Insect Pest Hits Southeastern Berry Growers Hard

Posted By: David Eddy | Email

Spotted wing drosophila (SWD) infestations have been observed at several berry growing locations already this spring, reports a North Carolina State University (NCSU) Extension entomologist.
The infestations have occurred at both untreated research station plots and, to a lesser degree, at treated commercial farms, Dr. Hannah Burrack writes on the NCSU entomology blog.

Hannah Burrack

Burrack, who serves on American Fruit Grower® and Western Fruit Grower® magazines’ Editorial Advisory Board, reminds growers they need to be proactive in preventing SWD infestation.

“I would strongly encourage you to share this information with any berry growers in your area as well,” she blogs.

Burrack says the recent mild winter in the Southeast raised concerns about the potential for early season SWD damage to berries, which were further increased last month when South Carolina strawberry growers observed infestation.

“We have now observed infestation in strawberries, blueberries, and blackberries collected from our research locations in North Carolina” she writes. “Infestation rates are low (less than 1% in most cases), but these observations underscore the importance of proactive prevention of SWD infestation.”

Despite growers’ best efforts, SWD infestation may still occur. There is still zero tolerance for SWD infestation in fresh market fruit, which means that infested fruit is unmarketable. The following is a quick summary Burrack provided in the event of SWD infestation:

1. Sample fruit regularly to detect infestation if it occurs. Sample fruit each harvest by either cutting them open and looking for larvae or soaking them in salt water (1/4 cup salt per gallon). A video that illustrates a salt test can be found here.
2. If you detect infestation, remove as much ripe and ripening fruit as possible and destroy it (by freezing, “baking” in the sun inside a clear plastic bag for a few days, or removing from the site). Eggs or larvae may be present in otherwise sound appearing fruit. Leaving this fruit means that potentially infested fruit is present and could be harvested.
3. Practice excellent sanitation. Thoroughly harvest all ripe fruit and sell or destroy it (if it’s unmarketable). Do not discard culls in the field, and clean up after rain and u-pickers. Unpicked fruit is a reservoir for SWD larvae.
4. Store fruit cold postharvest for as long as possible. Most eggs and larvae do not develop further at temperatures below 40 F, and some may die. If fruit are kept cold, any eggs that may been laid will not hatch, and some may die.
5. Begin or resume an aggressive (once per week if it does not rain, reapplication in the event of rain) spray program. Rotating between at least two modes of action will reduce the likelihood of resistance development.