continuing on with our pests and disease topic we will look at powdery mildew, this is a common problem in places with high humidity and can be caused with watering.
Powdery mildew is one of the most common and easily recognized plant diseases. Almost no type of plant is immune, however some are more susceptible than others.
As the name implies, powdery mildew looks like powdery splotches of white or gray, on the leaves and stems of plants. There are actually several types of powdery mildew fungi, but they all look basically the same. You may not notice a problem until the top surfaces of the leaves turn powdery, but powdery mildew can also affect the lower leaf surface, stems, flowers, buds and even the fruit.
Although powdery mildew is unattractive, it is rarely fatal. However it does stress the plant and severe or repetitive infections will weaken the plant. If enough of the leaf surface becomes covered with powdery mildew, photosynthesis is impaired. Infected leaves often fall prematurely. This can be a particular problem on edible crops, since insufficient photosynthesis can diminish the flavor of the fruit or vegetable. If buds become infected, they may not open and mature at all.
Powdery mildew fungi seem to be everywhere. They overwinter in plant debris begin producing spores in the spring. These spores are carried to your plants by wind, insects and splashing water. Conditions that encourage the growth and spread of powdery mildew include:
Dampness or high humidity (Not common during rainy seasons or in extreme heat)
Crowded plantings
Poor air circulation
control
Choose healthy plants and keep they growing healthy, Try and find a powdery mildew resistant cultivar, if your area is susceptible,Don’t plant non-resistant varieties in the shade.
Remove and destroy all infected plant parts
Improve air circulation by thinning and pruning
Don’t fertilize until the problem is corrected. Powdery mildew favors young, succulent growth
Don’t water plants from above, aim for the base of the tree around the soil keeping it away from the foliage
a fungicide can also be used but i would use that as a last resort as this problem can be remidied quite easily by doing the above mentioned, only use a safe fungicide as a last resort.
feel free to add anything to this thread, all experiences are welcomed, the more info we can get on these problems the easier it will be to go directly to a thread and find relevant info to the problem
jamie
this information has been sourced from various site on the internet.
taking the top half of trees of since 2005! 
