Anthracnose

Plant disease

Description

Anthracnose is a name for several fungal diseases, not a single species. Depending on the plant, the cause may be a Colletotrichum species or another fungus. It affects vegetables, fruit crops, ornamentals, and shade trees. The fungi infect plant tissue during wet weather, often spreading in splashing rain or irrigation water. They can survive on infected plant debris and, in some cases, on twigs or seeds. Damage varies by host: leaves may develop dead patches and fall early, stems may develop dark lesions, and fruit may develop sunken spots that expand into rot. Repeated infections can weaken a plant or reduce its harvest, although established trees often recover from a season of leaf damage. Because several diseases share the name, the exact appearance and best control measures depend on the plant affected. Identifying the host and checking which parts are damaged are useful first steps.

Symptoms

• Spots on leaves
• Brown or crispy leaf edges
• Bleached or scorched patches
• Leaves dropping
• Rotting fruit
• Wilting

How to Identify

Look for irregular tan-to-brown leaf spots or blotches, sometimes concentrated along veins, and dark, often sunken lesions on stems or fruit. Fruit spots may enlarge and show rings or pinkish-orange spore masses in humid conditions. Symptoms differ among crops, so compare them with descriptions for the affected plant. Anthracnose is more likely after prolonged rain or overhead watering. Bacterial spots are often water-soaked or bounded by leaf veins; sunscald usually affects exposed surfaces without spreading lesions. A dark patch confined to the blossom end of a fruit suggests blossom-end rot instead. When identification matters for treatment, a local plant diagnostic service can examine a sample.

Prevention

Choose resistant varieties where available, and buy healthy seed and transplants. Give plants enough space for air movement, thin dense growth when appropriate, and control weeds that keep foliage damp. Water at the soil surface rather than overhead; if sprinklers are necessary, water early so leaves dry promptly. Avoid handling plants while they are wet. Remove fallen leaves, infected fruit, and crop debris, especially at the end of the season. Do not save seed from diseased plants. Rotate susceptible annual crops with unrelated crops, following crop-specific guidance, and avoid planting repeatedly in a known problem area. Prune dead or infected twigs when conditions are dry. Healthy soil, suitable watering, and avoiding plant stress help plants withstand infection, though they cannot guarantee prevention during persistently wet weather.

Treatment

Start by removing infected fruit and badly affected leaves; dispose of them rather than leaving them beneath the plant. Prune infected twigs back into healthy wood when dry, and clean tools between plants. Improve airflow and switch to soil-level watering. These steps limit further spread but will not restore damaged tissue. On established shade trees, treatment is often unnecessary: many produce healthy new leaves once weather dries. If a valuable crop has recurring, severe anthracnose, consider a fungicide specifically labeled for that plant and disease. Some copper-based products are options, but they can injure foliage and affect soil organisms. Apply any product exactly as its label directs, including timing, protective equipment, and harvest intervals. Fungicides generally protect new growth; they do not cure existing lesions. If disease persists, confirm the diagnosis before spraying again.

Plants Affected

Adzuki Bean, American Elm, American Sycamore, Ash, Black Ash, Black Bean, Black Oak, Black Walnut, Blue Ash, Blueberry, Bur Oak, Cannellini Bean, Cassava, Chestnut Oak, Chinkapin Oak, Cranberry Bean, Dogwood, Elm, Flowering Dogwood, Great Northern Bean, Green Ash, Green Bean, Hickory, Hosta, Kidney Bean, Lablab Bean, Lentil, Lima Bean, London Plane, Lupine, Mango, Maple, Navy Bean, Oak, Pacific Dogwood, Pin Oak, Pinto Bean, Post Oak, Red Oak, Ribes, Rubus, Salix, Scarlet Oak, Shagbark Hickory, Shumard Oak, Silver Maple, Slippery Elm, Sorghum, Sugar Maple, Swamp Chestnut Oak, Swietenia, Sword Bean, Sycamore, Ube, Vaccinium, Walnut, Water Oak, Watermelon, White Ash, White Bean, White Oak, Willow, Willow Oak, Winged Bean, Winter Melon, Yam

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