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Looking Ahead

Forages & Grains





Nursery & Forest

Degree Days

Volume 63 Number 17 Date 08/30/2018

BROWN MARMORATED STINK BUG - Fruit growers and homeowners are advised to watch for this pest as the bugs swarm during warm fall days in search of overwintering sites. The brown marmorated stink bug is established throughout much of southern and eastern Wisconsin, with captures in survey traps reported this season from monitoring sites in Dane, Door, Kenosha, Marquette, Racine, and Rock counties. Nymphs and adults usually remain active through October or early November. Any swarms of stink bugs noticed this fall in counties other than those mentioned above should be reported to DATCP at 1-866-440-7523.

CODLING MOTH - Heavy moth flights continued in a few southern orchard locations in the past week, but numbers have declined at most sites. The largest captures of 33 and 15 moths per trap were reported from Iowa and Racine and counties. Apple growers are reminded that evaluating second-generation larval damage by early September will help to anticipate first-generation codling moth pressure next season. Orchards that have recorded captures higher than 10 moths per trap per week since the second flight began in July will likely find visible fruit damage at harvest, if the pest population is established in the orchard. If no damage is observed this fall or less than 1% of fruits are affected, then the source of the moths may be from outside of the orchard.

APPLE MAGGOT - Flies are expected to persist in orchards for 2-3 more weeks, or until about 2,800 degree days (modified base 50F) have been reached. The base 50F accumulation as of August 29 was 2,599 at La Crosse, 2,460 at Madison, 2,257 at Racine, and 2,345 near Green Bay. Apple maggot pressure has been variable but generally low this season. Continued maintenance of red sphere traps is recommended through September.

SPOTTED TENTIFORM LEAFMINER - The third and last flight of the season has declined in most orchards. A few sites in Bayfield and Marquette counties reported higher counts of 306-739 moths from August 23-29, but captures at all other sites were below 111 moths per trap, which is relatively low for this pest. Moth flights are likely to subside by mid-September.

SPOTTED WING DROSOPHILA - This invasive fruit pest will remain a threat to ripening fruit as the fall raspberry season continues. Berry growers are advised to maintain treatment programs. Sprays applied in the early evening, 1.5 hours before or after sunset, will maximize contact exposure with SWD in the canopy since peak fly activity occurs between 6:00 and 10:00 pm. Insecticide rotation is critical for preventing SWD resistance development if short-interval sprays are being used, and pre-harvest interval (PHI) must be followed. Also necessary for SWD control are clean, daily harvests of all mature raspberries and cooling fruits to 34-38F immediately after harvest, if the berries are not being delivered to markets the same day.

-- Krista Hamilton, DATCP Entomologist