By: Nikki Tilley, Author of The Bulb-o-licious Garden
Peach tree leaf curl is one of the most common disease problems affecting nearly all peach and nectarine cultivars. This fungal disease affects all aspects of these fruit trees, from blossoms and fruit to leaves and shoots. Learning about peach leaf curl symptoms is a crucial step in the treatment or control of this disease.
Signs of peach leaf curl usually appear within two weeks following leaf emergence. Symptoms of peach tree leaf curl include leaf curling and discoloration. Leaf color may be yellow, orange, red, or purple. There may also be deformed reddish colored warts on the leaves. Later leaves may turn gray or powdery looking.
Fruit may also become infected, developing raised wart-like growths. Infected fruits often drop prematurely.
Peach leaf curl can affect new twigs and shoots as well. New twig tissue becomes swollen while affected shoots become thick, stunted, and die.
While treatment of peach leaf curl is not always effective once symptoms occur, the disease is fairly easy to prevent. Applying a fungicide spray in autumn following leaf fall or just before budding in spring can usually stop peach leaf curl.
While a single treatment in fall is usually sufficient, areas prone to wet weather may require an additional treatment in spring. Infections are greater following rain, as spores are washed into buds.
Controlling peach leaf curl with fungicides is the only way to prevent this disease. So what are the most effective fungicides for peach leaf curl? The safest and most effective fungicides available to home gardeners are fixed copper products. These may be listed as metallic copper equivalent (MCE) on product labels. The higher the MCE, the more effective the fungicide will be. Other less effective fungicides include lime sulfur and copper sulfate.
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Read more about Peach Trees
Mark Longstroth and Bill Shane, Michigan State University Extension - March 13, 2012
Before or during bud swell is the time to treat peach leaf curl, a fungal disease that deforms leaves and then defoliates peach trees.
The warm weather forecast for this week and next, with highs forecast in the 70s and lows near 50, means that fruit trees will begin growth and grow rapidly. We may be several weeks ahead of normal by the next spring freeze which looks to be a week or more away. Growers need to get out their early disease control sprays.
For peach growers, the first spray of the year is to control “curl leaf” or peach leaf curl. Peach leaf curl is an important disease in Michigan. This disease can defoliate peach and nectarine trees. The fungus that causes peach leaf curl overwinters on the tree. Infections take place in the spring as the buds open. The fungus infects peach buds from bud swell to bud opening under wet conditions. Air temperatures between 50 to 70°F are ideal. Rain or dew moves spores into the opening buds, allowing the infection of young tissue. The disease requires about 10 to 11 hours of wetness for infection to occur. Prolonged cool wet periods during bud burst can result in severe infections. Early spring applications at or before bud break are effective in controlling this disease.
Effective controls include Bravo, Ziram, Carbamate and copper compounds. Most growers try to use copper early. If you believe an infection may have already occurred, you are better off using Bravo or Ziram rather than copper because these materials are more effective after infection. Later applications can reduce the severity of the disease. Copper compounds have the added benefit of providing some suppression of bacterial spot as well. (See Bill Shane’s article on copper compounds used on fruit). If you are going to use copper, be sure to use the rate of 4 to 8 pounds of metallic copper per acre. Some product labels may recommend less and some Michigan growers have been disappointed with lower rates. Peach growers in Berrien County, Mich., are already putting on their copper sprays now.
Once leaves are infected there is no effective fungicide treatment. The leaves are infected in the bud once they have emerged they are no longer susceptible to infection. Infected leaves become crinkled, turning orange or red. The leaves become thick and powdery with spores as the fungus sporulates. Infected leaves eventually fall off. The tree will grow new leaves.
Peach leaf curl weakens the tree by removing leaves during early growth. This reduces energy the tree can absorb from the sun, weakening the tree, and reduces growth and fruit size. Heavy fruit thinning reduces stress on the tree and increases the likelihood of a marketable crop. Severely infected trees should receive an increased ration of nitrogen fertilizer. This will help the tree replace lost leaves and maintain vigor.
This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).
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Peach trees are, unfortunately, often susceptible to fungus diseases and other pathogens which can significantly reduce the crop and tree’s health. Sometimes the only solution is spraying the tree with a fungicide or dormant oil. These sprays contain naturally occurring chemicals which control the spread of pathogens, and they are applied before the tree begins bud and shoot development in the spring.
