Phomopsis cane and leaf spot | |
---|---|
Common names | Phomopsis cane and leaf spot |
Causal agents | Phomopsis viticola |
Hosts | Vine, Prunus , apples, pears, walnuts, pistachios |
EPPO Code | PHOPVI |
Distribution | Australia, United States, Canada, Japan, Sud Africa |
Phomopsis cane and leaf spot occurs wherever grapes are grown. Phomopsis cane and leaf spot is more severe in grape-growing regions characterized by a humid temperate climate through the growing season. Crop losses up to 30% have been reported to be caused by Phomopsis cane and leaf spot. [1]
Phomopsis cane and leaf spot is a disease that causes symptoms in the common grapevine species, Vitis vinifera, in many regions of the world. [2] This disease is mainly caused by the fungal pathogen, Phomopsis viticola, and is known to affect many cultivars of table grapes, such as Thompson Seedless, Red Globe, and Flame Seedless. [3] Also in vines of oenological interest, such as Cabernet Sauvignon, Zinfandel, Syrah, Barbera, Chardonnay and Merlot. [4] Spots or lesions on shoots and leaves are common symptoms of the disease. Small, black spots on the internodes at the base of developing shoots are probably the most common disease symptom. These spots are usually found on the first three to four basal internodes. The spots may develop into elliptical lesions that may grow together to form irregular, black, crusty areas. Under severe conditions, shoots may split and form longitudinal cracks. Although cane lesions often appear to result in little damage to the vines, it is important to remember that these lesions are the primary source of overwintering inoculum for the next growing season. Leaf infections first appear as small, light-green spots with irregular, occasionally star-shaped margins. Usually only the lower one to four leaves on a shoot are affected. In time, the spots become larger, turn black, and have a yellow margin . Leaves become distorted and die if large numbers of lesions develop. Infections of leaf petioles may cause leaves to turn yellow and fall off. All parts of the grape cluster (berries and rachises or cluster stems) are susceptible to infection throughout the growing season; however, most infections appear to occur early in the growing season. Lesions developing on the first one or two cluster stems (rachises) on a shoot may result in premature withering of the cluster stem. Infected clusters that survive until harvest often produce infected or poor-quality fruit. [5] Soil moisture and temperature can impact the severity of symptoms, leading to a systemic infection in warm and wet conditions.
Phomopsis cane and leaf spot is caused by an ascomycete fungal plant pathogen. [6] This pathogen produces sexual spores (ascospores) in the teleomorph stage and asexual spores (conidia) during the anamorph stage. [7] Phomopsis (Sacc.) Bubák (teleomorph: Diaporthe Nitschke) is a cosmopolitan fungal genus that contains both plant pathogens and endophytes described from a wide range of annual and perennial hosts, including economically important crops. [4]
The teleomorph stage of the disease cycle does not occur in nature and involves sexual combination of the antheridium with the ascogonium to produce ascospores, allowing for genetic variation. [8] The ascospores are encased in an ascus, which is further protected in a survival structure called the perithecium. [9] Ascospores can be dispersed over long distances in the wind, but can also be mechanically transmitted or disseminated in rain. The anamorph stage is known to occur in nature and produces the main inoculum associated with this plant pathogen. [8] During favorable conditions, conidia are released from infected lesions on the leaves or fruit and dispersed to other plants through rainfall or wind. Pre-existing wounds on the plant from annual pruning or insects allow the pathogen to gain entry into the next plant. However, if wounds are not present, the conidia can germinate to produce an appressorium to directly penetrate the plant. [9] Once new plants are infected, conidia are produced throughout the season as the secondary cycle of this polycyclic disease. Phomopsis viticola overwinters as pycnidia until favorable conditions arise again. [9]
The severity of Phomopsis cane and leaf spot in grapevine varies greatly between growing seasons. Fungal pathogens depend on moist conditions, causing the intensity of disease outbreaks to increase in wet environments. As the amount of rainfall changes between the seasons, so does the amount of pathogen present in the field. Prolonged rainfall early in the season has been correlated with greater disease outbreak. [9] Temperature has also been shown to influence the infection rate. It has been found that the pathogen experiences the fastest rate of reproduction between 23 and 25 °C (73 and 77 °F). [9] Although temperature is important, the amount of rainfall has a greater impact on this pathogen because rainfall is an effective method of conidial dispersal. The conidia of Phomopsis viticola can also be dispersed through sprinkler irrigation and agricultural runoff. [10] It has not yet been determined if an insect vector for this pathogen exists. [10]
Sulforix is recommended from delayed dormancy through to bud swell. [11]
Eutypa dieback, also known as dead arm, is caused by Eutypa lata (synonym: Eutypa armeniacae) which infects fresh pruning wounds when there is adequate moisture on the vine, such as just after a rain. The fungus also attacks many other hosts such as cherry trees, most other Prunus species, as well as apples, pears and walnuts.
Grape black rot is a fungal disease caused by an ascomycetous fungus, Guignardia bidwellii, that attacks grape vines during hot and humid weather. “Grape black rot originated in eastern North America, but now occurs in portions of Europe, South America, and Asia. It can cause complete crop loss in warm, humid climates, but is virtually unknown in regions with arid summers.” The name comes from the black fringe that borders growing brown patches on the leaves. The disease also attacks other parts of the plant, “all green parts of the vine: the shoots, leaf and fruit stems, tendrils, and fruit. The most damaging effect is to the fruit”.
