Do my highbush blueberries have a fungal disease?
I have several blueberry bushes that are developing reddish/purple leaves and berries throughout the summer. This affected the berry bushes last year as well. I am struggling to diagnose the cause and come up with a remedy so I’m hoping to get some guidance. I have had some suspicion of fungal disease and have tried using a biofungicide which does not seem to help. They are planted in loamy soil with compost underneath them and mulched with cedar and compost. I have also tried to supplement with miracle grow to address any nutrient deficiency and have added citric acid to help lower acidity.
Liz Stanley, Horticulture Community Education Assistant
Thank you for your photo and question about your highbush blueberries. It looks like you have nice fruit this year
Blueberry plants generally do not require high amounts of fertilizer, so hold on adding more for now. Fertilizing after mid-summer can create tender new growth that won’t harden off before winter.
Blueberries need a specific pH in order to take up nutrients, so we recommend testing your soil. Kits can be picked up at your county Extension office or we can mail one to you. When you fill out the form, use Crop Code #410 adding a note about how many plants you are growing. You’ll get recommendations from the Maine Soil Testing Service on how to adjust the pH and what you need for nutrients if needed.
Here’s more information about Growing Highbush Blueberries in Maine.