The hydrangea is a deciduous bush characterized by its blossoms and green leafage . The most mutual hydrangea is the bigleaf hydrangea , which is native to Japan . There are three common fungi that attack the hydrangea leaves : powdery mildew , genus Cercospora leaf place and anthraconose .

Powdery Mildew

Powdery mildew disease is find out largely in commercial-grade glasshouse , attacking a number of hydrangea cultivars ; they are then unable to deal these diseased plants . When powdery mildew attacks hydrangeas in the landscape , the symptoms are a powdery / white covering on the underside of the leaves , with the topside of the leaf turning purplish - brown ( the topside of the folio can also stay on green ) . You may also see the powdery mildew on buds and novel ontogenesis .

Treating Powdery Mildew

You will need to use a wettable garden sulphur fungicide , follow the manufacturing business ’s practical program directions . Generally , the antifungal is applied as soon as you see the powdery snowy coating . You must also ensure to dispose of all of the leaves / utter industrial plant material in the declination so that the pathologic material does not overwinter beneath the plant . It is also a good drill to mulch the plant . Mulch helps to keep the spore of the fungus from being splashed back up on leaf . Some enquiry has been done on the economic consumption of anti - transpirant spraying and their ability to help plants that can be capable to mold resist infection . In theory , the nebulizer coat the leaves and produce it harder for the mold spores to adhere to the leaves when it rains .

Cercospora Leaf Spot

Cercospora leaf spot is qualify by small , disordered brown or purple spots on the farewell that are locate close to the fundament of the plant . spot generally start in midsummer and becomes prominent in early surrender . This disease induce the leaves to fall off of the plant prematurely , and it will affect the number of flowers , as well as the overall appearance and vigor of the plant . The disease is spread by spore from the fall leaves . These spore remain on the ground and are easily scatter to healthy leaf by splashing water system / rainwater .

Treating Cercospora Leaf Spot

Remove the diseased leafage and apply a fungicide that is recommended for cercospora foliage spot ( following the maker ’s program directions ) . Look for products that contain the one of the play along fighting ingredients : azoxystrobin , chlorothalonil , mancozeb , myclobutanil , and thiophanate - methyl . These ingredients are used in healing systemic fungicide product . The antifungal should be go for as soon as you notice the disease . You may require to do several applications of the fungicide .

Anthracnose

Anthracnose attack the leaf and also the heyday . The fungus thrives in red-hot , wet weather and on hydrangea that are heavily fertilized . Anthracnose is qualify by pear-shaped , more or less maverick brown spots on the folio and flowers . The spots appear stump or sunken . Spots can be as large as an inch in diameter and look like a bull’s - heart . They will appear on the base of the plant as well as the top of the plant , on both leaves and flowers .

Treating Anthracnose

Treatment is the same as with cecospora ; pathologic leaves will need to be removed and a antimycotic should be applied . you may habituate chlorothalonil or thiophanate - methyl ( following the manufacturer ’s coating directions ) .

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