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Peach Leaf Curl

Fungus affects peaches & nectarines

By: Sandy Feather 2014
Penn State Extension


Q. I planted a peach tree several years ago. It has grown well, but this year there is something wrong with the leaves. They are puckered up and curled, and generally malformed. Most of them dropped through the growing season. I have looked carefully at the leaves and examined them for insects, but I do not see anything. Can you tell me what is wrong? Is this going to kill the tree?

A. Your description is consistent with a common fungal disease known as peach leaf curl that affects peaches and nectarines. The leaves become infected in early spring as soon as the buds begin to open. Spores of the causal fungus (Taphrina deformans) overwinter on the bark and twigs. Rain splashes the spores onto the buds, and the leaves are infected as soon as they begin to unfurl. This disease is exacerbated by the cool, wet spring weather we experienced this year.

 

peach

Dry spring weather actually inhibits the development of this disease because wetness is necessary for infection to occur. As the season progresses, infected leaves become covered with a grayish-white powder. These are the spores of the causal fungus. Infected leaves shrivel and drop prematurely. The powdery spores are blown back onto the bark and twigs where they spend the winter.


Disease Weakens Peach Trees

Although leaf curl does not kill a tree outright, it does weaken a tree to lose its leaves so early in the summer. That means that the tree did not have much of a chance to produce carbohydrates through photosynthesis. Those stored carbohydrates are important to help a tree withstand stress from drought, insect or disease problems as well as providing the energy for it to push out new growth next spring. Trees that are defoliated in early summer often try to flush out a second set of leaves, which further depletes their store of carbohydrates. Trees that are defoliated by peach leaf curl in successive years can die.


Peach Leaf Curl Prevention

To prevent leaf curl from infecting your tree next spring, wait until the leaves drop in the fall and the tree is dormant, and then apply a lime sulfur spray.

Spray on lime sulfur spray

Make another application next spring just as the buds begin to swell, but before they open. Spray the trunk, branches and twigs thoroughly, to the point of runoff. If the tree responds well next year, you need only make a single application in the fall, once the leaves drop and the tree is dormant.


Cultural Practices

Cultural practices that maintain the tree's vigor are also important. These include:

Thin the fruit when they are one-half inch in diameter so that you leave one fruit every six to eight inches. This results in larger fruit for you and less demand for nutrients on the tree.

Keep the tree watered if we get into hot, dry weather. Use a soaker hose or remove the nozzle from your hose and let the water trickle slowly around the base of the tree, moving the hose every 20 - 30 minutes until you have watered thoroughly around the circumference of the tree. This should be done weekly until temperatures cool off and regular rain resumes.

10 - 10 - 10

Apply one and one-half pounds of 10-10-10, broadcast around the base of the tree out past the ends of the branches (the dripline). Be sure to fertilize before July 15 to avoid pushing new growth that may not harden off in time for winter. Please remember that more is not better when it comes to fertilizer. As the tree grows, you should increase the amount of fertilizer applied annually by one-half pound until you reach the maximum of five pounds of 10-10-10 per tree.

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