The Purdue Plant and Pest Diagnostic Laboratory

What's Hot at the P&PDL
May 23, 2013

Anthracnose and Maple Leaf Blister

Gail Ruhl, Plant Disease Diagnostician, Department of Botany & Plant Pathology, Purdue University

Cool, wet, conditions during leaf emergence this spring provided the perfect environment for foliar fungal infections on maples and other trees. This week we identified a fungal disease wreaking havoc on maple leaves that exhibits both tar spot and anthracnose look-alike symptoms (Figure 1).

The name of the disease is maple leaf blister and it is caused by one of the Taphrina fungal spp. Both anthracnose and maple leaf blister have been confirmed on the same leaves and together are causing leaf blotches and scorch-like symptoms. Interveinal scorch-like symptoms are especially severe on silver maple and may cause premature leaf drop. Thus far we have confirmed these foliar diseases on silver, sugar, red and Freeman maple.

Although maple leaf blister is a very descriptive name for this disease (Figure 2), due to the dual infection of leaf blister and anthracnose, many of the infected leaves not only possess the characteristic blisters but also symptoms that include grayish brown to black splotches and black, dead tissue between the veins as lesions coalesce (Figures 3 & 4). If premature leaf drop occurs, the leaves should be replaced by new ones within several weeks to a month, and long-term detrimental effects to the overall health of well-established trees should be minimal.

The high-risk period for infection is when leaves are young; older leaves are more resistant to fungal infection. If the environmental conditions next spring are once again cool and wet while leaves are emerging, we will likely see similar symptoms from infection

Two other diseases, leaf blister on oak caused by Taphrina caerulescens, and peach leaf curl/plum pockets, caused by Taphrina communis also commonly occur in Indiana.

BP-413-W: Leaf Diseases (pdf file) - Janna Beckerman, Purdue University


Click image to enlarge

Figure 1. Symptoms of Maple blister evident in lower canopy

Figure 2. Characteristic blisters of Maple leaf blister

Figure 3. Foliar symptoms typical of maple leaf blister and anthracnose

Figure 4. Foliar symptoms typical of maple leaf blister and anthracnose


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