| Pseudopezicula tetraspora | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Leotiomycetes |
| Order: | Helotiales |
| Family: | Helotiaceae |
| Genus: | Pseudopezicula |
| Species: | P. tetraspora |
| Binomial name | |
| Pseudopezicula tetraspora Korf, R.C. Pearson & W.Y. Zhuang (1986) | |
Pseudopezicula tetraspora is a species of fungus in the family Helotiaceae. Found in North America, it is a plant pathogen that infects grape, causing a disease known as "angular leaf scorch". [1]
The hosts of P. tetraspora include some plants of the family Vitaceae. Angular leaf scorch of grapevines has been observed on 18 species of grapevines Vitis, on interspecific hybrids of Vitis, and on Virginia creeper Parthenocissus quiniquefolia. [2] An early symptom of angular leaf scorch of grapevines is the presence of faint chlorotic lesions near major veins on the leaf surface. [3] As the disease progresses, the lesions spread, changing from yellow to reddish brown. Reddening/browning of major leaf veins accompanies the lesions. The reddish brown tissue turns necrotic and retains a yellow margin, which separates the necrotic tissue from the healthy tissue. [3] In red or black Vitis cultivars, the margin is read, not yellow [2] and on occasion, the yellow margin is not present. The reddish brown lesions with yellow margins can be seen in early June or three to four weeks after infection begins. [3] As the lesions become larger late in the growing season, necrosis can cause premature defoliation, thus inhibiting photosynthesis of the plant host. Flower clusters can also dry prematurely, which decreases the plant's ability to produce fruit. [2]
Pseudopezicula tetraspora fungi overwinter in leaf litter on the soil surface. If there is sufficient moisture in the spring, fruiting bodies (apothecia) form and produce asci. The asci produce four ascospores each by sexual reproduction. Ascospores are forcibly released from the asci at the end of a rain event following a dry period and are splashed by water or carried by wind to host leaves and flower stems. [3] When the ascospores reach the host plant, the infection cycle begins. There is usually one cycle per growing season which takes place during the spring, but if moist conditions continue throughout the growing season, apothecia can form on dead tissue of infected leaves that are still attached to the plant host. [4] Asci with ascospores are produced from the apothecia and the ascospores re-infect the same host or other susceptible hosts.[ citation needed ]
Cultural practices and fungicide use are two methods that grape growers use to reduce P. tetraspora. Removing leaf litter, increasing air circulation over the soil surface and canopy space, and removal of susceptible hosts from the immediate environment are some cultural practices that can help control P. tetraspora development. Because P. tetraspora survives on leaf litter, the removal of the litter before bud break can remove residual P. tetraspora. [3] Apothecia of P. tetraspora require moisture to germinate and ascospores require moisture for dispersal, so increasing air circulation to the soil surface will detour P. tetraspora from getting to the host. [3] Removal of other susceptible hosts of the family Vitaceae, like Parthenocissus quiniquefolia can reduce the likelihood of foreign P. tetraspora inoculum to enter where one doesn't want disease. [3] Foliar fungicide sprays are recommended to control P. tetraspora because the ascospore lands on, infects, and penetrates the leaf. Products containing the fungicide mancozeb are generally used as a foliar spray for P. tetraspora control. Mancozeb disturbs the ascospores when they land on the plant tissue treated with the product. [5]
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to the Peronosporaceae family. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines. The prime example is Peronospora farinosa featured in NCBI-Taxonomy and HYP3. This pathogen does not produce survival structures in the northern states of the United States, and overwinters as live mildew colonies in Gulf Coast states. It progresses northward with cucurbit production each spring. Yield loss associated with downy mildew is most likely related to soft rots that occur after plant canopies collapse and sunburn occurs on fruit. Cucurbit downy mildew only affects leaves of cucurbit plants.
Apple scab is a common disease of plants in the rose family (Rosaceae) that is caused by the ascomycete fungus Venturia inaequalis. While this disease affects several plant genera, including Sorbus, Cotoneaster, and Pyrus, it is most commonly associated with the infection of Malus trees, including species of flowering crabapple, as well as cultivated apple. The first symptoms of this disease are found in the foliage, blossoms, and developing fruits of affected trees, which develop dark, irregularly-shaped lesions upon infection. Although apple scab rarely kills its host, infection typically leads to fruit deformation and premature leaf and fruit drop, which enhance the susceptibility of the host plant to abiotic stress and secondary infection. The reduction of fruit quality and yield may result in crop losses of up to 70%, posing a significant threat to the profitability of apple producers. To reduce scab-related yield losses, growers often combine preventive practices, including sanitation and resistance breeding, with reactive measures, such as targeted fungicide or biocontrol treatments, to prevent the incidence and spread of apple scab in their crops.
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.
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.
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”.
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.
Venturia inaequalis is an ascomycete fungus that causes the apple scab disease.
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.
Diplocarpon earlianum is a species of fungus that causes disease in strawberry plants called strawberry leaf scorch. The disease overwinters in plant debris and infects strawberry plants during the spring season when it is wet. The five main methods to reduce strawberry leaf scorch include: irrigation techniques, crop rotation, planting resistant and disease-free seeds, fungicide use, and sanitation measures. Control of strawberry leaf scorch is important because it is responsible for the majority of disease in strawberries. Diplocarpon earliana affects the fruit quality and yield of the strawberry crop. Losses range from negligible to severe depending on numerous epidemiological factors including cultivar susceptibility, type of cropping system, and weather conditions
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.
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.
Pseudopezicula is a genus of fungi in the family Helotiaceae. Circumscribed by mycologist Richard Korf in 1986, the genus contains two species that cause angular leaf scorch disease on grapes.
This article summarizes different crops, what common fungal problems they have, and how fungicide should be used in order to mitigate damage and crop loss. This page also covers how specific fungal infections affect crops present in the United States.
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.
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.
Banana freckle is a disease caused by the fungus Guignardia musae (teleomorph) or Phyllosticta musarum (anamorph). Generally, the causal agent of disease is referred to as Guignardia-Phyllosticta sp. There are several different strains of the fungus that exist to infect different banana varieties around the globe. Symptoms include yellowing of the tissue and formation of small dark brown spots on the leaves and fruit. Within the spots, conidia or pycnidia can be found. Banana freckle is easily propagated and spread from plant to plant by rain splash and movement of infected tissue or fruit. Management of the disease consists of cutting out infected leaves, using the paper bag method, fungicide application, and proper sanitation techniques it can be stopped by applying vegeta to it. This devastating disease is extremely relevant for the major banana exporting countries of the world. In the absence of chemical control, there is about a 78% yield loss. Banana freckle disease needs to be carefully monitored in order to prevent further spread of the disease.
Botryotinia polyblastis is a fungal plant pathogen that causes Narcissus Fire of daffodils, genus Narcissus.
Phakopsora euvitis is a rust fungus that causes disease of grape leaves. This rust fungus has been seen in regions including: Eastern Asia, Southern Asia, Southwestern Brazil, the Americas, and northern Australia. It is widely distributed in eastern and southern Asia but was first discovered on grapevines in Darwin, Australia in 2001 and was identified as Asian grapevine leaf rust by July 2007.