreement

Start Date: Sep 16, 2008
End Date: Jun 25, 2009

Objective:
1¿Evaluate the level of suberization and weight loss of cut tubers treated with sprout control agents (CIPC, clove oil) over time in storage. 2¿Evaluate the level of suberization and weight loss of cut tubers treated with disease control agents (Phosphorous acid, hydrogen peroxide/peracetic acid mixture, biocontrol agents) over time in storage. 3¿Test if potential changes in the rate of wound healing equate to greater disease (Fusarium dry rot) development.

Approach:
Objective 1: Potato tubers (cv. Russet Burbank) will be grown and harvested at the University of Idaho Kimberly Research and Extension Center. Tubers will be cured for 2 weeks at 55 F, and the temperature decreased 0.5 F/day to a final holding temperature of 45 F. Relative humidity will be maintained above 95% for the study. Within 1 month of harvest, termed "fresh potatoes," tubers will be cut into similar sized pieces with comparable cut surface area. Tubers will be treated with the following sprout control treatment applications: a) EC formulation of CIPC at 1% solution; b) EC formulation of CIPC at 0.5% solution; c) clove oil (Biox C; rate to be determined); and d) untreated control. Three subsets of treated tubers will be used to answer the objectives of the study. (1) A subsample of cut and treated tubers will be weighed periodically to determine weight loss over time (up to 14 days). (2) A second subsample will be evaluated for suberin and wound periderm development. A thin-slice non-staining technique will be used. Each slice will be examined under a UV microscope and the number of suberized cell will be counted and the presence of the wound periderm layer will be evaluated. Slices will be examined 4 to 5 times during the first 14 days after treatment. (3) A third subsample will be tested for potential disease development of Fusarium dry rot. Evaluations will include simple "bag tests" to assess susceptibility to disease development as well as inoculation treatments with Fusarium spp. The cut and treatment applications will be repeated on "older potatoes" at 6 to 8 months after harvest. The same evaluations (weight loss, suberin and wound periderm formation, and disease development) will be assessed. This will allow the comparison of freshly harvested potatoes to stored potatoes in the ability to wound heal and the response to post-harvest treatments. Objective 2: Potatoes will be handled and evaluated the same as described in Objective 1 except the following post-harvest disease control agents will be applied: a) phosphorous acid (12.8 fl.oz/ton); b) hydrogen peroxide/peracetic acid mixture (1:50); c) biocontrol microbial agents; and d) untreated control. Treatments and evaluations will be performed on "fresh" and "older" potatoes as described in Objective 1. Objective 3: Methodology for this objective has been included in the previously described objectives.