Leaf curl

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Leaf curl
Taphrina deformans 1.jpg
Peach leaf curl
Causal agents Taphrina fungus
Hosts peach, almond
Distribution America, Europe, Asia, Africa, Australia, New Zealand

Peach leaf curl is a plant disease characterized by distortion and coloration of leaves and is caused by the fungus Taphrina deformans , [1] which infects peach, nectarine, and almond trees. T. deformans is found in the United States, Europe, Asia, Africa, Australia, and New Zealand. [2] Peach leaf curl reduces the amount of leaves and fruit produced by peach and nectarine trees. [3]

Contents

Affected species

Peach leaf curl mainly affects peach, nectarine, and almond trees. Apricots are generally immune to peach leaf curl (instead, the major apricot diseases are blossom wilt and branch dieback caused by Monilinia fructicola in the spring and Eutypa lata in the summer). [4] [5] However, in an isolated case in Hungary in 2011, peach leaf curl was also identified in apricot trees. [6]

Symptoms

Peach leaf curl is a distinctive and easily noticeable fungal disease, and the severity of the symptoms depends on how early infection has occurred. Diseased leaves can usually be identified soon after they emerge from the bud, due to their red color and twisted shape. As the leaves develop, they become increasingly distorted, and ultimately thick and rubbery compared to normal leaves. The color of the leaves changes from the normal green to red and purple, until a whitish bloom covers each leaf. Finally, the dead leaf may dry and turn black before it is cast off. Changes in the bark are less noticeable, if at all. Fruit may fail to develop from diseased blossoms. Any fruit that does develop from a diseased tree is usually normal, but sometimes may also be affected, showing a reddish color. [3] Infected leaves fall early. The tree usually produces a second flush of leaves that is rarely diseased, except in an unseasonably cool and wet spring, because the fungus is not infectious at the normally higher temperatures in late spring and early summer.

Cause of peach leaf curl

The fungus T. deformans causes deformed young leaves, red blisters, and ultimately the whitish bloom that covers the leaf as the infection progresses. This white color is made of asci that break through the cuticle of the leaf. One ascus consists of eight ascospores that create conidia, which are ejected in early summer and spread by rain and wind. The fungus survives the winter on the surface of the host plant, such as on bark or buds. [2] In late winter or early spring, rainwater washes spores into the buds as they burst. Once this happens, no treatment is effective. In the spring, about two weeks after blossom, new leaves emerging from the infected buds are infected by the conidia. The disease may not occur every year due to variation in temperature and rainfall. Specifically, for successful infection, the fungus requires wet winters, where rain (not fog or dew) wets the tree for more than 12.5 hours at temperatures below 16 °C (61 °F). [7] The fungus cannot grow at temperatures below 9 °C (48 °F). [8]

Control of the disease

Various methods are applied.

If a tree has peach leaf curl in a particular year, the disease will inexorably take its course, but measures can be taken to sustain the tree or maximize crop yield: protecting the tree from further rain at temperatures below 16 °C (61 °F), providing nitrogen and excess water to minimize stress on the tree; applying greasebands around the trunk to protect from insect infestation; and thinning the fruit. It is unclear whether removal of infected leaves from the tree is beneficial. [8] Removing the infected leaves and fruit after they fall to the ground is sometimes also suggested but superfluous if, in the following winter, fungicides or rain protection are applied.

History

Peach leaf curl was first introduced in America in 1852 and has now spread all over the country. By 1947, the disease was costing the United States $2.5 to 3.0 million annually. [3]

Related Research Articles

<i>Uncinula necator</i> Species of fungus

Uncinula necator is a fungus that causes powdery mildew of grape. It is a common pathogen of Vitis species, including the wine grape, Vitis vinifera. The fungus is believed to have originated in North America. European varieties of Vitis vinifera are more or less susceptible to this fungus. Uncinula necator infects all green tissue on the grapevine, including leaves and young berries. It can cause crop loss and poor wine quality if untreated. The sexual stage of this pathogen requires free moisture to release ascospores from its cleistothecia in the spring. However, free moisture is not needed for secondary spread via conidia; high atmospheric humidity is sufficient. Its anamorph is called Oidium tuckeri.

<i>Diplocarpon rosae</i> Species of fungus

Diplocarpon rosae is a fungus that creates the rose black spot disease. Because it was observed by people of various countries around the same time, the nomenclature for the fungus varied with about 25 different names. The asexual stage is now known to be Marssonina rosae, while the sexual and most common stage is known as Diplocarpon rosae.

<i>Venturia inaequalis</i> Species of fungus

Venturia inaequalis is an ascomycete fungus that causes the apple scab disease.

