Progress 05/15/02 to 09/30/04
Outputs
In two growing seasons, randomized plots of pear trees were treated with all possible combinations of calcium chloride and the fungicides ziram and trifloxystrobin (Flint) in a factorial design. Fruit from trees receiving each possible combination of orchard treatments then received postharvest treatment with water, thiabendazole (TBZ), the yeast Cryptococcus infirmo-miniatus (CIM), or biocontrol products Aspire (2002) or BioSave (2003). Each fruit was wounded with a nail, and stored at 31 F for 3 months. Decay that developed at wounds was identified and the percentage of wounds infected was calculated. The experimental design allowed various types of decay management programs to be extracted and compared. Five program alternatives will be described. (1) No chemical treatments in orchard or postharvest resulted in 19.8 % of wounds infected (average of 2002 and 2003 results). (2) A full program of calcium and fungicide treatments in the orchard, but no postharvest
treatment resulted in 5.9 % of wounds infected. (3) A full orchard program followed by postharvest biocontrol with CIM resulted in 2.8 % infection, with Aspire/BioSave resulted in 1.0 and 2.6 % infection, and with TBZ resulted in 5.3 % infection. (4) No chemical treatments in the orchard, but biocontrol postharvest resulted in 5.2 % infection with CIM and in 11.4 and 1.2 % infection with Aspire/BioSave. (5) Using only organic-compatible treatments (calcium in the orchard resulted in 8.4 % infection without postharvest treatment, and in 4.3 % with CIM, 2.0 % with Aspire, and 2.2 % with BioSave. Across all postharvest treatments, orchard treatment with calcium chloride was a significant factor in both years of study, while ziram and trifloxystrobin were significant as individual effects only in 2002. The interaction of ziram and trifloxystrobin was significant in 2003. Across all orchard treatments, all of the biocontrol agent effects were significant in both years, while the TBZ effect
was not significant. These results may be used to identify decay risk levels associated with the various choices of management program presented. All programs were of value, compared with no treatments in the orchard or postharvest. Orchard treatments contributed substantially to decay control; calcium alone reduced decay while calcium followed by ziram and flint (full orchard program) resulted in less decay. Without orchard treatments, postharvest biocontrol results were variable, but the combination of orchard treatment, whether calcium alone or calcium followed by fungicides, subsequently followed by biocontrol treatments generally resulted in the least amount of infection. Programs consisting of diverse elements are likely to be more dependable in providing decay control. A minimum program of calcium in the orchard followed by postharvest biocontrol can provide substantial decay control, where avoiding use of fungicides is desired. In this study, the programs with the greatest
diversity of tactics, integrating calcium, fungicides, and postharvest biocontrol, resulted in the greatest level of control.
Impacts
The results of this study can be used as an educational tool for decision-making in pear production. Pear producers can have greater awareness of the impact of their management choices on postharvest decay, and of the overall decay potential of various management strategies. This will help producers to identify risks and consider optimum practices within a market-based production strategy. Where no fungicide use is preferred, or where fungicide use is to be limited to the orchard, programs evaluated in this project provided reasonable levels of decay control. A program compatible with organic standards, using calcium in the orchard and biocontrol agents postharvest, provided substantial decay control as compared with taking no action against decay. Maximum decay control was achieved with a combination of nutritional enhancement, orchard fungicide sprays, and postharvest fungicide applications. This integrated program should provide dependable control, as it consists of
diverse tactics acting to reduce decay. Economic benefits should accrue from identifying the optimum decay control program that is compatible with production and market strategies.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Without any orchard or postharvest treatments, fungal decay developed in approximately 17% of Bosc pears held for five months in cold storage. Application of calcium in the orchard ("no fungicide" or organic program) reduced decay to 13%, and application of fungicides in the orchard reduced decay to 6%. In each type of orchard program, postharvest application of biocontrol agents further reduced decay. Using a combination of orchard fungicides and postharvest application of biocontrol agents, decay was less than 1%, while the "no fungicide" program of calcium followed by biocontrol resulted in 3-4% decay. Decay levels achieved by all treatment combination choices were defined.
Impacts
Pear producers can have greater awareness of the impact of their management choices on postharvest decay, and of the overall decay potential of various management strategies. This will help producers to identify risks and consider optimum practices within a market-based production strategy. Where no fungicide use is preferred, or where fungicide use is to be limited to the orchard, programs evaluated in this project can provide reasonable levels of decay control. However, maximum decay control was achieved with a combination of nutritional enhancement, orchard fungicide sprays, and postharvest fungicide applications.
Publications
- No publications reported this period
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Progress 05/15/02 to 12/31/02
Outputs
Sequential treatments were applied to Bosc pear trees in a factorial completely randomized design during the summer and fall of 2002. Fruit calcium enrichment via three orchard sprays of calcium chloride in mid-summer, ziram fungicide applied one month before harvest, and tryfloxystrobin two weeks before harvest were applied in all possible factorial arrangements, including untreated. After harvest, a portion of the fruit harvested from each replicate of each treatment were artificially wounded, and all fruit received a simulated packinghouse line-spray of either the yeast Cryptococcus infirmo-miniatus, the yeast biological control product Aspire, the fungicide thiabendazole, or no treatment. All fruit are currently in storage at 0 C awaiting decay development. Results from various treatment combinations reflecting different management and marketing strategies will be compared.
Impacts
It is expected that this project will demonstrate the relative effectiveness of various control tactic combinations, in turn facilitating producer choice among decay management strategies. Different decay control strategies could be applied to satisfy diverse marketing strategies (organic, conventional, or specific export requirements). Overall, the project results should indicate whether or not successful pear storage decay can be achieved without the postharvest application of fungicide, or if control provided by traditional postharvest fungicide treatments can be improved upon by combination with orchard tactics. Furthermore, results should indicate the relative value of management programs without any fungicide treatments (calcium in the orchard + yeast postharvest). If found to be viable alternatives, these programs would potentially reduce environmental impact through reduced fungicide residue on fruit and elimination of fungicide runoff and disposal in pear
packinghouses.
Publications
- No publications reported this period
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