Peach Leaf Curl: Identifying and Addressing the Problem - Backyard Spruce (2024)

Why are my Peach Tree Leaves Bubbling? Peach leaf curl, also referred to as leaf curl, is a condition caused by the Taphrina deformans fungus. It impacts the blossoms, fruit, leaves, and shoots of peaches, ornamental flowering peaches, and nectarines.

It is a common issue for backyard gardeners in Zone 5-6 who cultivate these trees. The distorted, reddened foliage that it produces is noticeable in the spring, and severe cases can lead to a significant reduction in fruit yield.

Table of Contents

Identification and Harm

At the onset of spring, peach leaf curl manifests as reddish patches on developing leaves. These areas thicken and pucker, resulting in curled and distorted leaves. The thickened regions eventually turn yellowish and then grayish-white as the leaf curl fungus produces velvety spores on the leaf’s surface.

Affected leaves later turn yellow or brown, some remaining on the tree while others fall off. This leads to a second set of leaves developing more normally unless wet weather persists. The defoliation in spring can leave branches exposed to sunburn.

Peach Leaf Curl: Identifying and Addressing the Problem - Backyard Spruce (1)

The peach leaf curl pathogen also targets young green twigs and shoots. Affected shoots become thickened, stunted, distorted, and may die. While reddish, wrinkled areas may occasionally appear on fruit surfaces, these infected fruit areas can become corky and prone to cracking as the season progresses.

If left untreated over several years, the tree’s health may deteriorate, necessitating removal.

Infection Life Cycle

Symptoms on leaves typically appear about two weeks after they emerge from buds. The fungus grows between leaf cells, causing them to enlarge abnormally, resulting in swelling and distortion of the leaf. Red pigments accumulate in the distorted cells. Fungal cells penetrate the cuticle of distorted leaves, producing elongated sac-like structures called asci that release sexual spores known as ascospores, giving the leaf a grayish-white, powdery appearance. Ascospores are dispersed in the air, landing on new tissues and germinating to form bud-conidia.

Throughout the hot, dry summer, the fungus survives as ascospores and bud-conidia on the tree’s surfaces. When fall brings cool, wet conditions, ascospores germinate to produce more bud-conidia. The bud-conidia, both old and new, multiply by budding.

A film of bud-conidia forms on the tree’s surface over time. In spring, splashing water from irrigation or rain helps move the bud-conidia to infect new leaves.

The disease thrives during cool, wet periods when leaves are emerging. Optimal fungal growth occurs at 68°F with a minimum of 48°F and a maximum of 79° to 87°F. Bud-conidia budding happens at or above 95% relative humidity. Moisture from rain, dew, or irrigation for over 12.5 hours at temperatures below 61°F is necessary for infection. Prolonged wetness over two days leads to maximum infection. Infection may not manifest if temperatures stay above 69°F, and the disease’s development slows in cool weather.

Peach leaf curl stops progressing when new growth ceases or when the weather becomes dry and warm (79° to 87°F).

Peach Leaf Curl Management

To prevent peach leaf curl, consider utilizing resistant peach and nectarine varieties in gardening Zone 5-6. For nonresistant varieties, apply a fungicide annually after leaf drop, typically in late November in cooler regions and as late as early January in warmer areas.

Peach Leaf Curl: Identifying and Addressing the Problem - Backyard Spruce (2)

A single early treatment while the tree is dormant is usually effective, with a potential secondary spray in high rainfall regions or exceptionally wet winters.

Apply the second spray as flower buds start to swell but before green leaf tips emerge.

Resistant Peach Tree Varieties

Several peach varieties exhibit varying levels of resistance to leaf curl. Frost, Indian Free, Muir, and Q-1-8 are currently available resistant options.

The Frost cultivar is notably tolerant but may require fungicide applications in the initial 2 to 3 years.

Redhaven peach and its derivatives are also tolerant to peach leaf curl, while Redskin peach and related options range from susceptible to highly susceptible.

Fewer nectarine varieties show resistance to leaf curl, with Kreibich being a notable exception.

Fungicide Types

Copper

Historically, fixed copper products have been popular among home gardeners for disease control. The metallic copper content, measured as metallic copper equivalent (MCE) on the label, influences product effectiveness.

Various formulations containing basic copper sulfate, cupric hydroxide, or copper oxychloride sulfate are available. Currently, consumer options include liquid products with copper ammonium complex with 8% MCE, enhancing their efficacy. Although a highly effective product with 90% tribasic copper sulfate MCE is no longer widely available since 2010, remaining supplies can still be used.

Copper ammonium complex products can be improved by adding horticultural spray oil, aiding in aphid, scale insect, and mite control. Copper soap fungicides are also on the market and show promise in tree protection.

Note that overusing copper products across multiple seasons can lead to copper accumulation in the soil, potentially harming soil organisms and aquatic life if leached into waterways.

Bordeaux Mixture

Copper sulfate, while less effective alone, can form a potent fixed copper product when mixed with hydrated lime to create Bordeaux mixture.

This concoction proves impactful against peach leaf curl, though it must be prepared immediately before application, as it isn’t commercially available.

Other Fungicides

Chlorothalonil is a synthetic fungicide alternative to copper-based products for managing peach leaf curl in residential settings.

It should be noted, that lime sulfur products are no longer approved for backyard use.

Fungicide Application

When applying fungicides, ensure thorough coverage of the trees to achieve optimal disease control. Pesticide labels should always be consulted for correct usage, rates, toxicity, and disposal instructions. Appropriate protective gear, including goggles, must be worn when handling pesticides.

