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Rose Rust


Rose Rust

Usually appear in

Spring to Autumn.

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Caused By:-     The Fungus Phragmidium tuberculatum


Rose rust is caused by the fungus Phragmidium tuberculatum and some other Phragmidium related species. Unlike most Rust, which have two hosts and each host produces spores that can only infect the other host, Rose Rust produces overwintering spores in the Autumn and only attack roses. It infects the host tissues feeding on the living cells.
It appears in spring and unless treated, persists until the leaves yellow and fall. In late summer, the orange pustules turn black which are the overwintering spores.
The symptoms are yellow spots on the upper surfaces of the leaves which corresponds to pustules of dusty orange spores on the lower surface. Infected leaves tend to fall early.
The over wintering spores can survive on fallen leaves and on the soil surface.
Spores from the pustules can be transmitted between plants by the wind, on animals, insects or people's clothes.
It is encouraged by a humid, moist conditions.
Susceptibility to rust varies widely among rose cultivars, and most modern roses should be resistant to rust.
Picture by Cesar Calderon, USDA APHIS PPQ,
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, Pelargonium, Periwinkle, Plum, Potato Internal, Rust, Quince, Rhododendron, White.


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.
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.
Check plants regularly, remove and burn infected leaves by hand as soon as they are seen and then spray with a suitable fungicide. Spray the plant and the soil around it with a fungicide suitable for the control of rust fungus.
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.
Susceptibility to rust varies widely among rose cultivars, and most modern roses should be resistant to rust.

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