Leptosphaeria coniothyrium is a plant pathogen. It can be found around the world.
Pyrenophora tritici-repentis (teleomorph) and Drechslera tritici-repentis (anamorph) is a necrotrophic plant pathogen of fungal origin, phylum Ascomycota. The pathogen causes a disease originally named yellow spot but now commonly called tan spot, yellow leaf spot, yellow leaf blotch or helminthosporiosis. At least eight races of the pathogen are known to occur based on their virulence on a wheat differential set.
Lasiodiplodia theobromae is a plant pathogen with a very wide host range. It causes rotting and dieback in most species it infects. It is a common post harvest fungus disease of citrus known as stem-end rot. It is a cause of bot canker of grapevine. It also infects Biancaea sappan, a species of flowering tree also known as Sappanwood.
Botryosphaeria ribis is a fungal plant pathogen that infects many trees causing cankers, dieback and death.
Diaporthe helianthi is a fungal pathogen that causes Phomopsis stem canker of sunflowers. In sunflowers, Phomopsis helianthi is the causative agent behind stem canker. Its primary symptom is the production of large canker lesions on the stems of sunflower plants. These lesions can eventually lead to lodging and plant death. This disease has been shown to be particularly devastating in southern and eastern regions of Europe, although it can also be found in the United States and Australia. While cultural control practices are the primary method of controlling for Stem Canker, there have been a few resistant cultivars developed in regions of Europe where the disease is most severe.
Mycosphaerella angulata is a fungal plant pathogen infecting muscadine grapes. This pathogen causes the common disease angular leaf spot. Mycosphaerella angulate is an ascomycete in the fungi kingdom.
Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather the lesions sporulate and new secondary infections occur.
Phomopsis obscurans is a common fungus found in strawberry plants, which causes the disease of leaf blight. Common symptoms caused by the pathogen begin as small circular reddish-purple spots and enlarge to form V-shaped lesions that follow the vasculature of the plant's leaves. Although the fungus infects leaves early in the growing season when the plants are beginning to develop, leaf blight symptoms are most apparent on older plants towards the end of the growing season. The disease can weaken strawberry plants through the destruction of foliage, which results in reduced yields. In years highly favorable for disease development, leaf blight can ultimately lead to the death of the strawberry plants. A favorable environment for the growth and development of the Phomopsis obscurans pathogen is that of high temperature, high inoculum density, a long period of exposure to moisture, and immature host tissue. In the case of disease management, a conjunction of cultural practices is the most effective way of reducing the infection.
Glomerella cingulata is a fungal plant pathogen, being the name of the sexual stage (teleomorph) while the more commonly referred to asexual stage (anamorph) is called Colletotrichum gloeosporioides. For most of this article the pathogen will be referred to as C. gloeosporioides. This pathogen is a significant problem worldwide, causing anthracnose and fruit rotting diseases on hundreds of economically important hosts.
Elsinoë ampelina is a plant pathogen, which is the causal agent of anthracnose on grape.
Cercospora sojina is a fungal plant pathogen which causes frogeye leaf spot of soybeans. Frog eye leaf spot is a major disease on soybeans in the southern U.S. and has recently started to expand into the northern U.S. where soybeans are grown. The disease is also found in other soybean production areas of the world.
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Southern corn leaf blight (SCLB) is a fungal disease of maize caused by the plant pathogen Bipolaris maydis.
Raspberry leaf spot is a plant disease caused by Sphaerulina rubi, an ascomycete fungus. Early symptoms of infection are dark green spots on young leaves. As the disease progresses, these spots turn tan or gray in color. Disease management strategies for raspberry leaf spots include the use of genetically resistant raspberry plant varieties, chemical fungicide sprays, and cultural practices such as pruning and thinning out canes.
Common spot of strawberry is one of the most common and widespread diseases afflicting the strawberry. Common spot of strawberry is caused by the fungus Mycosphaerella fragariae. Symptoms of this disease first appear as circular, dark purple spots on the leaf surface. Mycosphaerella fragariae is very host-specific and only infects strawberry.
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.
Gummy stem blight is a cucurbit-rot disease caused by the fungal plant pathogen Didymella bryoniae. Gummy stem blight can affect a host at any stage of growth in its development and affects all parts of the host including leaves, stems and fruits. Symptoms generally consist of circular dark tan lesions that blight the leaf, water soaked leaves, stem cankers, and gummy brown ooze that exudes from cankers, giving it the name gummy stem blight. Gummy stem blight reduces yields of edible cucurbits by devastating the vines and leaves and rotting the fruits. There are various methods to control gummy stem blight, including use of treated seed, crop rotation, using preventative fungicides, eradication of diseased material, and deep plowing previous debris.
Grapevine trunk diseases (GTD) are the most destructive diseases of vineyards worldwide. Fungicides with the potential to control GTD have been banned in Europe and there are no highly effective treatments available. Action to develop new strategies to fight these diseases are needed.
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.
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