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Black knot occurs only on the woody parts of trees, primarily on twigs and branches, but can spread to larger limbs and even the trunk. Olive-green swellings from the disease are visible in the late spring; as it spreads and matures, typically by autumn, rough black knots circle and kill affected parts. The knots vary in diameter from one inch ...
Brachycaudus helichrysi is a serious pest of stone fruits. It forms dense colonies on the underside of the leaves of the primary host causing curling, [4] twisting and distortion of the foliage, the shedding of flowers and the dropping of young fruit. [8] It is one of several species of aphid that can transmit the virus that causes plum pox. [8]
Viral diseases; Bare twig and unfruitfulness genus Nepovirus, Strawberry latent ringspot virus. genus Tobamovirus, Cucumber green mottle mosaic virus. Line pattern & Necrotic ring spot genus Ilarvirus, Prunus necrotic ringspot virus (PNRSV) Peach mosaic genus Trichovirus, Cherry mottle leaf virus (CMLV) Plum pox (= Sharka)
Plum pox, also known as sharka, is the most devastating viral disease of stone fruit from the genus Prunus. The disease is caused by the plum pox virus (PPV), and the different strains may infect a variety of stone fruit species including peaches , apricots , plums , nectarine , almonds , and sweet and tart cherries .
In California and Idaho, it has been found on plum and prune trees. In Europe, the disease can be found on apricots, peaches, and cherries. Leucostoma canker has also been witnessed in South America and Japan. [1] The spread of disease is favored in cool, wet, and humid conditions in late fall or early spring when conidia are most abundant.
Taphrina pruni is a fungal plant pathogen of blackthorn (Prunus spinosa) that causes the pocket or bladder plum gall, a chemically induced distortion of the fruit (sloes), producing swollen on one side, [1] otherwise deformed and flattened fruit gall without a stone. [2] The twigs on infected plants may also be deformed with small strap-shaped ...
Branch knot Sphaeropsis tumefaciens: Brown rot (fruit) Phytophthora citricola Phytophthora citrophthora Phytophthora hibernalis Phytophthora nicotianae var. parasitica = Phytophthora parasitica Phytophthora palmivora Phytophthora syringae. Charcoal root rot Macrophomina phaseolina: Citrus black spot Guignardia citricarpa: Damping-off Pythium sp.
A fungus in the genus Taphrina often attacks the plums; the young ovaries swell, often much larger than full grown plums, become hollow and often persist on the tree in winter. Known as "plum pockets", they appear pale green, leathery to the touch, and hollow with the exception of a few fibrous bands. The disease reduces regeneration of the plums.