Brown rot
Brown rot is a common fungal disease causing damage to many types of fruit trees. The same symptoms are caused by two different species of fungi, Monilinia fructigena, infecting apple, pear, almond and quince and M. laxa on plum, peach, apricot, cherry and nectarine.
Typical symptoms
Symptoms of brown rot
The fungus causes brown patches and rot on fruit, often accompanied by blossom wilt, spur blight and wither tip of shoots and flowers.
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Fruit: Soft brown patches enlarge to engulf the entire fruit, either on the tree or in storage. The fungus can spread quickly in storage, infecting undamaged fruit by contact. White spore bearing pustules may appear on the brown patches, often in concentric rings. Fruits shrivel and become mummified. They may drop or remain attached to the tree.
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Blossom wilt: In spring, blossoms turn brown and wilt. They usually remain attached to the twig. In wet weather, fungal spores multiply and spread quickly, causing more floral infections. Spores can spread to spurs resulting in canker development on the twigs.
Spur blight: Leaves wither on the spur. This may develop into a small canker having tufts of grey fungal growth.
Wither tip: Leaves wither and develop brown lesions, tip droops. Aphids may be present.
Life cycle
Spores overwinter in mummified fruit or in twig and branch cankers. In spring, spores are released to be carried on the wind, by insects or by rain-splash. Blossoms and young shoots are the first to become infected. The fungus spreads quickly into the spur or branch to form canker. The fungus enters fruit via wounds or cracks created by frost, hail, birds, or insect pests. Careless picking and handling at harvest allows entry of spores that cause post harvest losses in storage. Infection is accelerated in hot and humid conditions two to three weeks prior to harvesting.
Prevention and control
Garden hygiene: Remove all rotting or mummified fruits from trees and collect up fallen fruit from the ground.
Cultural control: Prune out wither tip and spur blight as soon as it occurs. In winter, cut out cankers and brown lesions on stems and branches.
Storage: Avoid damaging fruit during harvest. Do not store bruised and stalk-less fruit. Use clean containers for storage of fruit. Check stores regularly and remove any fruit with signs of rot.
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Foliar feed: Use seaweed extract as a foliar feed to boost the trees’ resistance having a beneficial effect. Apply it every 10-14 days from bud-burst to green cluster stage and then again from petal fall to early August.
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