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European Gooseberry Mildew



P_eurogsbrymldew

European Gooseberry Mildew

Usually appear in

Spring to Autumn.


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Caused By:-     The Fungus Microsphaera grossulariae

Description

There are two mildew that affects gooseberries and related plants as well as Botritis fungus. One is the European(Microsphaera grossulariae) and the other is the American(Sphaerotheca mors-uvae). European Gooseberry Mildew is not considered as a serious disease and rarely does huge damage to gooseberries. It is a white epiphytic mildew that appears on the leaves, but rarely on to the fruit. It grows both above and below the leaves, and forms a very thin white layer. A short time later small round fruiting bodies containing conidia(asexual spores) are produced which makes the leaf surfaces looks like it was sprinkled with flour. Later in the year small black fruiting bodies(perithecia) containing sexual spores appear with the white fruiting bodies. These are the winter forms which remain on the fallen leaves to re-infect new leaves the following year.
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.
Mildews are generally host specific, which means they do not spread to other types of plants. There are many types of 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 all over the leaves and shoots with a whitish fungal growth developing on the leaf surfaces in patches which eventually kills the 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 cool wet climates. The fungus needs a certain period of wetness on the leaves 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.
Picture by Petr Kapitola, State Phytosanitary Administration, Bugwood.org.
See also other Mildews American Gooseberry, Gooseberry.
See also these other Powdery Mildews Apple, Begonia, Hydrangea, Oak, Pansy, Pea, Phlox, Powdery, Quince, Rose.
See also Downy Mildews Brassica, Downy, Hebe, Lettuce, Onion, Pansy, Pea.


Control

This fungus is encouraged by stagnant air around the branches and by excessive use of high nitrogen fertilisers which will only generate soft new growth that's prone to infection. Therefore keep the growth of the plants as open as possible allowing a good airflow through the plants. When planting new bushes, choose an open, sunny spot and do not overcrowd them.
Cut out and burn infected shoots. This fungus overwinters on the branches and in the buds therefore a winter spray wash is helpful.
Potassium sulphide used at a ratio of 60g to two gallons of water and repeated every ten days until the fruit is nearly mature is said to be much more effective as a fungicide than many other propriety fungicides.
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.
Keep the soil around the roots moist by the use of a mulch. When planting new bushes, choose an open, sunny spot and do not overcrowd them.
The spores are wind blown as will as water splashes.
There are resistant varieties of gooseberry that can be grown.
Spray as soon as it is seen which usually stops the infection.
This fungus overwinters on the fallen leaves so good hygiene, by raking up fallen leaves, will usually prevent this disease. Dry conditions may make this disease more capable of attacking gooseberries therefore keep the soil around the roots moist by the use of a mulch.
The asexual spores are wind blown as will as water splashes. There are resistant varieties of gooseberry that can be grown.



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