Rotting fruit attracts fruit flies. A bruised pear or peach left on the kitchen counter in summer appears to gather flies from thin air. The SWD, however, is different. The female lays eggs in unripe fruit. She has a curved saw attached to her lower abdomen, which she unfolds and uses to slice into the hard fruit. Therein she deposits one to three eggs. Several females can lay eggs in the same fruit. The larvae hatch in a few days, and the cycle from pupae to egg-laying female is complete in two weeks.
In 2011, midway through the raspberry harvest season, a customer called early on Sunday morning. She had picked twelve pints of raspberries for jam the day before and, while she was cooking them, noticed small white worms floating to the top of the pot. After putting the phone down, I raced out to the patch and picked a few berries. Opening one of the soft berries in the palm of my hand, I peered into the center and saw white larvae squirming inside the soft juicy berry. Disgusting!
The SWD came from Japan to California in 2008 and ravaged fruit growers all along the Pacific coast. The loss for California growers in the first year was over 500 million dollars. In the next two years, SWDs traveled across the country, damaging blueberries in the Midwest and, a year later, arrived on the East coast. It’s still here! Soft-skinned fruit like raspberries and blueberries are at the greatest risk, though SWD will also lay eggs in peaches.
Now, six years later, Old Frog Pond Farm is one of only a few fall raspberry patches in the area. Most everyone else I know has slashed their canes to the ground. If you look up the insect, you will see that university research labs across the country are trying to find a biological way to combat it. Chemical pesticides work, but you need to apply them often and production costs increase for the grower. Organic growers have two choices of sprays – one is a spinosad, a natural bacterium that is used as an organic insecticide, and the other is PyGanic, a natural insecticide derived from chrysanthemum flowers. The latter is labeled as ‘poor’ as far as its effectiveness. A formulation with spinosad works well, but it can’t be sprayed more than six times a season, and it is effective for only five days.
In the last few years, I have been trying to get our canes super healthy so they generate resistance on their own and have experienced some success. Last year, the weather was dry and this kept the SWD numbers down. This year, the SWD arrived two weeks early, and the rains have increased their numbers the way water breeds mosquitoes. I am concerned. We have worked so hard to weed the patch twice, to thin the canes, to give this field all the love and attention possible. For our precocious canes, we now go out every day and pick both ripe and any old fruit. Sanitation is key to keeping SWD in check.
Unlike the old days when the fruit would be on the bushes ripening during the week and the weekend pickers would pick the patch clean, we will need to pick ripe berries every day once the season begins. Silferleaf Farm in Concord, the only other local raspberry grower, started making raspberry vinegar with their daily picked berries. We have not yet developed a secondary market, but I am planning to contact regional ice cream makers. I’m open to suggestions — and volunteer pickers. It’s enjoyable and the ‘take home’ will be berries of course!
Now when I wake in the middle of the night with farm anxiety I see raspberries. Yet this will soon pass — for the next three weeks I will be in the orchard thinning apples, removing blemished fruit and doing summer pruning. We have some beautiful apples, but we also have some serious problem varieties due to the wet season. Soon when I wake in the middle of the night I will be seeing apples — the blemished scabby ones and the cascading, out-of-control trees with branches so loaded with perfect fruit they are in danger of breaking. It is a world of ricocheting extremes even on this small farm.