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Quince Powdery Mildew



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Quince Powdery Mildew

Usually appear in

Spring to Autumn.


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Caused By:-     The Fungus Podosphaera leucotricha

Description

Powdery Mildew on Corgette.
Quince Powdery mildew is caused by the fungus Podosphaera leucotricha and also infects apples, pears, and other fruit trees. This fungus is found in nearly all parts of the world where these fruits are grown are grown.
New leaves and shoots are more susceptible to infections than older leaves. When the buds open in the spring, the fungus grows on emerging leaves, shoots and blossoms.
The fungal mycelium initially grows on the surface of plant tissue, then root-like feeding organs called "haustoria" burrow into the leaf tissues to acquire nutrients. Later spores(conidia) are produced which the wind and splashing rain carry to other parts of the same and to other trees. Spores germinate at temperatures between 18 to 27 degrees Centigrade when relative humidity is greater than 90%. Unlike other diseases caused by fungi, leaf wetting is not necessary for powdery mildew infections. Spores will not germinate in freestanding water.
Once established, the fungus continues to grow, regardless of moisture or humidity. At the start of the infection it first shows as small greyish or white felt-like patches of fungus growth, which enlarges in time to completely cover the infected part.
Powdery mildews are one of the most widespread plant diseases. They affect virtually all kinds of plants from cereals and grasses, to fruit trees, and broad-leaved shade trees.
Powdery mildews are usually host specific, which means they do not spread to other types of plants. There are many types of Powdery Mildew fungi and they all produce similar symptoms on stems, leaves and buds. Infected leaves may become distorted, turn yellow with patches of green, and fall prematurely, stems and twigs may collapse and die and infected buds may fail to open.
The disease is usually observed on the upper sides of the leaves with a whitish fungal growth developing on the leaf surfaces in patches which eventually coalesce to cover the leaves, stems or buds which kills the leaves flowers or shoots.
The severity of the disease depends on several factors such as variety of the host plant, age and condition of the plant, and is especially severe in warm, dry climates. This is because the fungus does not need the presence of water on the leaf surface to infect it. However, if the relative humidity is high the problem will be worse. Therefore, Crowded plantings where air circulation is poor damp and in shaded areas makes the problem worse. Young growth usually is more susceptible than older plant tissues.
See also these other Powdery Mildews Apple, Begonia, Hydrangea, Oak, Pansy, Pea, Phlox, Powdery, Rose.
See also Downy Mildews Brassica, Downy, Hebe, Lettuce, Onion, Pansy, Pea.
See also other Mildews American Gooseberry, European Gooseberry, Gooseberry.


Control

The best method of control is prevention therefore good hygiene and cultural practices are essential to avoid this disease.
Raking up fallen leaves, placing plants in full sun with pruning that allows good airflow through the plant, Winter tar, oil or fungicide wash and pruning out severely infected branches and burning them will all help in preventing attack from these fungi.
Fungicides are often ineffective and special systemic fungicides will have to be used.
A weekly spray of milk at a concentration of at least 10% (1 part milk to 9 parts water) is said to significantly reduced the severity of powdery mildew infection.
Weekly preventative sprays of baking soda( 1 tablespoon of baking soda a few drops of washing up liquid to 1 Gallon of water) makes an inexpensive control for powdery mildew on plants. Once the infection has taken hold baking soda offers only minimal benefits.
Some plants can be burnt by the baking soda therefore test before use on specific plants.
Spraying with a mixture of baking soda(sodium bicarbonate) or potassium bicarbonate combined with a lightweight horticultural oil is said to cure and prevent the problem.
Mulching the plants should help in preventing many Powdery Mildews which prefer dry conditions.



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