Harvesting fresh peach fruit straight from the branch has been the dream since you planted your tree. You’re providing the right soil, water levels, and more to keep it happy, but you’ve suddenly spotted an unsightly curl in some of the new leaves – so what does this mean?
Peach tree leaves begin curling due to an infection caused by the pathogen Taphrina deformans. This fungus lies dormant in yeast-like form to affect developing leaves during wet spring conditions and causes the leaves to produce more cells than necessary, resulting in deformed, distorted foliage.
There are certain preventative steps you can take from applying appropriate fungicide solutions to planting peach tree varieties that are resistant to the devastating fungus. An awareness of the fungus’ life cycle can also help you understand and prepare for changes in the environment. Let’s look at each aspect of peach leaf curl in greater detail.
Peach Leaf Curl
Also known as ‘leaf blister’, this disease has been noted since the early 1800s and also affects the flowers, fruit, and shoots of peach trees.
What Causes Peach Leaf Curl?
When spring conditions are consistently cool and wet, temperatures can dip below 61°F, and if emerging peach leaves are exposed to over 12 hours humidity, this provides an ideal environment for fungal spores to enter certain leaf cells and spread, distorting and discoloring the surface.
Peach Leaf Curl Symptoms – How To Identify
- Puckered and ballooning sections
- Tight curling and warping
- Raised reddish warts
- Velvety surface
- Thickened sections later turn yellow, gray, and powdery
Fruit (rare signs)
- Reddish, wrinkled patches that later become corky and cracked
- Premature fruit drop
- Young twig tissue appears swollen
- Established shoots thicken and distort before becoming stunted and dying off
When Peach Leaf Curl Is Most Likely To Occur
Leaf curl typically appears within two weeks of the leaves emerging from their buds, and according to the Agricultural Division at the University of California, “maximum infection occurs when trees are wet for 2 days or more” and when temperatures are “between 47°F and 60°F”.
Leaf curl is least likely to happen when spring temperatures are reliably moderate (around 69°F and above). According to the Farmer’s Almanac, peach trees fare well in USDA growing zones 4-9, but “grow best in zones 6-8”.
Can a Peach Tree Recover From Leaf Curl?
Fortunately, there is no secondary spread of the fungus to new leaves that develop later in the growing season, so as soon as infected leaves, shoots, and fruit drop off the tree, no new symptoms should appear.
Rain and wind can carry spores onto other parts of the tree where they lie dormant until the cool, wet fall weather allows them to germinate, but they cannot infect budding leaves the following spring if conditions are warm and dry (79-87°F) during their development.
When Is It Too Late To Spray for Peach Leaf Curl?
Once the leaves have opened out it will be too late for a spray remedy. Plant protection expert Karey Windbiel-Rojas at the University of California strongly recommends applying fungicide “once the leaves have fallen in late November or December, or between January and February during wet winters.”
Are Any Peach Trees Resistant to Leaf Curl?
Peach tree varieties that are fully or partially resistant to leaf curl include Indian Free, Frost, Muir, Q18, and the cultivar ‘Redhaven’. Frost peach trees require fungicide applications for the first 3 years of growth and ‘Redskin’ peach trees are highly susceptible to leaf curl.
Peach Tree Leaf Curl Treatment
During the advised period, spray the tree with copper-based fungicide until there is run-off. Those containing the active ingredient MCE and Horticultural Oil are most effective in helping kill off vulnerable, dormant spores.
Thin the Fruit
Growth is stunted when the symptoms are severe so conserve the tree’s energy for the winter ahead by pruning some of the peach fruit in fall to reduce spore numbers.
Reduce Water Stress
Ensuring the tree receives at least one inch of water per week will help it cope better during leaf and fruit loss.
Apply a high-nitrogen organic fertilizer once around mid-June to help the tree maintain its energy long into the growing season.
Homemade Spray for Peach Leaf Curl
Californian fruit plant hobbyist Joe on the Growing Fruit forum shares his recipe for an organic spray:
- Add 2oz of 5% Vinegar to 1-gallon water.
- In a small cup, mix 2tbsp Melaleuca/Tea Tree oil, 1tbsp Neem Oil, and 2tbsp Dawn liquid dish soap.
- Add the vinegar/water solution to the cup and stir well.
- Pour the mix into a clean spray bottle and shake well. Apply in the late afternoon.
Another gardener over at Grow Organic also suggested soaking past-use minced onion, straining the juice, and adding a few drops of detergent for a natural sulfur-based fungicide spray!
Peach Leaf Curl Prevention
- Plant disease-resistant trees where possible
- Treat with fungicide as soon as the leaves fall
- Use two fungicide applications in wet climates – once after the leaves have fallen and again right before the buds begin to swell
- Apply chicken manure to the tree roots. The fungus Mycelium within manure is known to provide disease resistance.
- Remove fallen infected leaves and peach fruit at the base of the tree to prevent further spore spread from rainwater splashes
Can Leaf Curl Spread to Other Trees?
Peach, nectarine, and occasionally apricot trees are primarily affected by the Taphrina deformans fungus. Other fruit tree varieties such as orange, apple, and lime can be attacked by the fungus in the event of spores carried by rain and wind, but they will be far less susceptible to infection.
Why Are My Peach Tree Leaves Turning Yellow?
Yellow leaves combined with leaf drop usually point to a lack of water. Be sure to provide supplemental watering during low rainfall. Mature peach trees need between 1-1.5 inches of water per week but can benefit from 3 waterings per week during periods of drought.
To summarize, peach leaf curl is most likely to happen during cool, wet spring conditions and can’t be stopped once leaves emerge.
The spread of the disease, however, can be reduced with proactive steps such as timely fungicide applications and TLC in terms of water and pruning to help your peach tree maintain its strength.