Diseases affecting Japanese Maple Trees.

Common diseases affecting Japanese maple trees

Anthracnose
This leaf blight disease affects many trees including Japanese maples. The disease is most common during warm and wet conditions. Symptoms are leaves with small round reddish purple spots. Many spots can develop into larger irregular patterns and then completely cover the entire leaves. Controls include avoiding wetting the foliage late in the day, improving air circulation with fans, keeping greenhouse doors open and or controlling with chemicals from your local nursery or garden center.

Botrytis
This fungus also known as gray mold affects mostly dead or damaged plant tissue, Although, if left untreated botrytis can cause major damage to entire crops. This disease is also most aggressive in warm and wet conditions. Treatments include improving air circulation, avoiding wet conditions, pruning and properly discarding affected plant material, and chemical controls.

Fusarium
This fungus mostly creates problems in young seedlings. Damage shows up as brown or black lesions within the stem tissue at ground level. The seedlings will then start falling over. The disease can also affect other parts of the plant like stems and new buds. Control includes increasing air circulation, avoiding wet conditions and chemicals.

Verticillium
This fungus born disease is one of the most destructive diseases to affect Japanese maples as well as other plant species. Symptoms of this disease are brown or black streaks within the cambium layer of the affected limb or branch, bbcausing death of limbs, branches or entire trees. This disease is easily spread by mechanical means like pruning with infected tools. Moderate control can best be achieved by pruning out affected plant material with sterilized pruners or clippers and burning. No known chemical control is available.
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