Issue 11, September 13, 2019

Hackberry Island Chlorosis

Island Chlorosis is a common disease of hackberry. While I am never surprised to see this disease, its occurrence seems to be a bit more noticeable this year. Symptoms appear as a rather interesting blocky mosaic pattern of yellow, cream, and light green spots intermixed with healthy green tissues. The lesions are delineated by veins, giving them an angular appearance.

Hackberry island chlorosis was initially suspected to be the result of a phytoplasma, virus, or possibly a physiological abnormality. My most recent search of published journals turned up little information on this disease. The strongest result was an abstract for a presentation by Benham Lockhart, a professor of plant pathology at University of Minnesota. That abstract linked disease symptoms to a previously undescribed virus. Unfortunately, no additional publications were available on this virus. While it may seem surprising that so little research has been done on such a noticeable disease, it’s likely due to the fact that it doesn’t seem to harm the tree’s health.

No controls chemical controls are available, or warranted. Instead, focus efforts on practices that encourage the tree’s vitality, such as watering during drought, fertilizing as needed and proper pruning.

Travis Cleveland

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