Peach tree borer, scales, and other common pests of peach trees can be controlled by applying a dormant oil on the tree in winter.
Spray the tree before it shows new, green growth in spring but when temperatures are above 40ºF (4.4ºC).
Always read the dormant oil package instructions carefully before mixing or using the product, and be sure you have the necessary spraying equipment and protective clothing for doing this job.
Peach leaf curl is a common fungus disease affecting peach and nectarine trees. Red and puckering leaves in summer is an easy to spot symptom, but by this time, it is too late to take action until the following winter. Then, treatment with a copper-based fungicide spray can often get the problem under control for the next growing year.
Spray copper and sulfur fungicides when the leaves have fallen in the fall. An additional spraying can be done in the spring just as the buds start to swell but before green tips appear on the twigs and branches.
Cover the tree and all branches completely with the spray. During wet weather it may be necessary to spray more than once in a season. Always apply these sprays well before or after bloom time because they can interfere with the activity of bees and other pollinators needed for good fruit set.
Peach leaf curl is a fungal disease that distorts the leaves of peaches and nectarines, and sometimes also apricots. The leaves crumple and thicken, and often have red blistery patches. Ultimately they fall off, and if your peach tree only has a handful of leaves left, it’s obvious that it won’t perform well.
Symptoms of peach leaf curl include shrivelled, deformed leaves and red blotches. Photo: Shutterstock
Luckily, there is a way to prevent it infecting your peach trees and that is to keep the rain off them. The fungal spores need wet conditions to germinate so covering the trees with a clear plastic sheet between November (after leaves have fallen) and mid-May to keep their branches dry will prevent infection. That’s why, more often than not, peaches and nectarines are grown against walls, to make covering them easy.
The sheeting shouldn’t form an air-tight seal around the tree, simply cover it from the top and down the front, like a mini lean-to greenhouse. Leave gaps at the sides so insects can still get in to pollinate the flowers, or you won’t get any fruit anyway and your efforts will have been in vain.
If your peach does show signs of infection, remove any leaves as soon as you spot the symptoms. If the tree is otherwise healthy, it should hopefully produce a second flush of leaves that won’t be reinfected.
If you are considering planting peaches or nectarines, there are some cultivars that have more resistance to peach leaf curl than others. Peach ‘Avalon Pride’ is said to be the best.
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Peach leaf curl, also known as leaf curl, is a disease caused by the fungus Taphrina deformans. Peach leaf curl affects the blossoms, fruit, leaves, and shoots of peaches, ornamental flowering peaches, and nectarines, and is one of the most common disease problems for backyard gardeners growing these trees. The distorted, reddened foliage that it causes is easily seen in spring. When severe, the disease can reduce fruit production substantially.
Peach leaf curl first appears in spring as reddish areas on developing leaves. These areas become thickened and puckered, causing leaves to curl and severely distort. The thickened areas turn yellowish and then grayish white, as velvety spores are produced on the surface by the leaf curl fungus. Later affected leaves turn yellow or brown and can remain on the tree or may fall off they are replaced by a second set of leaves that develop more normally unless wet weather continues. The loss of leaves and the production of a second set result in decreased tree growth and fruit production. Defoliation in spring may expose branches to sunburn injury.
The peach leaf curl pathogen also infects young green twigs and shoots. Affected shoots become thickened, stunted, distorted, and often die. Only rarely do reddish, wrinkled to distorted (or hypertrophied) areas develop on fruit surfaces. Later in the season these infected areas of fruit become corky and tend to crack. If leaf curl infection builds up and is left uncontrolled for several years, the tree may decline and need to be removed.
Leaf symptoms appear about 2 weeks after leaves emerge from buds. The fungus grows between leaf cells and stimulates them to divide and grow larger than normal, causing swelling and distortion of the leaf. Red plant pigments accumulate in the distorted cells. Cells of the fungus break through the cuticle of distorted leaves and produce elongated, sac-like structures called asci that produce sexual spores called ascospores, which give the leaf a grayish white, powdery or velvetlike appearance. The ascospores are released into the air, carried to new tissues, and bud (divide) to form bud-conidia.
The fungus survives the hot, dry summer as ascospores and bud-conidia (asexual spores) on the tree’s surfaces. When the weather turns cool and wet in fall, the ascospores germinate to produce more bud-conidia. The new and old bud-conidia continue to increase in number by budding. Eventually a film of bud-conidia is formed on the tree’s surface. In spring, the bud-conidia move by splashing water from irrigation or rain and can infect new leaves.
