Here is the newest issue of Massachusetts Berry Notes from the UMass Extension Fruit Team.

Massachusetts IPM Berry Blast

July 21, 2016

All sites being monitored by the UMass Fruit program are now reporting sustained trap captures, though at very low levels.  See article below for thoughts about why SWD populations are slow to increase this year.  If drought and heat are the main reason, then if/when this weather pattern changes, SWD populations can increase rapidly. 

Our recommendation is to continue to employ the 4-pronged management program:
  1. frequent and thorough harvest every 2-3 days,
  2. sanitation (no cull fruit left in the field),
  3. rapid cooling of harvested fruit, and
  4. a spray program with recommended rotations of conventional or organic materials on a 7-day cycle (see here for table of recommended materials).
To assess the effectiveness of your program, we also recommend that you perform a salt flotation test on harvested sound fruit (not cull fruit), on a regular basis.  The protocol for this test can be found by going to
salt flotation test

SWD Egg Laying – Extreme Drought & Heat
Anna Wallingord, Cornell Univ.

The earliest ever arrival in New York State of this fast-reproducing insect rang alarm bells in anticipation of heavy infestations in early or mid-season berry crops that often escape damage. However, larval infestations have been curiously low in summer raspberry and blueberry crops sampled in many areas, including the Finger Lakes region. We suspect that the hot, dry conditions we have been experiencing could explain these low infestations.

swd breathing tubes on blackberry (Cornell swd blog)


Small flies like SWD are sensitive to desiccation (drying out) and therefore prefer to lay their eggs in darker, more humid conditions. SWD are more likely to lay eggs in shaded fruit, lower in the plant canopy, and even prefer laying eggs during the cooler, low-light conditions of dusk over other times of the day.

A halt in egg laying is reported in California when conditions are dry and temperatures climb above 85-90°F. A recent study conducted by our colleagues in Oregon has found that humidity not only plays a positive role in egg laying behavior, but also in the number of mature eggs carried by female SWD. (Tochen et al. 2016. Humidity affects populations of Drosophila suzukii (Diptera: Drosophilidae) in blueberry. J. Appl. Entomol. 47-57.) In other words, a female exposed to more humid conditions will make a greater investment of resources to grow new eggs and she will choose to lay more of those eggs.

This sensitivity to hot, dry conditions may explain the curiously low infestation rates we’ve seen so far in 2016, given the high daily temperatures and drought conditions. And, there are significant implications for management. Plant canopy management may be an important cultural strategy for SWD control. In addition to improving fruit quality, proper pruning can open up plant canopies. An open canopy aids in better spray coverage when applying foliar insecticides and also helps in decreasing the humidity within the microclimate of that canopy. There are ongoing studies taking a direct look at the effects of pruning and humidity on SWD infestations, so stay tuned for more information in the future.

This post was contributed by Dr. Anna Wallingford, postdoctoral research associate, in Dr. Greg Loeb’s small fruit and grape entomology program, Cornell University, NYSAES, Geneva, NY.

(Source: NYS IPM Program SWD Blog @
Archived IPM Berry Blasts are available at the UMass Extension Fruitadvisor website.
Where brand names for chemicals are used, it is for the reader's information.  No endorsement is implied, nor is discrimination intended against products with similar ingredients.  Please consult pesticide product labels for rates, application instructions and safety precautions.  The label is the law.  Users of these products assume all associated risks.
We thank Nourse Farms for their underwriting of this newsletter which allows us to keep subscription rates low.
This work was supported in part by funding provided by USDA-NIFA Extension Implementation Program, Award No. 2014-70006-22579

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