What Is Peach Leaf Curl?
Peach leaf curl, also known as curly leaf, curly blight or leaf blister, has been recognized as a common disease since the early 1800s. It is caused by the fungus Taphrina deformans and can affect the blossoms, fruit, leaves and shoots of peaches and nectarines. Peach leaf curl is the most common disease found in backyard orchards. Cool (48-68°F) wet weather when leaves are first opening favors the disease. Watch our video on Peach Leaf Curl where Tricia shows how to care for your trees.
Life Cycle of the Fungus
Symptoms appear after leaves emerge and begin to grow. The fungus causes cells in the infected portions of the leaves to grow abnormally large, causing the distorted look to the leaves. The fungus eventually produces reproductive bodies called asci that contain the spores. You will see a velvety-like appearance to the leaves, this is caused from the spores or ascospores. They are released into the air and infect other parts of the tree or other trees. In the newly infected areas the fungus continues to multiply and "cover" the tree and remain dormant in the bark and around the buds. The following spring the fungus is moved by rain or irrigation and infects new leaves. And the cycle continues. If not treated, the infection can weaken the tree and cause a decline in fruit production.
Treatment for Peach Leaf Curl
Products available to the home orchardist are those with lower Metallic Copper Equivalent (MCE) of about 8%, such as Liqui-Cop. Effectiveness can be improved with a sticker such as Horticultural Oils. Follow the instructions for all products and make sure you use appropriate safety equipment during application. Apply fungicide to point of runoff and a good rule of thumb is to apply three times during the dormant season: after leaf drop (around Thanksgiving), winter (around Jan.1) and before bud swell (around Feb, depending on where you live). You can apply less often if the infection the previous year was light.
Effective for controlling peach leaf curl but not registered for sale for the backyard orchard and not available for sale in many states.
Cultural ControlsOnce the tree is infected there is not much to be done to get rid of the disease that season. But it is very important to maintain the vigor of the tree throughout the active growing season.
- Thin the fruit to reduce the demand on the trees' resources. For peaches and nectarine, thin fruit to at least 3 inches apart. Remove diseased or cracked fruit and place in the trash, not your compost pile.
- Fertilize with nitrogen by mid-June, a good balanced fruit tree fertilizer is a good choice.
- Keep watered to reduce water stress.
- Clean up dropped leaves or fruit around the base of the tree to reduce spreading to other trees. Don't put these in the compost pile, the spores can remain dormant for some time.
Another option, especially if you have to remove a weakened tree, is to consider putting in resistant or partially resistant varieties such as Frost, Indian Free, Muir, or a multigraft peach tree that contains all those varieties. If you don't care for these varieties, choose a tree that blooms later in the season. You may see less disease developing in these due to the later bloom time.
Don't let peach leaf curl ruin your favorite peach or nectarine. Yearly spraying with a fungicide listed for peach leaf curl will keep the disease in check and allow for a healthy tree and a bountiful harvest.
Jaqui, peach leaf curl does not usually effect the fruit, just the leaves.
I have been snipping off the leaves with curl and noticed that there are allot of fruit coming. Will leaf curl effect the fruit.
I think it is important for every gardener and farmer to understand that any pesticide/herbicide/fungicide, even organically approved, will simply breed more resistant pests/weeds/fungus (a point of view supported by Mark Shepherd, Dr. Lee Reich, and many others). The individual pests that survive the spray will be inherently resistant to it and produce offspring resistant to it. On the other hand, composting or animal feeding your diseased or pest infected material is the best way to develop natural controls for them. In doing so we are providing food and habitat for those other organisms that eat or compete with the problematic species. Ultimately, if your tree can’t survive where you are without a lot of help, it’s not the tree you want unless you want to be buying a bunch of biocides and doing endless work. As Mark Shepherd says, “Why do we as farmers and gardeners fight so hard to grow things that want to die while killing the things that want to live?” Instead I’d spend my money and time finding varieties that do well where you are. Permaculture practices like I am advocating here do require an inversion of our common interventionist thinking, but if we want to get off the hamster wheel of buying biocides and throwing away our organic matter, it’s the best option I know of.
Every spring or at first sign of peach curl, put a bag of chicken manure around your peach tree and water deeply.
Been doing this for many years and never had a problem.
Another treatment is with trichoderma harzianum, usually sold for root disease. I have sprayed it after the leaf curl starts and it stops the curl. If we get more rain then the curl may start up again and can be stopped by spraying more trichoderma. A fresh batch is more effective so look for a date on the package.