Powdery mildew is a fungal disease affecting a wide range of plants. It can be recognised by the characteristic dusty, white coating on leaves and stems.
DAMAGE: Powdery mildew causes the upper surface of the leaves to be covered with a white powder, which is actually made up of the fungal spores. Leaves affected by mildew can fail to develop normally and fall prematurely. In some cases blossom can also be affected.
TREATMENT: Gathering fallen leaves and fruit and removing from site in the Autumn can help reduce the amount of infectious spores. Promptly pruning out infected shoots can help reduce subsequent infection. An application of SB Invigorator can help reduce fungal diseases. Pruning to keep an open canopy and improving air circulation will be very beneficial.
MANAGE THE SOIL: Provide good drainage and water regularly as required. Trees that are allowed to dry out and then watered can be more susceptible. Mulching can also help conserve moisture as well as feeding the tree and helping to reduce the growth of weeds etc,.
HOW ARE DISEASES SPREAD?
Most fungal infections are carried by spores being blown, from one plant to another by the wind, or transmitted in water splashes. Bacterial infections are spread in the same way although insects can also carry them. Viruses are transmitted by sap-feeding insects, especially aphids.
PREVENTING DISEASE Plants are most at risk when they have just been pruned or are damaged. It is imperative to prune at the correct time of the year – Winter season (when the tree is dormant (lost all of it’s leaves)) for fruits with a pip; apples, pears and quinces. Growing season (July/August even if fruit is on the tree) for stone fruits; apricots, cherries, gages, nectarines, peaches and plums.
Do not overcrowd trees Make sure they are planted with sufficient space between. Free-standing trees should not be planted near fences/walls/buildings etc.
Weed, water and feed your trees Especially through dry spells. The healthier your tree is the more resistant to infection and disease it will be.
Disinfect tools Before and after use, especially when pruning.
Dispose of infected matter Clear all windfalls, pruning and any infected/diseased leaves. Burn or remove from site rather than composting.