Severely scorched leaves fall, leaving tufts of leaves at branch ends. Branch dieback occurs. This disease has been identified in Virginia, Maryland, Pennsylvania, New Jersey, and New York City. Xylella pathogenic on mulberry is also pathogenic on sycamore and vice versa. Nymph and adult spittlebugs and leafhoppers are known to be very efficient in carrying Xylella from plant to plant.
Treehoppers also are carriers.
Once the bacteria are picked up, they are in some cases immediately transmittable or, in other cases, have a 2 hr. latent period before they are transmittable. The insect will continue to carry the bacteria until it molts. Although the symptoms seem distinctive, it is difficult to be certain of the cause of a marginal leaf burn. Commercial diagnostic services can confirm the presence of Xylella . The bacteria may be so widespread in the wild plant population that removal of infected trees may not prevent the spread of the bacteria to neighboring trees.