Peach leaf curl (Taphrina deformans) is a common fungal disease of peaches, ornamental peaches, and nectarines. It has also been found in apricot trees and occasionally in almond trees. The fungus infects leaves, fruits, blossoms, and shoots. While peach leaf curl is serious, there are ways to protect your trees from it.
Peach leaf curl is a problematic fungal disease that affects peach and nectarine trees. It causes leaves to pucker, distort, and turn reddish in color. If left untreated, it can lead to defoliation, reduced fruit production, and overall tree decline. The key to managing peach leaf curl is taking preventative action at the right time with effective fungicide sprays. This comprehensive guide covers everything you need to know about properly spraying peach trees to control leaf curl.
Understanding Peach Leaf Curl
Peach leaf curl is caused by the fungus Taphrina deformans. It infects new leaves, shoots, blossoms, and fruit, primarily in the spring. Wet, cool conditions favor the disease. Once symptoms appear on leaves as they emerge, it is too late to treat that year’s infection.
Key signs of peach leaf curl
- Reddened, thickened, puckered leaves
- Distortion and curling of leaves
- Powdery gray coating on leaves
- Premature leaf drop
- Reduced fruit production
- Twig dieback
If left uncontrolled over successive years, peach leaf curl can seriously damage trees. The key is being proactive with preventative fungicide sprays to stop the fungus from infecting emerging growth.
When to Spray Peach Trees for Leaf Curl
Timing is critical when spraying peach trees to prevent leaf curl. The optimum window is during the dormant season after leaves drop in late fall/early winter through late winter before buds start swelling.
Fall application:
- After leaf drop, usually November-December
Late winter application:
- Before flower buds begin to swell, usually January-February
- Can apply a second spray if the fall application was missed
Spraying during this dormant period allows the fungicide to coat buds and kill overwintering fungal spores before they can infect tender new growth. Once leaves emerge in spring it is too late to treat.
How to Spray Peach Trees Effectively
Proper application technique and fungicide selection are vital for success. Follow these tips:
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Use a copper-based fungicide specifically labeled for peach leaf curl on the label. Look for active ingredients like copper sulfate, copper hydroxide, or copper octanoate.
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Mix according to label directions Do not over or under apply
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Spray thoroughly until dripping to cover every bud and branch. This coats all potential infection sites.
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Time applications carefully based on weather forecasts. Avoid rain within 24 hours which can wash away treatment.
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Add a spreader-sticker to the mix to help the spray adhere and penetrate.
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Wear protective gear like goggles, gloves, long sleeves, pants, and boots when spraying.
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Consider plant-based oils like neem oil and horticultural oils as organic options. They help smother fungal spores.
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Prune trees before spraying to improve spray coverage and tree health.
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Remove and destroy any leaves/branches with symptoms to reduce inoculum.
Repeating this fungicide spray yearly is key to protecting trees from leaf curl infection. Be diligent with thorough coverage during the optimal treatment window.
Alternative Organic Sprays
For those wishing to avoid synthetic fungicides, there are some organic or non-chemical options to try. However, these generally provide less reliable disease control than copper fungicides.
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Neem oil: Derived from the neem tree, it contains antifungal properties and can deter fungal spore germination when sprayed on trees during the dormant season.
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Horticultural oils: These oils help smother overwintering fungal spores. Apply during the dormant period before bud swell.
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Baking soda: Mix 1 tablespoon of baking soda per gallon of water with a small amount of mild soap. The soap helps the spray stick to the tree. Some find this spray deterred fungal growth when applied during the dormant season.
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Milk spray: Some gardeners report success spraying trees with a 1:1 mixture of milk and water during the dormant season to prevent leaf curl. The proteins in milk may inhibit fungal growth.
While these options are lower risk than traditional fungicides, they generally provide less effective disease control. Their results can be variable.
Important Considerations
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If peach leaf curl symptoms do appear, it is too late to spray that year. Focus efforts on preventative sprays the following dormant season.
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After infection,trees will usually produce a second flush of healthy foliage once the weather warms up.
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While spraying dormant trees is ideal, oil applications can smother overwintering spores if applied before buds swell in early spring.
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Monitor your trees closely and adjust your spray program based on effectiveness. If leaf curl persists, you may need an earlier and/or additional dormant spray.
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Preventative spraying is most critical on young or already infected trees. Healthy, established trees can occasionally skip a year of treatment.
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Choose resistant peach varieties like Frost, Q-1-8, and Muir when possible to avoid frequent fungicide sprays.
Controlling peach leaf curl centers on properly timed preventative fungicide sprays to protect trees during the critical dormant period. Focus on thorough coverage using recommended products like copper-based fungicides. Organic options can also be trialed, but may offer less reliable control than traditional fungicides. With a consistent spray program, you can keep pesky leaf curl at bay and enjoy bountiful, healthy harvests from your peach trees.
Peach Leaf Curl Symptoms
About two weeks after the leaves emerge, they develop yellow or reddish raised areas. They become distorted and puckered as they grow. The raised areas become red or purple. Leaves often fall off of the tree. The leaves that remain will develop a white powder on them. This powder is velvety spores of the fungus, ready to spread when water splashes on them.
Infected shoots are distorted and have small yellowish leaves, or leaves in rosettes (whorled). Flowers are distorted and may drop without forming fruit. The fruit has raised, scaley areas on it.
Because the infected leaves are not able to photosynthesize on the distorted, raised areas, they are costly to the tree. Often if the leaves fall off the tree, it will put out new leaves that are not usually diseased. However, in doing this, they use precious energy needed to grow fruit. If left untreated, peach and nectarine trees will die in two or three years.
The Lifecycle of Peach Leaf Curl
Peach leaf curl is caused by a fungus that infects the bud scales. It forces the leaf, twig, flower, or fruit to produce many more cells in an area than they should. This causes the raised places on the infected part. Cells of the fungus break through the cuticle of the leaf and form structures called asci. Inside these structures, the fungus reproduces sexually to form ascospores. These become the white powder on the leaves and other affected parts of the tree. When water is splashed on the spores, they spread to uninfected tissue and divide into bud-conidia.
The ascospores and bud-conidia survive the summer on the tree. When it gets cool and wet outside in the fall, the ascospores divide into bud-conidia. These bud-conidia continue to divide and eventually form a thin film on the surface of the tree. They overwinter there until spring comes. When water splashes on them, they use the water to travel to new, uninfected tissue.
How to Treat Leaf Curl in Peach and Nectarine Trees
FAQ
What is the best spray for leaf curl on peach trees?
The synthetic fungicide chlorothalonil currently is the only other noncopper fungicide available for managing peach leaf curl on backyard trees. Lime sulfur (calcium polysulfide) products no longer are registered for backyard use.
How do you treat leaf curl in peach trees?
Leaf curl is controlled by applying “sulfur” or copper-based fungicides, that are labelled for use on peaches and nectarines. Spray the entire tree after 90% of the leaves have dropped in the fall and again in the early spring, just before the buds open.
How do you make homemade leaf curl spray?
- Mix lime and water. Dissolve 100 grams of builders’ (hydrated) lime in half a standard (plastic) bucket of water. …
- Mix copper sulfate and water. Dissolve 100 grams copper sulphate in a separate half bucket of water. …
- Spray. Pour the mix into a sprayer. …
- Wash.
Will peach leaf curl go away by itself?
Leaf curl disease shows up in spring, does the damage, and then disappears (until next spring). If your trees were infected last spring, they should have completely recovered by mid to late summer. They usually grow lots of healthy new leaves (like the photo below).