If you’ve noticed dark spots popping up on your apple tree’s leaves, you’re likely dealing with leaf spot disease. It can be a bit alarming to see, but don’t worry—I’m going to walk you through exactly what this means for your tree and how you can help it bounce back.
What should I do if my apple tree has leaf spot?
If your tree is showing signs of leaf spot, your first move should be to prune away the affected areas. Be generous with your cuts to make sure you get it all, and be sure to destroy the infected debris rather than composting it. Most importantly: disinfect your pruning shears immediately afterward so you don’t accidentally spread the fungus to other plants. In very extreme cases where the tree is completely overwhelmed, it might unfortunately need to be removed entirely.
How do I identify leaf spot on an apple tree?
You’ll recognize leaf spot by the reddish, brownish, or sometimes yellowish spots appearing on the leaves. The exact color usually depends on which specific fungus is crashing the party. These spots usually start out pretty small but will grow larger over time as the infection spreads.
By the way: Apple Scab also causes spots in its early stages, but those are typically tiny and have a distinct olive-green tint.
What causes leaf spot in apple trees?
There isn’t just one single culprit, but rather a few common factors that invite the fungus in. Here are the main things to watch out for:
- Too much moisture: Constant leaf wetness from long rainy spells, cool/damp weather, or over-watering.
- Improper fertilizing: An unbalanced diet where the tree gets too much of one nutrient and not enough of another.
- Lack of light: If the tree is planted in a spot that’s just too shady.
How can I prevent leaf spot?
The best offense is a good defense! To keep leaf spot away, focus on solid apple tree care, especially when it comes to consistent watering and balanced fertilizing. Another pro-tip: always clear away fallen leaves quickly. Fungi love to hide out and overwinter in damp leaf litter on the ground.
What is Marssonina leaf spot?
*Marssonina coronaria* is a relatively new fungal arrival from Asia. It causes brownish to black spots on the upper side of the leaves that eventually bleed into one another. As it progresses, the leaves often turn bright yellow with green speckles. Sometimes you’ll even see patterned, dead areas with a reddish-purple border. A dead giveaway for Marssonina is that the tree will start dropping its leaves much earlier in the season than usual.
Quick Tip: Skip the fungicides
I generally recommend staying away from chemical fungicides for leaf spot. These chemicals can be tough on the tree and the surrounding ecosystem. Plus, it’s notoriously difficult to time the application perfectly for the spray to actually be effective. Stick to good maintenance and pruning instead!