Physical Controls

While leaf curl symptoms mostly emerge in early spring, little can be done to mitigate the disease during this period. Some gardeners opt to remove diseased leaves or prune infected shoots, but their effectiveness in control remains uncertain. Diseased leaves typically fall off within a few weeks, being replaced by new healthy leaves unless persistent rain occurs.

Peach Leaf Curl: Identifying and Addressing the Problem - Backyard Spruce (3)

Severe peach leaf curl cases can hamper tree growth, prompting potential fruit thinning later in the season.

Fall pruning before applying fungicides can reduce overwintering spores and lower the required fungicide amount.

If your trees exhibited leaf curl symptoms in spring, ensure treatment during the subsequent fall and/or winter to prevent significant losses in the following year.

Peach Leaf Curl: Identifying and Addressing the Problem - Backyard Spruce (2024)

FAQs

How do you treat curly leaf curl on peach trees? ›

Leaf curl can usually be controlled satisfactorily by a spray of a suitable registered fungicide at any stage of dormancy. Most effective control is achieved by spraying when the buds are swelling but before they have opened. It's not possible to control the fungus once it's entered the leaf.

Can leaf curl be reversed? ›

Once the signs of peach leaf curl appear, there is no reversing it. There is no treatment you can give the tree that will stop or eliminate the disease once it has appeared in the Spring. Be sure to spray the tree with a copper-based fungicidal dormant spray next Winter.

Will leaf curl go away on its own? ›

Leaf curl disease shows up in spring, does the damage, and then disappears (until next spring). It will have disappeared by late summer. However, you may still be able to find signs of it, if you know what to look for. If your trees were infected last spring, they should have completely recovered by mid to late summer.

What is the best homemade spray for peach leaf curl? ›

Mix 1/4 cup of concentrate of the garlic concentrate with 1 Gallon of water in a sprayer like this one Chapin 61802 4-Gallon ProSeries Plus Backpack Sprayer with Bonus Foaming, Translucent White. You can add in a drop or two of natural soap, we use a natural, liquid castille soap.

Does apple cider vinegar help with leaf curl? ›

Leaf curl starts appearing in early spring on stone fruit trees. Spray a mixture of apple cider vinegar and water in winter and early spring when buds appear, then every couple of weeks. This will help with brown rot, black spot and leaf curl, to name a few.

Will neem oil stop peach leaf curl? ›

Spraying in winter and again in early spring is your best bet of keeping the fungus at bay. Organic approved sprays such as Neem Oil, Horticultural Oil, Bi-Carb and Copper all work but we've found Copper to be by far the most effective against leaf curl.

Can you eat peaches with peach leaf curl? ›

Most often the disease will not show up on the developing fruit, but occasionally it does affect fruit, causing corky areas to develop on the fruit surface. Those fruits are still okay to eat—just cut away the affected area.

What is the best spray for leaf curl? ›

Best Treatment for Leaf Curl

Where Leaf Curl has been severe in the previous year, trees can also be sprayed with Yates Liquid Copper Fungicide in autumn when the leaves drop, plus at the first sign of bud swell and again one week later.

What fungicide is good for peach curl? ›

Peach leaf curl is not difficult to control. A single fungicide (copper or chlorothalonil) application made in the fall after leaves have dropped or in spring before bud swell will control the disease. The spring application must be made before bud swell.

Is it too late to spray peach trees? ›

To prevent peach leaf curl, trees must be sprayed with a fungicide after their leaves have dropped and they are dormant. This is usually in late November, or December. If it is a particularly wet winter, a second application of fungicide can be made in early spring, just as buds begin to swell.

Should I cut off leaf curl? ›

Manually removing the infected leaves from the tree can help control the spread of Peach Leaf Curl. The discarded leaves contain fungus spores that can overwinter in the soil beneath the tree and reactivate in the spring.

What is the best treatment for curling leaves? ›

To control leaf curl, spray with PLANThealth Copper Fungicide soon after pruning, just before bud burst happens in Spring. Disease is often carried between plants by sap sucking insects. Use Organic Super Spraying Oil to control these insects before they can spread disease.

Can you save a peach tree with leaf curl? ›

Your Peach or Nectarine Will Survive

Peach Leaf Curl will cause the leaves to fall off and the fruit production of the tree can be affected. However, gardeners are usually relieved to hear that this disease rarely kills trees and can be easily managed if treated with a fungicide during the dormant season.

How often should I spray for peach leaf curl? ›

Generally a single early treatment when the tree is dormant is effective, although in areas of high rainfall or during a particularly wet winter, it might be advisable to apply a second spray late in the dormant season, preferably as flower buds begin to swell but before green leaf tips are first visible.

Can you treat peach leaf curl in summer? ›

Since the fungus overwinters on the bark and in the bud scales, it is vulnerable to the fungicide. If the trees are badly affected, you can spray again in the late winter or early spring, when the buds swell. Do not use these fungicides in warm weather or after the leaves and flowers come out of the buds.

What do you spray on curly leaf on fruit trees? ›

Best Treatment for Leaf Curl

Where Leaf Curl has been severe in the previous year, trees can also be sprayed with Yates Liquid Copper Fungicide in autumn when the leaves drop, plus at the first sign of bud swell and again one week later.

What is the remedy for curly leaf? ›

To control leaf curl, spray with PLANThealth Copper Fungicide soon after pruning, just before bud burst happens in Spring. Disease is often carried between plants by sap sucking insects. Use Organic Super Spraying Oil to control these insects before they can spread disease.

Can peach leaf curl spread to other plants? ›

Peach leaf curl will not affect your apple, orange, mandarin or lime trees, but will affect peach and nectarine trees. Peach leaf curl is caused by the fungus Taphrina deformans. The fungus survives the winter as spores (conidia) on bark and buds. Infection occurs very early in the growing season.

References

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