CRANBERRY GENETIC IMPROVEMENT AND INSECT PEST MANAGEMENT
Location: Vegetable Crops Research Unit
Title: Flooding as “spring cleaning” for insect pests
Submitted to: Wisconsin State Cranberry Growers Association
Publication Type: Proceedings
Publication Acceptance Date: August 1, 2012
Publication Date: August 8, 2012
Citation: Steffan, S.A., Singleton, M., Sojka, J., Zalapa, J.E., Dittl, T. 2012. Flooding as “spring cleaning” for insect pests. Wisconsin State Cranberry Growers Association. p. 32-34.
In 2011, a large-scale field study was undertaken to examine how a 30-40 hour spring flood (550-700 DDs) 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. Among the major insect pests of cranberry, only black-headed fireworm (Rhopobota naevena) populations were significantly reduced by the floods, when compared to the non-flooded beds. This focus on major pest species, however, overlooked the benefits that flooding conferred on the suppression of various background pest species. Samples of the detritus removed from floodwaters were examined for arthropod fauna, and these samples yielded many noctuids, tortricids, and scarabs. From this work, it was revealed that flooding eliminated tremendous numbers of arthropods from the cranberry beds as growers removed the accumulated “trash.” Spring flooding, therefore, not only may reduce pest populations via drowning but also by physically removing the pests. These findings underscore the importance of removal of detritus from beds during a flood, as well as the prompt transport of “trash piles” away from the marsh.