Slow spring brought this benefit pest management

Risk levelmight have been lowered for probleminsect. By Judie Steeves


any people complained about this past winter’s cold and snow, but insect pests also were not too enthusiastic about the weather.

Spring was reluctant to get going this year too, completely the opposite of the previous several years, so pests such as Spotted Wing Drosophila also were slow to emerge.

By late April there still weren’t yet any trap catches of the devastating pest of berries, but then even berries were further behind than many previous years.

However, the provincial agriculture ministry’s entomologist Tracy Hueppelsheuser noted it’s not unheard-of to see significant mortality

of SWD because of a cold winter and late spring. She reports that as of April 21, this year was about 22 days behind 2016, using the SWD Degree-Day Phenology Model, which indicates this year is about the same as the 30-year normal for temperature. That model shows this year is 40 days

behind 2015, which was a very warm and dry year, she reports.

So, she feels this spring’s risk from SWD is low, but warns things can change quickly if the weather warms up before harvest, so she advises growers to not let their guard down with regard to management of the pest. SWD was first identified in B.C. in 2009, but it is native to Southeast Asia and prefers temperatures of 20 to 30 C. Adults overwinter as flies, and with

Spotted Wing

Drosophila on raspberry

warm weather they become active, mate and lay eggs in ripening fruit, producing up to five generations a year. Females average 384 eggs per female and each hatches in 2-72 hours. Larvae mature in 3-13 days and pupae live in fruit or outside for 3-15 days, depending on temperatures. For more information on SWD management, go to the ministry’s website at: dustry/agriculture-seafood/animals-

British Columbia Berry Grower • Summer 2017 11

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