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Gladiolus Rust



P_gladrust

Gladiolus Rust

Usually appear in

Spring to Autumn


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Caused By:-     The Fungus Uromyces transversalis

Description

Gladiolus Rust is caused by the fungus Uromyces transversalis and is an obligate parasite that only grows and reproduces on members of the family Iridaceae, including Gladiolus, Tritonia, Crocosmia and Watsonia spp. It primarily attacks hybrid cultivars of gladiolus grown for cut flower production, and if uncontrolled, can lead to total yield losses.
Initially, small yellow spots appear on the leaves followed by orange rust pustules formed when rust spores emerge through the surface of the leaf. Later in the year black pustules that contain teliospores or resting spores eventually surround these initial orange pustules. The eruption of spores progress transversally across the width of the leaves and may be up to 3 mm long each, typically elongated across the width of the leaves.
Infection of gladiolus plants is most severe when temperatures are between 10 and 20°C and leaves remain wet for at least 12 hours. Severely damaged plants do not flower and/or their corms do not ripen. The disease is serious in nurseries and can completely destroy commercial gladiolus crops unless fungicides are used.
GR is indigenous to southern Africa, where it was first noted on leaves of Tritonia securigera in 1876. This fungus is a disease of quarantine interest in some countries.
See also UROMYCES,
See also these other rusts Anemone, Antirrhinum, Bean, Bluebelle, Broad Bean, Cedar Quince, Chrysanthemum White, Fucshia, Gooseberry, Hollyhock, Juniper Pear, Mahonia, Mint, Pear Juniper, Pelargonium, Periwinkle, Plum, Potato Internal, Quince, Rhododendron, Rose, Rust, White.


Control

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.
Spraying with a suitable fungicide is necessary and must be carried out several times.
As with any fungal disease one of the best ways of preventing it is by good hygiene. Remove 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 and remove 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.
Maintain an open structure to allow good air circulation through the plant and ensure greenhouses are always well ventilated. Rotate bean with non-host crops.
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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