SWD destroy fruit

Q. Last year’s crop of raspberries was ruined by fruit maggots. Is there something I can do to naturally prevent this from happening in 2015? Perhaps pruning?

June from Mineral Ridge

A. The “maggots” you have in your berries are spotted wing drosophila (SWD). This is a relatively new pest on fruit crops in Ohio. The adult is a fruit fly, similar to what you see flying around your house when you have rotting fruit in the trash can.

Yes, the normal fruit flies feast only on rotting fruit. SWD is different, and destructive. SWD feasts on just-ripening or just- ripened fruit while it is still attached to the plant. The adult female makes a tiny scar on the surface of the fruit and lays her eggs there. The hatching larvae feast on the ripening fruit from the inside of the fruit (for the most part). The larvae pupate in about seven days. There is one generation every eight-16 days, with each female laying 350 eggs.

SWD will destroy fruit quickly. A farm with this problem can lose an entire crop before they know what happened. In 2014, we had traps on three farms in the county, trying to get an estimate of what is happening on certain crops. We use clear peanut-butter containers with red lids, with mesh over holes cut into the sides and apple-cider vinegar inside to catch any SWD in the area.

For homeowners, the best way to check for the larvae is the salt test. You simply put fruit in zip-top bag or in a pan. Add 4 cups warm water and 1/4 cup salt. Wait 15 minutes and examine the top of the water for floaters.

For natural (versus organic) control, sanitation is the only option. Pruning will do nothing. The insect still will be around. You will need to eliminate all overripe fruit from the area and pick just before perfect ripeness. Even if you can accomplish this and keep up on a daily basis, this option does not work. You still will be eating the “extra protein” when you eat your berries.

There are many options for organic control, though: spinosyns (in some formulations) and pyganic are both organic. You must read and follow all label directions on any product you spray (organic or not).

For details on all control options (including some organic controls), how to build a trap and other details, go to: http://go.osu.edu/spottedwing.

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hotline at 330-533-5538 to submit your questions. Clinic hours vary this time of year due to the winter season.