Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.
Panama disease is a plant disease that infects banana plants. It is a wilting disease caused by the fungus Fusarium oxysporum f. sp. cubense (Foc). The pathogen is resistant to fungicides and its control is limited to phytosanitary measures.
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.
Stewart's wilt is a bacterial disease of corn caused by the bacterium Pantoea stewartii. The disease is also known as bacterial wilt or bacterial leaf blight and has been shown to be quite problematic in sweet corn. The causal organism is a facultatively anaerobic, gram-negative, rod-shaped bacterium. The disease is endemic in the mid-Atlantic and Ohio River Valley regions and in the southern portion of the Corn Belt. Stewart's Wilt causes minor reductions in field corn yield, despite common occurrence, because most hybrids grown in the Midwest have adequate resistance. However, the disease can be problematic in seed production because many countries have restrictions on maize seed from areas where the Stewart's Wilt occurs.
Verticillium is a genus of fungi in the division Ascomycota, and are an anamorphic form of the family Plectosphaerellaceae. The genus used to include diverse groups comprising saprobes and parasites of higher plants, insects, nematodes, mollusc eggs, and other fungi, thus the genus used to have a wide-ranging group of taxa characterised by simple but ill-defined characters. The genus, currently thought to contain 51 species, may be broadly divided into three ecologically based groups - mycopathogens, entomopathogens, and plant pathogens and related saprotrophs. However, the genus has undergone recent revision into which most entomopathogenic and mycopathogenic isolates fall into a new group called Lecanicillium.
Verticillium wilt is a wilt disease affecting over 350 species of eudicot plants. It is caused by six species of Verticillium fungi: V. dahliae, V. albo-atrum, V. longisporum, V. nubilum, V. theobromae and V. tricorpus. Many economically important plants are susceptible including cotton, tomatoes, potatoes, oilseed rape, eggplants, peppers and ornamentals, as well as others in natural vegetation communities. Many eudicot species and cultivars are resistant to the disease and all monocots, gymnosperms and ferns are immune.
Ophiostoma ulmi is a species of fungus in the family Ophiostomataceae. It is one of the causative agents of Dutch elm disease. It was first described under the name Graphium ulmi, and later transferred to the genus Ophiostoma.
Ralstonia solanacearum is an aerobic non-spore-forming, Gram-negative, plant pathogenic bacterium. R. solanacearum is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants. It is known as Granville wilt when it occurs in tobacco. Bacterial wilts of tomato, pepper, eggplant, and Irish potato caused by R. solanacearum were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen. Because of its devastating lethality, R. solanacearum is now one of the more intensively studied phytopathogenic bacteria, and bacterial wilt of tomato is a model system for investigating mechanisms of pathogenesis. Ralstonia was until recently classified as Pseudomonas, with similarity in most aspects, except that it does not produce fluorescent pigment like Pseudomonas. The genomes from different strains vary from 5.5 Mb up to 6 Mb, roughly being 3.5 Mb of a chromosome and 2 Mb of a megaplasmid. While the strain GMI1000 was one of the first phytopathogenic bacteria to have its genome completed, the strain UY031 was the first R. solanacearum to have its methylome reported. Within the R. solanacearum species complex, the four major monophyletic clusters of strains are termed phylotypes, that are geographically distinct: phylotypes I-IV are found in Asia, the Americas, Africa, and Oceania, respectively.
Ophiostoma novo-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the key causative agents associated with Dutch Elm Disease (DED), along with Ophiostoma ulmi and Ophiostoma himal-ulmi.
Phialophora gregata is a Deuteromycete fungus that is a plant pathogen which causes the disease commonly known as brown stem rot of soybean. P. gregata does not produce survival structures, but has the ability to overwinter as mycelium in decaying soybean residue.
Bacterial wilt is a complex of diseases that occur in plants such as Cucurbitaceae and Solanaceae and are caused by the pathogens Erwinia tracheiphila, a gram-negative bacterium, or Curtobacterium flaccumfaciens pv. flaccumfaciens, a gram-positive bacterium. Cucumber and melon plants are most susceptible, but squash, pumpkins, and gourds may also become infected.
