Blueberry Drop

Asked May 22, 2018, 2:14 PM EDT

Hello, I have four varieties of blueberry shrubs, 3 in large containers and one planted directly. I planted them about 4 or 5 years ago. Every year since I stopped pinching off the flowers, I've noticed some of the berries either fall off the bush before they're mature, or others look withered and fall off before they mature into berries. The rest of the plant looks relatively healthy, with some occasional signs of pests. (A couple chewed leaves, visible ants, some browning on the bark of the canes.) But overall there are plenty of new healthy looking leaves and shoots. Most of them have a decent amount of healthy berries (with the exception of one that took some serious damage during our ice storm a couple years ago). Occasionally the end of a branch will wither and brown. I tend to prune things that look like that and try to keep the wilted berries in the compost bin. Is it mummy berry? Is it some other type of fungus? Did they not get pollinated? Since the plants keep coming back and I have had decent yields, I haven't considered getting rid of them, but it would be nice to know what I'm up against! Thanks,

Multnomah County Oregon blueberries

1 Response

Hello,

There is a few reasons for this to happen. Fruit set depends on pollination, so you can expect to have flowers that did not develop and "drop" because they didn't get pollinated. This will always happen, as you can not get 100% fruit set generally. I think this probably what is happening to you and you do not have a great population of pollinators in your area. Honeybees are not great pollinators of blueberries, native and bumblebees do a much better job with Vaccinium species. If you count and collect some data we can determine what percentage of fruit set you had and then see if you have actual fruit drop (which is related to a virus).
This is not usually a fungal disease, but you can send your samples to the OSU plant clinic if you are concerned, to get confirmation. And no, those pictures are not mummy berry. If that was the case your fruit would look like dried up mummies with spores and you would see the fruiting bodies of the disease on the ground.

Please send me an email with your contact information to
javier.f-s@oregonstate.edu and I can give you a call to go over fruit set, data you need to collect and things you need to do.

Hope this helps,