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Mint Rust


Mint Rust

Usually appear in

Spring to Autumn.

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Caused By:-     The Fungus Puccinia menthae


Mint rust is a common fungal disease of garden mint, which also affects other herbs like marjoram and savory. The fungus causes vivid dusty orange spores, which later fades to brownish/black resting spores, on the underside of the leaves. The top side of the leaves where the spores are grouped is chlorotic and eventually dies leaving a spotty leaf. The stems may also contain cup like fungal spores, which makes the stems twist and distort before eventually dying. The rust fungi grows within the living tissues of the plant and extract nutrients from the cells. It also invades the rhizomes where it can spend the winter. The fungus cannot exist in dead plant material, but before the leaves dies it would have produce spores which can re-infect the plant in the following year.
See also these other rusts Anemone, Bean, Bluebelle, Cedar Quince, Chrysanthemum White, Fucshia, Gladiolus, Gooseberry, Hollyhock, Juniper Pear, Mahonia, Pear Juniper, Pelargonium, Periwinkle, Plum, Potato Internal, Quince, Rhododendron, Rose, Rust, White.


Remove the infected plants along with its rhizomes as soon as the fungus is seen hopefully before the resting spores are produced. Spraying with a systemic fungicide should control the fungus, but it will have to be regularly repeated to keep the fungus at bay. In the winter a soil sterilant such as Jays Fluid or Amarillotox could be used to help kill off the spores. These two substances are not licenced to be used in the European Union as the firms cannot pay the high price of obtaining a licence. A heat treatment method is possible where the rhizomes are washed in hot water at 44C (111F) for ten minutes, but care must be used at this temperature is near the lethal temperature of the plant.

P_mintrust P_mintrust[2]

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