Dead arm of grapevine

Dead arm, sometimes grape canker, is a disease of grapes caused by a deep-seated wood rot of the arms or trunk of the grapevine. As the disease progresses over several years, one or more arms may die, hence the name "dead arm". Eventually the whole vine will die. In the 1970s, dead-arm was identified as really being two diseases, caused by two different fungi, Eutypa lata and Phomopsis viticola.

<i>Monilinia fructicola</i> Species of fungus

Monilinia fructicola is a species of fungus in the order Helotiales. A plant pathogen, it is the causal agent of brown rot of stone fruits.

<i>Gymnosporangium juniperi-virginianae</i>

Gymnosporangium juniperi-virginianae is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples (Malus) and Eastern red-cedar coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars. Quince and hawthorn are the most common host and many species of juniper can substitute for the eastern red cedars.

<i>Monilinia laxa</i> Species of fungus

Monilinia laxa is a plant pathogen that is the causal agent of brown rot of stone fruits.

<i>Podosphaera leucotricha</i> Species of fungus

Podosphaera leucotricha is a plant pathogen that can cause powdery mildew of apples and pears.

<i>Taphrina deformans</i> Species of fungus

Taphrina deformans is a fungus and plant pathogen, and a causal agent[s] of peach leaf curl. Peach trees infected with T. deformans will experience leaf puckering and distortion, acquiring a characteristic downward and inward curl. Leaves will also undergo chlorosis, turning a pale green or yellow, and later show a red or purple tint. Fruit can either drop prematurely or show surface distortions. Severe infection can also produce lesions on the flowers. The host tree will experience defoliation if the leaves are badly diseased. If a seedling is severely infected, it may die. Almond trees display similar symptoms.

<i>Oidium mangiferae</i> Species of fungus

Oidium mangiferae is a plant pathogen that infects mango trees causing powdery mildew. Powdery mildew of mango is an Ascomycete pathogen of the Erysiphales family that was initially described by Berthet in 1914, using samples collected from Brazil. O. mangiferae is found in all areas where mangoes have been raised long term, but is particularly widespread in India where both the host and the pathogen are native. Currently no teleomorph stage has been identified, but due to certain morphological characteristics it has been suggested that O. mangiferae belongs in the Erysiphe polygony group. Mango is the only known host for this pathogen, though O. mangiferae appears to be identical to fungi responsible for powdery mildew diseases on various other plant species, particularly oak, though some differences may be observed. In particular, the number of cells in conidiophores varies from 2 on mango to 3-5 on oak. O. mangiferae has been known to infect oak leaves in the laboratory, however due to the lack of a known telemorph stage O. mangiferae is still considered to only be a pathogen of mango. Recent analysis of its ribosomal DNA suggests it is conspecific with Erysiphe alphitoides, the causative agent of powdery mildew in European oaks.

<i>Elsinoë ampelina</i> Species of fungus

Elsinoë ampelina is a plant pathogen, which is the causal agent of anthracnose on grape.

<i>Dibotryon morbosum</i> Species of fungus

Dibotryon morbosum or Apiosporina morbosa is a plant pathogen, which is the causal agent of black knot. It affects cherry, plum, apricot and chokecherry trees in North America. The disease produces rough, black growths that encircle and kill the infested parts, and provide habitat for insects.

<i>Taphrina pruni</i> Species of fungus

Taphrina pruni is a fungal plant pathogen of blackthorn that causes the pocket or bladder plum gall, a chemically induced distortion of the fruit (sloes), producing swollen on one side, otherwise deformed and flattened fruit gall without a stone. The twigs on infected plants may also be deformed with small strap-shaped leaves.

<i>Taphrina caerulescens</i> Species of fungus

Taphrina caerulescens is a species of fungus in the family Taphrinaceae. It is a pathogenic Ascomycete fungus that causes oak leaf blister disease on various species of oak trees. The associated anamorph species is Lalaria coccinea, described in 1990. This disease causes lesions and blisters on Oak leaves. Effects of the disease are mostly cosmetic. Although not taxonomically defined, strains of T. caerulescens have been shown to be host specific with varying ¬ascus morphology between strains. There are differences in strains’ abilities to metabolize various carbon and nitrogen compounds. This has been proposed as a method of taxonomically defining subspecies within T. caerulescens.

Leucostoma canker is a fungal disease that can kill stone fruit. The disease is caused by the plant pathogens Leucostoma persoonii and Leucostoma cinctum (teleomorph) and Cytospora leucostoma and Cytospora cincta (anamorphs). The disease can have a variety of signs and symptoms depending on the part of the tree infected. One of the most lethal symptoms of the disease are the Leucostoma cankers. The severity of the Leucostoma cankers is dependent on the part of the plant infected. The fungus infects through injured, dying or dead tissues of the trees. Disease management can consist of cultural management practices such as pruning, late season fertilizers or chemical management through measures such as insect control. Leucostoma canker of stone fruit can cause significant economic losses due to reduced fruit production or disease management practices. It is one of the most important diseases of stone fruit tree all over the world.

