Symptoms. Powdery mildew of apple produces symptoms on young shoots, leaves, blossoms, and fruit. Eventually, we realised that both trees had powdery mildew. The disease causes economic damage by reducing tree vigor, flower bud production, and fruit quality. At the time, we noticed that some of the apple trees they had in stock also had powdery mildew. But despite the name, it is not only one of the most serious diseases of Apple tree, but also of Pear, Quince, and of Peach tree – from stone fruit crops.. We mentioned this, and the chap just mumbled something about having had a wet winter and that it was just "one of those things". Infected leaves become covered with a white to gray powdery growth, usually on the upper surface; unopened flower buds may be white with mildew and may never open. Apple powdery mildew – additional information Disease status. The fruits are rarely affected, but so much foliage can be destroyed that the tree's vigour, and consequently next year's crops, could be reduced. Q What is apple powdery mildew?. Powdery mildew starts on young leaves as raised blister-like areas that cause leaves to curl, exposing the lower leaf surface. Powdery mildew on tomato plants often begins with pale yellow leaf spots that develop into the typical white, powdery growth. Experts do agree, however, that is does work. Powdery mildew can negatively impact photosynthesis, shoot growth, and reduce fruit set. Symptoms and Signs. Powdery mildew is one of the most important diseases of apple in the UK. The JG moreso than the Braeburn. A It’s a very common fungal disease which turns the young shoots of apple trees white. Powdery mildew of apple occurs in all apple-producing regions of the world. Leaves of severely infected plants turn brown and drop. Keep trees clean and uncrowded. Pears may also suffer powdery mildew attacks, which should be dealt with in the same way. The Apple Powdery Mildew, which is caused by the ascomycete fungus Podosphaera leucotricha, represents an important disease of the tree and crop.. Powdery mildew affects many plants, from roses to green beans. To treat powdery mildew with milk, mix 1 part milk to 2-3 parts water. As resistance to certain fungicides becomes more common integrated management with good resistance management is critical. Milk Treatment. Milk is one of the best organic powdery mildew treatments. Apple powdery mildew is becoming more problematic as many cultivars preferred by consumers are powdery mildew susceptible. All parts of the tree are affected, including fruits and it reduces yield and quality and repeated severe attacks gradually debilitate the tree. Types of Plants Affected With the exception of gymnosperms, such as conifers, most of your plants are at risk of a powdery mildew infection if the conditions are right. Prevention is key to controlling powdery mildew, but there are also organic measures you can take to stop infestations on your apple or other fruit trees. It is believed that the proteins in milk act like an antibiotic when exposed to sunlight, but more research needs to be done as to why it works.