How to Defend Your Cherry Tree
Around here it’s cherry pie on the Fourth of July, not apple. I have a North Star dwarf cherry tree in my front yard that is always ripe in the first week of July. I chose the dwarf variety so it would fit comfortably by the driveway under the power lines and not get too big for me to manage. I chose North Star because I love a really tart cherry pie, and the folks at the U of MN are always sure to put out a winter-hardy tree. I think it’s been in place six or seven years and is really hitting its stride now. I had a fantastic crop of cherries this year, and I couldn’t be more pleased. Between the brown rot fungus, the spotted wing drosophila, the birds, and the chipmunks, I’ve really had to go without cherries for the last several years, but I’ve learned from my mistakes, and this year has been a big win with two heaping mixing bowls, totaling about 15 pounds.
It helps a lot to have dry weather. It’s easier to add water to a tree than to dry it out in hot, humid, rainy weather. Once your tree has brown rot, it never really goes away–the spores are always there somewhere, waiting to get going. This year has been so dry that they never really had a chance to sporulate, so I was left with bright, shiny, red cherries instead of mummified crust balls.
Drosophila suzukii, or the spotted wing drosophila (SWD), is a new nemesis in the gardening world. It’s a fruit fly that does not damage healthy fruit, but if your fruit has been damaged by a hail storm or, say, the beginnings of brown rot fungus, then the female fly will lay her eggs in the fruit and they will hatch, eat the fruit, pupate, and turn into an adult inside your cherries. Then when you pick them they are a bit mushy and have a hole in the side with a nasty little maggot that pokes his head out and waves at you when you squish the cherry. I know this because I squeezed an entire mixing bowl of cherries one-by-one to make sure I didn’t accidentally eat any maggots. I also know now, that if you put your cherries in a bowl of water, the maggots will drown and float to the surface in a really revolting manner. But then you’re not sure which cherries they came from, so there’s really nothing for it—you’ve got to squish each cherry.
North Star Dwarf Cherry Tree—Tart cherries, not very good for snacking, but excellent for pies.
If you’re like me and you’re not interested in using chemicals to defend your fruit, the only thing you can do to combat the SWD is remove damaged fruit as it occurs, or cover your tree with a fine mesh net and hope for the best. I opted for the latter, and was happily rewarded this year, but I have been fascinated by the possibility of enlisting the aid of the hummingbirds. One of the natural predators of the fruit fly is the hummingbird, and a study done by Cornell University back in 2018 found that luring hummingbirds into a field of raspberries with bird feeders reduced SWD fruit infestation compared to a raspberry field without hummingbirds. Presumably, if you can just get the hummingbirds near your cherries they will find the SWD and eat them. After my experience with maggot squishing, I’m planning on planting a bunch of red flowers around my cherry tree, and maybe a hummingbird bird feeder or two. I’ll let you know if it works out.
A fine mesh net will keep most critters away.
Bird netting has been an essential tool in defending my cherry crop. As soon as those cherries start to look pink I know the birds have got their eye on them. Birds depend mostly on their vision to navigate life. They don’t have much of a sense of smell, but they have excellent color vision, just like we do, and through the ages the plants that had red fruit were the ones that were most successful at having their seeds dispersed by birds that would find the fruit, eat it, fly away, and poop the seeds out elsewhere along with a nice little pile of fertilizer. If you remember back to art class, opposite green on the color wheel is red, so the color that will be most visually striking against a background of green foliage is red. And so as soon as the green cherries begin to turn to red, I know it is time for the net. The same fine mesh I put over the tree to prevent the SWD also does a good job of keeping out the birds.
But not the chipmunks. One year I lost the whole crop to a chipmunk that got himself caught inside the net and then couldn’t find his way out again. Don’t worry, he found plenty to eat while he was in there, but it was a very tense time for both of us trying to figure out how to get him out and untangled.
After all of these gardening trials I have two full mixing bowls and about four hours of hand-cramping cherry pitting to look forward to. I’m expecting two batches of jam and maybe six quarts of cherry pie filling this season. That ought to hold me until next year.
Many hours of pitting ahead
