Q: About four years ago, our raspberry patch was overtaken by spotted wing drosophila flies. The inside of every berry had little white larvae. We were advised to use some sprays but we were reluctant to do that. A second suggestion was to cut the canes to ground level, but the next year we found the same infestation. We reluctantly dug up the entire patch. If we planted new plants, will we incur the same problem? — Shirley F.
A: Spotted wing drosophila is an extremely aggressive fruit fly that lays eggs in ripening fruit of raspberry, strawberry, Juneberry, honeyberry, cherry and many others. The eggs hatch into small white larvae inside the fruit, making it less palatable and mushier.
Unfortunately, cutting down the raspberry canes and digging up the patch won’t eliminate the problem. Spotted wing drosophila flies travel great distances each spring, arriving in time to damage fruit crops from late June on.
You can try locating apple cider vinegar traps and immediately removing overripe berries, but that rarely gives adequate control. Luckily there are two insecticides, malathion and spinosad, that can be used quite effectively and are rated by the Environmental Protection Agency as having only a one-day waiting period between spraying and safe consumption of raspberry fruit.
Malathion and spinosad, which is approved for organic operations, should be alternated, because these flies easily develop resistance if the same product is used continually. Both products are effective for about six days after application. A cycle can be developed of spraying malathion, waiting at least one day, harvesting berries until the seventh day, spraying spinosad, waiting at least one day, harvesting until the seventh day, and so on.
Q: Please help us with an ongoing issue at our community golf course. We have spruce and pine trees on the course and many of them are in the line of flight for golf balls. Some members and staff want to trim the spruce trees up from the bottom to help golfers retrieve golf balls and also to aid in maintenance and mowing. Other members don’t believe the evergreens should be trimmed at all. What are your thoughts? — Stephen B.
A: Whether to prune away and elevate the lower branches on evergreens, or allow the branches to sweep the ground, has been the topic of many marital discussions, not necessarily harmonious.
Unfortunately, there’s not a right or wrong answer. If you’ve noticed evergreen forests where trees grow closely spaced, the lower branches usually die as competition shades them out. Lack of lower branches might be considered a natural trend in a forest setting.
However, when evergreens are well-spaced, their natural tendency is to retain their lower limbs, especially spruce, the evergreens with needles that are an inch long. Pines, which have needles that are 4 to 6 inches long, tend to lose lower branches with age, regardless of spacing.
I’ve not seen any research that indicates damage from removing the lower branches, although pruning wounds on any trees are areas in which pathogens can enter. There are opinions about aesthetics, though, such as this from University of Wisconsin: “DO NOT remove lower evergreen branches, as this destroys the natural form of the tree.”
Personally, I prefer the natural look of evergreen branches sweeping the ground, or elevated only a few inches for easier grass trimming. Once branches are removed, there’s no going back, although I can understand the difficulty of retrieving golf balls.
Q: I know you’ve answered this many times, but I can’t remember when the recommended date is for starting tomato seeds. I want to get a few plants started, but always plant too early and they get spindly. Is now the time? — Bob M.
A: The best date for starting tomato seeds indoors is April Fool’s Day, April 1, which is easy to remember if you consider we’re all fools for a vine-ripened garden tomato. Started April 1 in a seed tray and transplanted into packs or pots when the first true leaves appear, the plants will be just right for planting into the garden by mid-to-late May.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at email@example.com. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.