Flooding to manage dodder (Cuscutagronovii) and broad-leaved weed speciesin cranberry: An innovative use of atraditional strategy

The implementation of new uses for traditional cultural and pest management practices has been prompted by renewedinterest in sustainable approaches for farming. The use of floods (for various durations) has been an inexpensive andhistorical cultural practice in cranberry (Vaccinium macrocarpon Ait.) horticulture. The onset of a serious economic crisisin the cranberry industry in 1999–2000 brought about an urgent need to find inexpensive methods of pest control thatwould allow growers to remain fiscally solvent. Initially, anecdotal evidence from several farms indicated that holdingshort-term spring floods suppressed dodder infestations. Based on these findings, a 2-year demonstration-style project wasinitiated in 2002 to determine the efficacy of short-term floods (24–48 h) for the management of dodder in cranberry inMassachusetts. The project was expanded to include evaluating a 10-day summer flood for control of broad-leaved weedspecies at one commercial cranberry farm. Species richness and diversity and percentage weed coverage were lower afterthe implementation of the 10-day flood period compared to pre-flood assessments. Weed species dead or not detected afterthe 10-day flood included ground nut, asters, narrow-leaved goldenrod, chokeberry and poison ivy. Comparison of pairedsites (flooded and nonflooded bogs) indicated dodder stem dry weights were lower on flooded areas in three out of the sevenlocations in year 1. At two additional locations, the flooded bog had higher stem weights when paired with a historicallylow-infestation bog, which may have masked any dodder reduction from the flooding practice. In year 2, no differences inthe number of germinated seedlings between any treatment pairs were noted. Data from a cranberry company representing12% of the cranberry acreage in Massachusetts indicated a 65–89% reduction in pesticide use when short-term spring floodswere implemented during 2001–2003 compared to the previous 3-year period. Short-term flooding may offer a sustainableoption that can be integrated into the overall management plan for several problematic cranberry weed species, especiallydodder. Additional research is warranted to further define the most effective environmental conditions needed and tovalidate the efficacy of short flooding events for effective cranberry weed management