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Quince Rust


Quince Rust

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Caused By:-     The Fungus Gymnosporangium clavipes


Gymnosporangium clavipes with aecia spore producing bodies on a Hawthorn(Crataegus) branch.
The Quince Rust is caused by the fungus Gymnosporangium clavipes and like most rust diseases needs two hosts to complete its life cycle. The full name of this disease is Cedar-Quince Rust. Cedar-Hawthorn Rust (G. globosum), and Cedar-Apple Rust (G juniperivirginianae) are closely related rust diseases that also require two hosts to complete their life cycle. Cedar-Quince Rust disease damages cedars(junipers), killing young branches and weakening plants and when cankers occur on the main trunk the tree dies. The fungus spends part of its annual life cycle in several broadleaf rosaceae family hosts including: Cotoneaster, Hawthorn(Crataegus), Applea(Malus), Red Robin(Photinia), Pears(Pyrus), and Mountain Ash(Sorbus), as well as the common quince (Cydonia), and flowering quince (Chaenomeles). It then spends the other part of the annual cycle in junipers such as eastern red cedar (Juniperus virginiana).
On the red cedar twigs twigs and branches infected with quince rust swell up two to three times the size of adjacent healthy branches. The fungus hibernates within the twig as mycelium. The fungus can become perennial in the cambium which eventually encircle branches of the cedar which eventually dies back to a single shoot. This rust causes flaky branch swellings which are distinctive of this fungus. Most people do not notice the branch swellings until it become wet, swell with bright orange gelatinous spores. These spores gets blown or carried to the many broadleaf trees it infects. The spores never reinfect the cedars.
Once on the quince and other broadleaf trees, the spores germinates and grow into the tissues of the fruit or twig, leaves, and petioles causing distortions and malformations, but symptoms vary widely among the various hosts. Twig-infections are commonly found at the base of new shoots, and knots are produced which resemble Black Knot of plums or cherries.
Diseased fruits are very conspicuous because the injured portion is covered wholly or in part by masses of orange tubular fringe-like growths, the whole having a yellow woolly appearance.
Finally the tubular projections develop another sort of spores which can only develop on cedar trees and cannot reinfect the quince.
More than one type of rust may be present on many of the plant hosts. Although these rusts are quite similar, only cedar-hawthorn and cedar-quince rust galls produce spores for more than one year.
Picture from Wikimedia Commons
See also these other rusts Anemone, Antirrhinum, Bean, Bluebelle, Broad Bean, Cedar Quince, Chrysanthemum White, Fucshia, Gladiolus, Gooseberry, Hollyhock, Juniper Pear, Mahonia, Mint, Pear Juniper, Periwinkle, Plum, Potato Internal, Rhododendron, Rose, Rust, White.


Monitoring rust canker on red cedar trees and temperatures during wet periods in early spring and prune out any infected twigs and branches.
The vulnerable point of attacking this fungus lies in the inability of the fungus produced on one tree to reinfect it. It must pass to the opposite host.
If there is a chance of infection spray broadleaf plants with a fungicide preferably a systemic one. Rust lesions appear on fruit within two to four weeks after infection.
Grow resistant varieties, but some cultivars that are resistant to cedar-apple rust are susceptible to quince rust and vice versa. The most direct method of control is to exterminate cedars near the orchards or vice versa. In the European Community the products permitted under organic regimes have little effect rusts. Fungicides containing myclobutanil (Bayer Garden Systhane Fungus Fighter and other formulations), penconazole (Westland Fungus Attack) and triticonazole (Scotts Fungus Clear Ultra) can be used to control rust, but care should be excercised when using these fungicides.
The fungus is encouraged by high humidity with a lack of air circulation. In greenhouses it is best to keep air circulation high and conditions on the drier side.
It overwinters on old plant materials so these should be burnt.
As with any fungal disease one of the best ways of preventing it is by good hygiene. Remove and burn all dead leaves in autumn to prevent the spores from over wintering. If the leaves is from an infected plant burn them.
Water the compost of susceptible plants directly trying not to wet the foliage as the rust needs a period of leaf wetness to germinate and infect.
Watering the soil in the dormant season with Jays fluid or Amarillotox should also help. In some Countries these products are not licensed for this use.
Maintain an open structure to allow good air circulation through the plant and ensure greenhouses are always well ventilated. Often there are resistant varieties of the plant you wish to grow.
Avoid over application of nitrogen, which produces soft growth which is more susceptible and ensure adequate potassium fertiliser.

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