Fruit that has dropped to the ground in orchards and berry plantings provides resources for SWD — food and reproduction. Populations of SWD are climbing. SWD made up almost half of the fruit flies caught in traps in an unsprayed research site where ~300 were caught in four traps. I've seen lots of fruit flies (of various species, including the distinctive male SWD) flitting around the dropped apples in my yard that have been chewed on and pecked at by chipmunks, squirrels, and my chickens (this particular apple tree has been defoliated by apple scab this year and won't carry the crop.)
WEEDS! Pokeweed fruit are starting to ripen; SWD thrives in those fruit.
We've got a long way to go before the SWD season is over. This is the time of year that management has to be consistent and constant:
- maintain an appropriate insecticide program
- routinely sample fruit with salt flotation to check for larvae
- keep weeds down
- prevent leaks in irrigation systems (gosh, it's like a water paradise for SWD!)
- keep plants well pruned and staked
- remove cull fruit from the planting or drop it to the ground
And, while I'm on the subject of cull fruit, I've revised the SWD insecticide guide for treating dropped fruit on the ground. Here's the link to the Quick Guide to SWD insecticides for treating dropped fruit, www.hort.cornell.edu/fruit/pdfs/swd/drop-cull-insecticides.pdf . Make sure to refresh your browser so you don't pull up last year's — the new one should say August 2019 on it.