grevillea are small to intermediate sized evergreen shrubs that get a wide of the mark variety of heyday shapes and color , count on the species . These Australian plant are popular with gardener because they bloom quickly and need footling upkeep , away from pruning . They also attract birds and do n’t usually have problem with disease . However , there are a few fungal disease that can infect them .
Leaf Spots/Blights
Grevilleas can become infected with cercospora and phyllostica , two fungal disease that favor humid circumstance . Symptoms of phyllosticta include previous yellowing of foliage and the appearing of pear-shaped or atypical gray-headed , chocolate-brown or black spot . Some smudge may exit holes in the leaf when they send away out . little , black fruiting body can be come across in the erstwhile spots . Leaves on cercospora - infect plants turn bronze or abstemious brown , then gray with fuzzy spore - bearing fruiting bodies . Cercospora ordinarily attacks the inside leave first and , finally , as the dead leaf drop , the only leaves lead are those at the tips of the subdivision . Fungicides are n’t usually needed for phyllosticta contagion , but are useable for treating cercospora .
Armillaria
Armillaria root hogwash can be a trouble for grevilleas develop on poorly - enfeeble grime . seem for creamy white MAT of fungous growth between the bark and Mrs. Henry Wood , and blackened threadlike structures on the roots . Fungal mats can usually be find just above the soil course . In addition , honey - colour mushrooms may grow around the base of the shrub in the dip . Above terra firma symptom let in discolored leaves and limb dieback . Armillaria can kill grevillea shrub in less than two years . Fungicides are ineffective . If the disease is caught early enough , expose the root shoe collar to line for several month over the growing season can slow down it down .
Phytophthora
Phytopthera cinnamomi , or cinnamon fungus , is another disease that can kill your grevillea . plant growing in soggy dirt for extended full point of meter are particularly susceptible . Symptoms include wilting and leafage that twist yellow , red or purplish in coloring . Look for ruddy brown streaks in the woodwind instrument under the barque . youthful Tree are more apt to pass away because of the small size of their origin organization . forestall phytophthora attacks by providing shrubs with in force drainage and not allowing them to stand in water supply . head off wetting the trunk and lower outgrowth . The fungicide fosetyl - Al can be used to help prevent infections , but does n’t replace unspoilt cultural exercise .
Sooty Mold
Sooty mold form a gray to fateful velvety or crusty fungal coating on the leaves , but rubbing the leaf between your finger will dispatch the clay sculpture . Sooty mould is an aesthetic problem and does n’t bolt down shrub , although serious infections may interpose with a plant ’s ability to do photosynthesis . Sooty mold often grows on plants that are infested by insect like aphids or scale . These insects secrete a mellifluous , sticky substance yell honeydew that attracts pitchy mold . hold in this fungus by manipulate the worm overrun your works . Sooty mold can be take from leafage by wash out it off with a strong spray of water system .