Peach scab, also known as peach freckles, is a disease of stone fruits caused by the fungi Cladosporium carpophilum. The disease is most prevalent in wet and warm areas especially southern part of the U.S. as the fungi require rain and wind for dispersal. The fungus causes scabbing, lesions, and defoliating on twig, fruit, and leaf resulting in downgrade of peach quality or loss of fruits due to rotting in severe cases.

Cherry leaf spot Plant fungal disease

Cherry leaf spot is a fungal disease which infects cherries and plums. Sweet, sour, and ornamental cherries are susceptible to the disease, being most prevalent in sour cherries. The variety of sour cherries that is the most susceptible are the English morello cherries. This is considered a serious disease in the Midwest, New England states, and Canada. It has also been estimated to infect 80 percent of orchards in the Eastern states. It must be controlled yearly to avoid a significant loss of the crop. If not controlled properly, the disease can dramatically reduce yields by nearly 100 percent. The disease is also known as yellow leaf or shothole disease to cherry growers due to the characteristic yellowing leaves and shot holes present in the leaves upon severe infection.

Cladosporium fulvum is an Ascomycete called Passalora fulva, a non-obligate pathogen that causes the disease on tomato known as the Tomato leaf mold. P. fulva only attacks tomato plants, especially the foliage, and it is a common disease in greenhouses, but can also occur in the field. The pathogen is likely to grow in humid and cool conditions. In greenhouses, this disease causes big problems during the fall, in the early winter and spring, due to the high relative humidity of air and the temperature, that are propitious for the leaf mold development. This disease was first described in the North Carolina, by Mordecai Cubitt Cooke (1883), on cultivated tomato, although it is originally from South and Central America. The causal fungus of tomato leaf mold may also be referred to as Cladosporium fulvum, a former name.

Shot hole disease Fungal disease of plants

Shot hole disease is a serious fungal disease that creates BB-sized holes in leaves, rough areas on fruit, and concentric lesions on branches. The pathogen that causes shot hole disease is Wilsonomyces carpophilus.

<i>Botrytis squamosa</i> Species of fungus

Botrytis squamosa is a fungus that causes leaf blight on onion that is distinctly characterized by the two stages – leaf spotting followed by blighting. The pathogen is an ascomycete that belongs to the family Sclerotiniaceae in the order Helotiales. The lesions start out as whitish streaks and take on a yellow tinge as they mature. They cause yield losses up to 30%. This fungus is endemic to the USA and has also been reported in Europe, Asia, and Australia. Typical management of this disease includes chemical fungicides with significant efforts being made to establish a means of biological control.

References

  1. ↑ "Peach leaf curl, Taphrina deformans". West Virginia University. Archived from the original on 2007-08-29.
  2. 1 2 3 Gray, William D. (1959). The Relation of Fungi to Human Affairs. New York: Henry Holt and Company, Inc.
  3. 1 2 3 Chester, Kenneth Starr (1947). Nature and Prevention of Plant Diseases (2nd ed.). Philadelphia: The Blakiston Company.
  4. ↑ Hessayon, D.G. (2004). The Fruit Expert. London: Expert Books.
  5. ↑ Munkvold, Gary P. (2001). "Eutypa Dieback of Grapevine and Apricot". Plant Health Progress. 2: 9. doi:10.1094/PHP-2001-0219-01-DG.
  6. ↑ Kövics, György J. (2011). "A Taphrina deformans különleges előfordulása kajszin, Magyarországon" [An unusual occurrence of Taphrina deformans on apricot trees in Hungary]. Acta Agraria Debreceniensis (in Hungarian) (43): 86–92.
  7. ↑ Rossi, V.; Bolognesi, M.; Languasco, L.; Giosuè, S. (2006). "Influence of Environmental Conditions on Infection of Peach Shoots by Taphrina deformans". Phytopathology. Scientific Societies. 96 (2): 155–163. doi: 10.1094/phyto-96-0155 . ISSN   0031-949X. PMID   18943918.
  8. 1 2 3 "Peach Leaf Curl Management Guidelines". ipm.ucdavis.edu. 2005-05-20.
  9. ↑ "Peach leaf curl". Royal Horticultural Society. Archived from the original on 2013-01-11.
  10. ↑ Pscheidt, Jay W. (Jan 1, 2009). "Peach--Leaf Curl". An Online Guide to Plant Disease Control. Oregon State University. Archived from the original on June 12, 2010..
  11. ↑ "Kräuselkrankheit: Befall an allen Pfirsichsorten". lwg.bayern.de (in German). Archived from the original on 2013-06-20.
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