P&PDL Picture of the Week for
June 16, 2008

Peach Leaf Curl and Oak Leaf Blister: Taphrina strikes again

Tom Creswell, Plant Disease Diagnostician and Director, PPDL

Each year around late May or early June we see leaves of peach, plum and oak start to show distortion, cupping and blister like growths. These abnormal areas usually start out pale green or perhaps tinged pink or purple, but over the course of 2-3 weeks they turn dark and necrotic. The cause? A fungus known as Taphrina sp. This fungus is also known to infect Maple, Beach, Hop Hornbeam, Poplar, Sumac, American Elm, Hazelnut and Alder.

On oak the problem is known as oak leaf blister and it’s a minor issue on trees that are healthy otherwise. It may cause some leaf drop but won’t seriously harm the tree.

It’s called peach leaf curl on peach, and plum pockets when seen on plum fruit. These infections happen sporadically in home plantings and are rarely a significant problem in orchards that are routinely sprayed for other fungal problems. On non-sprayed stone-fruit trees it may cause leaf drop, minor twig death and weaken the tree, making them less resistant to other problems. By the time the symptoms show up in the spring it is too late to spray for this disease.

Spores overwinter on leaf buds and infect leaves as they open. Only one infection cycle occurs each season, and mature leaves become resistant to infection. Cool and rainy spring conditions favor infection. No control is needed on most ornamental trees since the disease is brief and causes no real harm. Plants in the nursery may need to be sprayed to keep them in good shape for sales.

Spores spend the winter on leaf buds and infect leaves as they open in the spring. Because of this there is little value in cultural controls like raking and getting rid of infected leaves.

The following websites offer more information on this group of diseases:

Click image to enlarge

Oak Leaf Blister

Oak Leaf Blister

Peach Leaf Curl

Peach Leaf Curl

Peach Leaf Curl

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service