Periods of cool, wet weather, when leaves are first opening on the tree, favor the disease. The optimum temperature for fungal growth in laboratory cultures is 68°F, the minimum is 48°F, and the maximum is 79° to 87° F. Budding of bud-conidia occurs at or above 95% relative humidity. Wetness from rain, dew, or irrigation for more than 12.5 hours at temperatures below 61°F is needed for infection. Maximum infection occurs when trees are wet for 2 or more days. Although leaves can be infected, symptoms might not appear if temperatures remain above 69°F. Cool weather prolongs the period of disease development by favoring the pathogen and slowing leaf growth. Development of peach leaf curl ceases when young tissue is no longer developing or when weather turns dry and warmer (79° to 87°F).
To prevent peach leaf curl, use resistant peach and nectarine varieties where possible. (See the Resistant Varieties section below.) For nonresistant varieties, treat trees with a fungicide every year after leaves have fallen. In cooler northern locations leaf fall usually is in late November. In warmer southern locations leaf fall can be as late as early January. 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.
A few peach varieties are available that are resistant or partially resistant to leaf curl. Currently available resistant varieties include Frost, Indian Free, Muir, and Q-1-8.
The peach cultivar Frost is reportedly very tolerant but must receive fungicide applications the first 2 to 3 years. Redhaven peach and most cultivars derived from it are tolerant to peach leaf curl, whereas Redskin peach and cultivars derived from it range from susceptible to highly susceptible to the disease.
There are fewer resistant nectarines, although Kreibich is one such variety.
Historically, the most commonly used fungicides available to home gardeners have been the fixed copper products. For all copper-containing products, the active ingredient, copper, is listed as “metallic copper equivalent,” or MCE, on the label. Various product formulations differ widely in their metallic copper content. The higher the MCE, the greater the amount of copper and the more effective the product will be. However, other factors such as coverage, use of additives as such stickers and spreaders, and frequency and duration of rain, which can wash off the copper, also will impact product effectiveness. In all cases, the copper is active only when it is wet, when the copper ions are in solution.
Fixed copper products include tribasic or basic copper sulfate, cupric hydroxide, and copper oxychloride sulfate (C-O-C-S), but currently only liquid products containing copper ammonium complex products with 8% MCE (e.g., Kop R Spray Concentrate [Lilly Miller brands] and Liqui-Cop [Monterey Lawn and Garden]) are available to consumers. The most effective copper product, 90% tribasic copper sulfate with a 50% MCE (Microcop), is no longer available to retail outlets, because the manufacturer withdrew the product in 2010, although remaining supplies still can be sold.
The copper ammonium complex products can be made more effective by adding 1% horticultural spray oil to the application mix the oil also aids in controlling some aphids, scale insects, and mites. Copper soap (copper octanoate) fungicides are also available, and preliminary research indicates they may provide some protection of trees.
Be aware that repeated annual use of copper products over many seasons can result in a buildup of copper in the soil, which eventually can become toxic to soil organisms, and if it moves into waterways, can harm some aquatic species.
Copper sulfate is not a fixed copper and, when used alone, is less effective than tribasic copper sulfate or other fixed copper products. However, if copper sulfate is mixed with hydrated lime to make a Bordeaux mixture, the copper sulfate and calcium in the lime react together to form a fixed copper product that is effective against peach leaf curl. Bordeaux mixture is not available for sale it must be mixed up just before application, and the ingredients can be very difficult to find. For information on preparing Bordeaux mixture see Pest Notes: Bordeaux Mixture.
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.
Thorough coverage with any fungicide is essential to obtain adequate disease control. Trees should be sprayed to the point of runoff or until they are dripping.
When using pesticides, always read and follow the label for usage, rates, toxicity, and proper disposal. Proper protective clothing and gear including goggles should be used when handling any pesticides.
Although symptoms of leaf curl are seen primarily in spring as new leaves develop, there is little you can do to control the disease at this time. Some people remove diseased leaves or prune infected shoots, but this has not been shown to improve control. Normally, diseased leaves fall off within a few weeks and are replaced by new, healthy leaves, unless it is rainy.
If a tree is severely affected with peach leaf curl this can stunt its growth, so consider thinning fruit later in the season. Pruning in fall prior to applying any fungicides can reduce spore numbers overwintering on the tree and reduce the amount of fungicide needed. If leaf curl symptoms occurred on your trees in spring, be sure to treat the following fall and/or winter to prevent more serious losses the following year.