Bursaphelenchus xylophilus, commonly known as pine wood nematode or pine wilt nematode (PWN), is a species of nematode that infects trees in the Pinus genus of coniferous trees and causes the disease pine wilt. While native to North America, it spread in the early 20th century to Japan and in the latter half of the century to other areas of Asia, including China, Taiwan, and Korea, as well as to Europe, including Portugal and Spain.
Plant disease epidemiology is the study of disease in plant populations. Much like diseases of humans and other animals, plant diseases occur due to pathogens such as bacteria, viruses, fungi, oomycetes, nematodes, phytoplasmas, protozoa, and parasitic plants. Plant disease epidemiologists strive for an understanding of the cause and effects of disease and develop strategies to intervene in situations where crop losses may occur. Destructive and non-destructive methods are used to detect diseases in plants. Additionally, understanding the responses of the immune system in plants will further benefit and limit the loss of crops. Typically successful intervention will lead to a low enough level of disease to be acceptable, depending upon the value of the crop.
Forest pathology is the research of both biotic and abiotic maladies affecting the health of a forest ecosystem, primarily fungal pathogens and their insect vectors. It is a subfield of forestry and plant pathology.
Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs. The most common hosts of the pathogen include slash pine, loblolly pine, Monterey pine, Mexican weeping pine, and Douglas fir. Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.
Beet vascular necrosis and rot is a soft rot disease caused by the bacterium Pectobacterium carotovorum subsp. betavasculorum, which has also been known as Pectobacterium betavasculorum and Erwinia carotovora subsp. betavasculorum. It was classified in the genus Erwinia until genetic evidence suggested that it belongs to its own group; however, the name Erwinia is still in use. As such, the disease is sometimes called Erwinia rot today. It is a very destructive disease that has been reported across the United States as well as in Egypt. Symptoms include wilting and black streaks on the leaves and petioles. It is usually not fatal to the plant, but in severe cases the beets will become hollowed and unmarketable. The bacteria is a generalist species which rots beets and other plants by secreting digestive enzymes that break down the cell wall and parenchyma tissues. The bacteria thrive in warm and wet conditions, but cannot survive long in fallow soil. However, it is able to persist for long periods of time in the rhizosphere of weeds and non-host crops. While it is difficult to eradicate, there are cultural practices that can be used to control the spread of the disease, such as avoiding injury to the plants and reducing or eliminating application of nitrogen fertilizer.
Koa wilt is a relatively new disease to Hawaii, discovered in 1980. Koa wilt is caused by a forma specialis of the fungus Fusarium oxysporum, which is now abundant in Hawaiian soils and infects the native Acacia koa tree, a once-dominant species in the canopy of Hawaiian forests. Fusarium oxysporum f.sp. koae is believed to have been brought into Hawaii on an ornamental acacia plant. Fusarium fungi clog the tree xylem, causing significant wilt and mortality among these beautiful and iconic Hawaiian trees.
Species which are not native to a forest ecosystem can act as an agent of disturbance, changing forest dynamics as they invade and spread. Invasive insects and pathogens (diseases) are introduced to the United States through international trade, and spread through means of natural and human-dispersal. Invasive insects and pathogens are a serious threat to many forests in the United States and have decimated populations of several tree species, including American chestnut, American elm, eastern hemlock, whitebark pine, and the native ash species. The loss of these tree species is typically rapid with both short and long-term impacts to the forest ecosystem.
Vascular wilt in the perennial shrub lulo or naranjilla is a disease caused by the fungus Fusarium oxysporum f. sp. quitoense.
Coffee wilt disease (tracheomycosis) is a common wilt that results in complete death of coffee trees it infects. This vascular disease is induced by the fungal pathogen known by its teleomorph Gibberella xylarioides. In 1927, coffee wilt disease (CWD) was first observed in the Central African Republic where it developed slowly and went on to cause two epidemics between the 1930s and the 1960s. Coffee wilt disease was first seen in Coffea excelsa.
