Integrated Management of Cranberry Insect, Weed - Disease Pests Using Fall - Spring Floods

Integrated Management of Cranberry Insect, Weed - Disease Pests Using Fall - Spring Floods

Summary

Post-harvest floods on cranberry beds have been shown to eliminate cranberry fruitworm hibernacula (overwintering stage) and to suppress Rubus sp. (dewberries) growth (plots on non-flooded control beds produced about three times more new crowns than did plots on flooded pieces the following year). A three week post-harvest flood in 2000 had no effect on the incidence of Phytophthora root rot. A short post-harvest flood for the removal of trash in 2000 reduced the incidence of the fruit rot fungi Fusicoccum and Phyllosticta in berries sampled during the 2001 growing season. To date, no adverse effect on yield has been found, but reduced fruit set in the year following the flood is being studied further.

Objectives/Performance Targets

The overall objective of this project is to examine the use of flooding (4 week post-harvest; 2-3 week spring; short post-harvest) for the integrated control of cranberry weed, insect, and disease pests; extending our current knowledge of the impact of flooding on certain key pests and developing a strategy for reduced-pesticide management that minimizes adverse cranberry crop and plant impacts. Preliminary observations have shown that post-harvest floods have less impact than spring floods on yield while seeming to offer at least some control of pests.

Accomplishments/Milestones

This project is third stage IPM, integrating harvest methods with management of multiple pests. In 2000-2001 we examined the effects of 4 week post-harvest floods and short post-harvest sanitation floods on cranberry fruitworm (CFW), Rubus sp. weeds, fruit rot, and Phytophthora root rot. Study sites are paired with unflooded control bogs.

Three paired sites were used in 2000-2001 — Cranberry fruit worm emergence was significantly affected by the use of a 4 week post harvest flood. In both instances where a full 4-week flood was held, 100% of the larvae failed to emerge — significantly higher mortality then in the control pieces.

Partial control of dewberry (R. hispidus) was demonstrated in the 2000-2001 season. Even though the number of crowns increased in both flooded and control beds in the summer of 2001, plots on non-flooded control beds produced about three times more new crowns than did plots on flooded pieces.

A three week post-harvest flood in 2000 had no effect on the incidence of Phytophthora root rot. It did, however, impact the incidence of certain fruit rot fungi (specifically Physalospora and Coleophoma) detected in the berries in the 2001 growing season, indicating a possible effect on disease incidence in the year following the flood. A short post-harvest flood for the removal of trash in 2000 reduced the incidence of the fruit rot fungi Fusicoccum and Phyllosticta in berries sampled during the 2001 growing season.

Impacts and Contributions/Outcomes

The use of flooding for pest control in cranberry has the potential to reduce pesticide use and reduce the need for fumigating with harsh chemicals in order to eliminate dewberry prior to replanting the beds. Our outreach plan for this project will be targeted primarily at cranberry growers, industry representatives, and IPM providers. The cranberry industry has taken a sharp downturn recently. Since the methods demonstrated in this project can be less expensive than traditional practices, the likelihood of widespread adoption has increased.

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