Symptoms:
Ca. Phytoplasma prunorum is associated with ESFY disease, which primarily includes diseases of apricot, Japanese plum, and peach.
Symptoms of ESFY are influenced by species, cultivar, root stock, and environmental factors. There are many tolerant hosts that do not show any symptoms of disease but can harbor infections.
Apricot and Japanese plum trees in general show typical 'yellows' symptoms accompanied by leaf roll, followed by leaf reddening, reduction, or suppression of dormancy with the consequent risk of frost damage, severe and progressive necrosis, decline, and eventual death of the tree. Peaches exhibit early leaf reddening, severe upward longitudinal rolling of leaves, abnormal thickening and suberization of the midribs and primary veins, autumnal growth of latent buds which produce tiny chlorotic leaves and sometimes flowers, and early leaf fall. The leaves also tend to be 'more brittle' than normal.
ESFY affects tree flowers and shoots in winter, which leads to lack of fruit production and chlorosis of the leaves later in the growing season. The early break in dormancy increases the susceptibility of affected trees to frost, which can cause damage to the phloem. Disease often starts with only a few branches affected but the whole tree may become affected as the disease progresses. Infected shoots are typically shorter and bear smaller, deformed leaves. Leaves can drop prematurely. Shoots may die back. Yield is reduced. Fruit on affected branches develops poorly and may fall prematurely.