Spots On Blueberry Leaves – What Causes Blueberry Leaf Spot

(Image credit: tilzit)

Blueberry shrubs are supposed to have shiny green leaves and round blue fruit. Occasionally, you’ll see that those blueberry leaves have dark spots on them. Leaf spots on blueberries tell you something you may not want to hear: there is something amiss with your plant. If you see spots on blueberry leaves, your shrub has developed one of several blueberry leaf spot diseases. Most leaf spots on blueberries are caused by fungal diseases. Read on to learn more.

What Causes Blueberry Leaf Spot?

Spots on blueberry leaves are usually caused by a fungus and some can ruin an entire crop. If you have blueberry shrubs, you’ll need to learn about what causes blueberry leaf spot diseases and ways to treat them early. The two most common leaf spot diseases are anthracnose and septoria. The fungi causing these problems live in the soil or fallen leaves beneath the shrubs, overwintering there. The fungi are transferred to other plants with rainfall. Another of the main diseases causing leaf spots on blueberries is Gloeocercospora. It doesn’t do significant damage to a blueberry patch, however. Alternaria leaf spot is another fungus that causes blueberries with leaf spot. Fungal diseases often appear in spring when the rains begin. Wet, warm conditions are ideal for fungal diseases to thrive. The organisms overwinter in the soil and become active in moisture.

Treating Blueberry with Leaf Spot Disease

It is interesting to learn about the causes of spots on blueberry leaves. However, the real question that gardeners want answered are about what steps they can take to treat the problem. First, you should try to prevent your shrubs from getting attacked. If you think about this sufficiently early, you can purchase blueberry plants that are resistant to blueberry leaf spot diseases. A second important step is to remove all plant debris from your berry patch after harvest every year. The fungi live in soil but also on fallen leaves beneath the plants. A good clean-up can go a long way to preventing this. If the fungus causing blueberry leaf spot diseases has found its way into your berry patch, tread carefully. Take care not to spread the fungus yourself when you are working in the garden. Disinfect your tools each time you use them. Finally, treating these shrubs with the correct fungicide early can help your blueberries remain vigorous. Take in a sample of leaf spots on blueberries to your garden store and ask for a fungicide that will work. Use it according to label directions.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.