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Rose Stem Canker and Dieback



P_rosestckrdbk

Rose Stem Canker and Dieback

Usually appear in

All Year


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Caused By:-     Various Fungi

Description

There are several fungi that cause Rose Stem Canker and dieback. The most prevalent is Coniothyrium wernsdorffiae and others are Coniothrium fuckelii(Diaplella coniothyrium), Cryptosporella umbrina(Diaporthe umbrina), Phomopsis, Coniothyrium and Alternaría. The symptoms are slightly varied, but similar.
Usually the cankers start as small yellowish or reddish spots on the bark, which gradually increases in size. Eventually it turns brown, increases in size, and may eventually girdle the cane. The tissue within the canker begins to dry out and shrink, giving it a slightly sunken appearance. If the canker only covers part of the cane, the growth above the canker will continue, but if it girdles the cane the growth above the canker will die back.
Sometimes small black specks, which are spore forming structures producing spores, can be seen on the cane surface within the cankered area.
Although the disease is mostly on outdoor rose stems, infections can also occur on the leaves and flowers with spots ranging from purple to buff or are grayish white with a purple margin.
The fungi usually enters the plant at a wound caused by branches rubbing or pruning damage, but if the rose is growing healthily this disease should not be able to infect your roses.
The fungi are most active during the late Autumn, Winter and early Spring when roses are not actively growing.
If the rose tree is already weakened by black spot, or other disease, it is more susceptible to being infected.
See these other Cankers Apple and Pear, Bacterial, Bleeding, Canker, Cytospora, European, Horse Chestnut Bleeding, Mulberry, Parsnip, Pear and Apple, Phomopsis, Poplar Bacterial, Willow Black.


Control

Ensuring vigorous growth and removal of dead canes and stubs will help to reduce the primary source of the fungi spores.
Controlling Stem Canker is a combination of good sanitation, like raking up and destroying infected leaves and other dead plant materials and sterilisation of pruning utensils between different roses, proper pruning procedures, like making sure branches do not rub against each other, and the appropriate use of fungicides, like spraying on a regular basis.
Spraying the canes and surrounding soil area with liquid lime-sulfur during the resting period and again before, not after, bud break will control these fungi as well as other diseases.
Add 1 part of liquid lime-sulfur to 9 parts of water (do not mix with other fungicides or expose to freezing). Lime-sulfur is caustic and will discolour paint.



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