Leaf and Shoot Blight

Encyclopedia Article

Overview of leaf and shoot blight

The fungus overwinters in infected shoots. Fungal spores are splashed by rain from shoots blighted the previous season to the newly emerging shoots and leaves. Trees in crowded plantings are more often severely diseased than those planted on wider spacings. Disease severity differs among hybrids.

Image of a poplar leaf with a case of Venturia blight
Poplar leaf with a case of Venturia blight 

Signs and symptoms of leaf and shoot blight  

Leaf symptoms are evident in May. Irregular brown or black spots form, causing leaves to appear deformed. Infected shoots turn black, brittle, and bend over to resemble a shepherd's crook. Only young shoots and leaves are susceptible. As the season progresses and tissues mature, they become resistant.

Death of shoots reduces height growth and can deform small trees by causing bends in the stems. Repeated attacks by the fungus can weaken trees and allow attack by other organisms.

Disease cycle of leaf and shoot blight

The fungus overwinters in infected shoots. Fungal spores are splashed by rain from shoots blighted the previous season to the newly emerging shoots and leaves. Trees in crowded plantings are more often severely diseased than those planted on wider spacings. Disease severity differs among hybrids.

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant and Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant and Insect Diagnostic Clinic without contacting us

Management of leaf and shoot blight

Although fungicides are available for leaf disease control on poplar, none are labeled specifically for this disease. If feasible, it may be helpful to remove blighted shoots, pruning at a junction well below the margin between healthy and diseased tissue. Trees less than 10 feet tall are at greatest risk. Once trees are over 15 feet in height the damage becomes negligible. 

 

 

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