Paul A. Domoto

Effect of Organic Pest Management Practices on Apple Productivity and Apple Food Safety

ABSTRACT Research was conducted in a certified organic apple (Malus x domestica Borkh.) orchard in 2000 to determine the effect of organic pest management techniques on pest control, apple yields and microbial populations on harvested apples. In Experiment 1, apple colouring bags, sticky red spheres, kaolin particle film, kaolin particle film plus sticky red spheres, or colouring bags plus sticky red spheres were applied to Redfree, Jonafree and Liberty apple trees in a split-plot design. Insects and diseases were sampled in the control and kaolin particle film treatments. Apple yields and insect damage ratings at harvest were determined for all treatments. There was a significant treatment x cultivar interaction related to insect damage on apples. Insect and disease damage ratings throughout the growing season and at harvest were lowest in Jonafree trees treated with kaolin particle film or colouring bags. There was no effect of treatment on beneficial insects during the growing season. Marketability was greatest in the Jonafree apples treated with colouring bags or kaolin particle film. In Experiment II, the effect of the organic management practices in Experiment I on the food safety of harvested organic apples was examined. Microbial populations on untreated apples and apples treated with kaolin particle film or colouring bags were enumerated post-harvest. No E. coli populations were observed on any apples. Low populations (225.0 ± 95.0 colony-forming units [CFU] apple−1) of coliform bacteria were observed on unwashed control apples. Postharvest yeast and mould populations were greatest on unwashed apples treated with kaolin particle film and lowest on apples protected by colouring bags. When kaolin particle film-treated apples were washed prior to analysis, yeast and mould populations were reduced by 50%.

Canopy Management Practices and Light Interception of Northern Grape Cultivars

Introduction The recent development of Vitis riparia hybrids has allowed the expansion of the wine industry into Iowa and the Upper Midwest. These cultivars are more cold hardy and vigorous than traditional V. vinifera hybrids. During maturation the fruit tend to retain high levels of acids, exhibit a rapid rise in pH, accumulate high potassium levels, and possess a different profile of malic to tartaric acid than other hybrids. Wines from these grapes often have a “grassy” or “herbaceous” flavor. These same characteristics have been associated with fruit grown in shaded canopies. This study was undertaken as part of the USDA Northern Grapes Specialty Crops Research Initiative (SCRI) project to assess the effectiveness and cost benefit of various combinations of canopy management practices on improving the fruit quality characteristics of Frontenac, La Crescent, and Marquette wine grapes. This report summarizes part of the first year results.