Submitted to: North American Cranberry Research and Extension Workers Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2011
Publication Date: September 14, 2011
Citation: Steffan, S.A., Zalapa, J.E., Singleton, M., Harbut, R. 2011. Re-visiting spring flooding as an IPM approach in Wisconsin cranberries [abstract]. North American Cranberry Research and Extension Workers Annual Meeting. p. 18. Technical Abstract: For over 100 years, flooding has been used to suppress arthropod pests of cranberries, yet questions remain as to the trade-off between pest control and flood-induced plant damage. In Wisconsin, there is much interest in the spring flood as a means to not only reduce pest populations, but also to facilitate marsh sanitation and provide frost protection. A large-scale field study was undertaken in 2011 to examine how a 30-40 hour spring flood (late May) would affect key insect populations, as well as the cranberry plant. A total of 46 beds were included in the study (23 pairs of flooded/unflooded beds across 11 marshes in central Wisconsin), focusing on ‘Stevens,’ ‘Ben Lear,’ and ‘GH1’ cranberry varieties. In parallel, greenhouse trials were initiated to investigate the submergence tolerances of these three cranberry varieties, under two temperature and three submergence duration regimes. To-date, it appears that cranberry plants in the field were unaffected by the flooding, and that there were no differences in submergence tolerance between varieties. Conversely, populations of black-headed fireworm (Rhopobota naevena) and cranberry fruitworm (Acrobasis vaccinii) appear to have been suppressed by the flooding. Most growers sprayed insecticides on unflooded beds, effectively rendering pest populations very similar between flooded and unflooded beds, suggesting that the flood served as a replacement treatment for insecticides. Collections of detritus floating atop the floodwaters were examined for arthropod fauna, and these samples yielded many noctuids, tortricids, and scarabs. In the greenhouse, data to-date suggest that cranberry plants can endure prolonged submergence (4 days) in either warm or cold water. Only extreme hypoxia (< 3 ppm dissolved oxygen) caused damage to the apical tissues of current-year uprights. This is an ongoing study, still in its first growing season, so data are preliminary, and conclusions remain tentative.