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Cytospora Canker



P_cytosporacnkr

Cytospora Canker

Usually appear in

Spring to Autumn.


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Caused By:-     The Fungus Leucostoma persoonii

Description

Cytospora canker is a fungus disease caused by the fungus Leucostoma persoonii. It affects many different types of trees like aspen, poplar, elm, willow, ash, mountain ash, oak, apple, spruce and stone fruits (e.g., cherry, plum, and peach) and can cause branches or the entire tree to be killed. In some literature it is also known as perennial canker, peach canker, Cytospora canker, and Valsa canker. The disease is most damaging to young orchards, where it may cause tree death. In older orchards, trees gradually lose productivity and slowly decline as individual limbs are killed. The fungus attacks the woody parts of the trees through any injury to the bark, pruning cuts, and dead shoots and buds. The first visible symptom is the exudation of gum at the point of infection. The canker starts from a small center that slowly enlarges, more along the length than the width, eventually girdling the branch with the collapse of the inner bark tissue and the dying back of branches. The older cankers are therefore oval to long and are surrounded by callus tissue which is the tree's defence mechanism against attack by various fungi. Each year the canker enlarges by repeated invasion of healthy tissue. The fungus overwinters in cankers and dead twigs. Small black fruiting bodies containing spores of the fungus are produced on the smooth bark covering diseased areas on dead wood. These spores are washed from the fruiting structures during wet weather. The fungus cannot penetrate healthy bark or buds, but injured buds, bark damage are the most important sites of infection.
See these other Cankers Apple and Pear, Bacterial, Bleeding, Canker, European, Horse Chestnut Bleeding, Mulberry, Parsnip, Pear and Apple, Phomopsis, Poplar Bacterial, Rose Stem and Dieback, Willow Black, Sawflies.


Control

The best control method is to keep the tree in a healthy and vigorous condition by providing water when necessary, correct fertilising as needed and proper and timely pruning during the dormant season, as the fungus is not actively spreading and it is less likely to infect fresh pruning wounds on the tree. The cutting tools used should be sterilised before and after each cut even during the dormant season. Use a chlorine bleach and water mixture to sterilise the tools, a 1 part bleach to 9 parts water ratio.
In the growing season remove and destroy as soon as possible, preferably by burning, infected limbs or in severe cases the entire tree.
The spores of the fungus can enter and develop easily in various bark wounds on the trees.

P_cytosporacnkr P_cytosporacnkr[2]

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