Broome, J. C. and D. R. Donaldson. June 2010. Pest Notes: Bordeaux Mixture. Oakland: Univ. Calif. Agric. Nat. Res. Publ. 7481.
Flint, M. L. 1998. Pests of the Garden and Small Farm: A Grower’s Guide to Using Less Pesticide, 2nd ed. Oakland: Univ. Calif. Agric. Nat. Res. Publ. 3332.
Ingham, R., J. McMorran, C. M. Ocamb, J. W. Pscheidt, and M. Putnam. 2010. Peach Leaf Curl. In Pacific Northwest Plant Disease Management Handbook: An Online Guide to Plant Disease Control. Corvallis: Ore. State Univ. Accessed Jan. 21, 2011.
McCain, A. H. 1978. Peach leaf curl control for home gardeners in the San Francisco Bay Area. Calif. Plant Pathol. 43:4–5.
McCain, A. H., E. J. Perry, and G. W. Hickman. 1979. Leaf curl fungicides. Calif. Plant Pathol. 46:1–2.
Moller, W. J., A. H. McCain, and D. H. Chaney. 1979. Leaf Curl Control in Peaches and Nectarines. Oakland: Univ. Calif. Agric. Nat. Res. Leaflet 2613.
Ogawa, J. M., E. I. Zehr, G. W. Bird, D. F. Ritchie, K. Uriu, and J. K. Uyemoto. 1995. Compendium of Stone Fruit Diseases. APS Press, St Paul, Minn.
Rossi, V., M. Bolognesi, L. Languasco, and S. Giosue. 2006. Influence of environmental conditions on infection of peach shoots by Taphrina deformans. Phytopathology 96:155–163.
Pest Notes: Peach Leaf Curl
UC ANR Publication 7426
Authors: J. C. Broome, Plant Pathology, UC Davis/UC Cooperative Extension, Sacramento/Yolo/Solano Co. and C. A. Ingels, UC Cooperative Extension, Sacramento Co.
Produced by UC Statewide IPM Program, University of California, Davis, CA 95616
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One of the most common diseases of peach and nectarine cultivars is peach leaf curl. This is a fungal disease that will affect the aspect of these fruit trees, starting from blossoms and fruit going further to leaves. Thus, it is very important to treat it right away, to get the most nutritious peaches. So, keep on reading and check out the information on symptoms and treatment with a DIY fungicide spray.
How and when do peach leaf curl symptoms show up?
If you are looking for signs of peach leaf curl, you need to know they usually appear within two weeks. Thus, you need to be following leaf emergence to notice it right away. Some of the symptoms of peach leaf curl include discoloration and leaf curling, so you need to be careful watching. When it comes to color, the leaves may display a range of yellow or orange, and even red or purple. Furthermore, the leaves may also display some deformed reddish-colored warts. Even more, some of the leaves may turn gray or powdery looking if left untreated.
Now, these symptoms are very important to watch because fruits may become infected, developing raised wart-like growths. And you don’t want that, especially because infected fruits drop prematurely. Thus, if you want to save your peaches, keep reading for the treatment of peach leaf curl.
DIY Treatment with A Fungicide Spray
As we all know, preventing is always the first step. Thus, applying a fungicide spray in autumn following leaf fall is the perfect time to treat the peach leaf curl. While this treatment in fall is usually sufficient, you may need to apply an additional treatment in spring if you consider it necessary. Infections are greater following rain, so this is the reason for another application.
However, you need to learn how to make your own fungicide. This will give you control of the ingredients, many of which you already have in your home. Thus, this will basically be a Bordeaux mixture to control the fungal and bacterial diseases.
Your own Bordeaux mix consists of ground limestone and powdered copper sulfate. Thus, mix four parts of each with 50 gallons of water. If you need less, like for a gallon, reduce the recipe for this homemade plant fungicide to 6 1/2 to 8 teaspoons of the copper sulfate and 3 tablespoons limestone to 1 pint of water.
That’s it. You just learned how to make your own fungicide. However, you also need to be aware of using it responsibly. Thus, make sure to test it out on small surfaces of the plant so you won’t harm it excessively. In addition, it is important to not apply this mixture on a hot or brightly sunny day, because it will quickly lead to burning of the plant and its ultimate demise.