Bacterial soft rots are caused by several types of bacteria, but most commonly by species of gram-negative bacteria, "Erwinia", "Pectobacterium", and "Pseudomonas". It is a destructive disease of fruits, vegetables, and ornamentals found worldwide, and effects genera from nearly all the plant families. The bacteria mainly attack the fleshy storage organs of their hosts (tubers, corms, bulbs, and rhizomes), but they also affect succulent buds, stems, and petiole tissues. With the aid of special enzymes, the plant is turned into a liquidy mush in order for the bacteria to consume the plant cell's nutrients. Disease spread can be caused by simple physical interaction between infected and healthy tissues during storage or transit. The disease can also be spread by insects. Control of the disease is not always very effective, but sanitary practices in production, storing, and processing are something that can be done in order to slow the spread of the disease and protect yields.

The disease can infect trees as young as 6 years-old, and infects trees throughout their lifespan. Diagnostic symptoms include crown yellowing and thinning, a distress crop of cones, red brown stained outer heartwood, and laminate decay (decay that separates along annual rings). The disease tends to occur in patches due to a primarily short range spread mechansism. Infected or decayed roots break close to the root collar forming “root balls.” Laminated root rot is frequently detected during ground survey when canopy openings and standing dead and fallen trees are observed. Signs of laminated root rot include the setal hyphae (tiny hairlike hyphae) between sheets of decomposing wood and also buff-colored mycelium on the outside of the roots.

Laminated root rot also known as yellow ring rot is caused by the fungal pathogen "Phellinus weirii". Laminated root rot is one of the most damaging root disease amongst conifers in northwestern America and true firs, Douglas-fir, Mountain hemlock, and Western hemlock are highly susceptible to infection with "P. weirii". A few species of plants such as Western white pine and Lodgepole pine are tolerant to the pathogen while Ponderosa pine is resistant to it. Only hardwoods are known to be immune to the pathogen.

Armillaria root rot is a fungal root rot caused by several different members of the genus "Armillaria". The symptoms are variable depending on the host infected, ranging from stunted leaves to chlorotic needles and dieback of twigs and branches. However, all infected hosts display symptoms characteristic of being infected by a white rotting fungus. The most effective ways of management focus on limiting the spread of the fungus, planting resistant species, and removing infected material. This disease poses a threat to the lumber industry as well as affecting recreational areas.

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" (syn. "Cryptosporella viticola").

There are a variety of hosts including but not limited to; banana, beans, cabbage, carrot, cassava, coffee, corn, cotton, onion, other crucifers, pepper, potato, sweet potato and tomato. For each host there are different symptoms displayed. Most symptoms are along the lines of watery and soft decay of the tissue. Cabbage and crucifers' symptoms start where the tissue makes contact with the soil. Often there is a change in color and in the case of a carrot, the whole taproot can be decayed leaving just the epidermis. Sweet potatoes show clear lesions that grow rapidly leaving a recognizable watery and soft, oozy tissue where only the peel remains intact.

Potatoes experience a cream to tan colored tuber that becomes very soft and watery. A characteristic black border separates the diseased area and the healthy tissue. Only when the secondary organism invades the infected tissue does that decay become slimy with a foul odor. Like the carrot, the whole tuber can be consumed leaving just the epidermis in the soil. The foliage becomes weak and chlorotic with upward turned leaves and lesions on the stem. The stem also rots and becomes mushy with its colorless or brown lesions.

Dead arm is a disease that causes symptoms in the common grapevine species, "vitis vinifera", in many regions of the world. 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. Early in the growing season, the disease can delay the growth of the plant and cause leaves to turn yellow and curl. Small, brown spots on the shoots and leaf veins are very common first symptoms of this disease. Soil moisture and temperature can impact the severity of symptoms, leading to a systemic infection in warm, wet conditions. As the name of this disease suggests, it also causes one or more arms of the grapevine to die, often leading to death of the entire vine.

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.

Ascochyta blights occur throughout the world and can be of significant economic importance. Three fungi contribute to the ascochyta blight disease complex of pea ("Pisum sativum"). "Ascochyta pinodes" (sexual stage: "Mycosphaerella pinodes") causes Mycosphaerella blight. "Ascochyta pinodella" (synonym: "Phoma medicaginis" var. "pinodella") causes Ascochyta foot rot, and "Ascochyta pisi" causes Ascochyta blight and pod spot. Of the three fungi, "Ascochyta pinodes" is of the most importance. These diseases are conducive under wet and humid conditions and can cause a yield loss of up to fifty percent if left uncontrolled. The best method to control ascochyta blights of pea is to reduce the amount of primary inoculum through sanitation, crop-rotation, and altering the sowing date. Other methods—chemical control, biological control, and development of resistant varieties—may also be used to effectively control ascochyta diseases.

Diseases can have a variety of causes, including bacterial infections from an external source such as "Pseudomonas fluorescens" (causing fin rot and fish dropsy), fungal infections (Saprolegnia), mould infections (Oomycete and "Saprolegnia"), parasitic disorders ("Gyrodactylus salaris", "Ichthyophthirius multifiliis", Cryptocaryon, Oodinium causing velvet disease, "Brooklynella hostilis", head and lateral line erosion, Glugea, "Ceratomyxa shasta", "Kudoa thyrsites", "Tetracapsuloides bryosalmonae", "Ceratomyxa shasta" leeches, nematode, Trematoda, Platyhelminthes and fish louse), viral disorders, metabolic disorders, inappropriate water conditions (insufficient aeration, pH, water hardness, temperature and ammonia poisoning) and malnutrition.

External bacterial infections may cause spots or streaks on the body which appear red or orange Dropsy (bloating) is also a sign of a bacterial infection. "False fungal infections" look like fungus but is actually a bacterial infection known as Columnaris. These symptoms may include a white or gray film on the body.

Sudden Death Syndrome (SDS) in Soybean plants quickly spread across the southern United States in the 1970s, eventually reaching most agricultural areas of the US. SDS is caused by a Fusarium fungi, more specifically the soil borne root pathogen "Fusarium virguliforme," formerly known as "Fusarium solani" f. sp. "glycines"."." Losses could exceed hundreds of millions of dollars in US soybean markets alone making it one of the most important diseases found in Soybeans across the US

Panama disease is a plant disease of the roots of banana plants. It is a type of Fusarium wilt, caused by the fungal pathogen "Fusarium oxysporum f. sp. cubense" (Foc). The pathogen is resistant to fungicide and cannot be controlled chemically.

During the 1950s, Panama disease wiped out most commercial Gros Michel banana production. The Gros Michel banana was the dominant cultivar of bananas, and the blight inflicted enormous costs and forced producers to switch to other, disease-resistant cultivars. New strains of Panama disease currently threaten the production of today's most popular cultivar, Cavendish.

Certain techniques can be used to determine which pathogen is causing disease. One standard technique for distinguishing strains is microscopy. Under a microscope, "M. pinodes" can be diagnosed by the presence of pseudothecia. "P pinodella" can be diagnosed by the size of conidia produced. "P. pinodella" produces conidia that are smaller than the conidia of "M. pinodes" or "A. pisi". "A. pisi" can be diagnosed by the color of the conidia. In comparison to the light colored, buff spore masses of "M. pinodes" and "P. pinodella" produced on oatmeal agar, "A. pisi" spores masses are carrot red.

Other techniques for diagnosis involve serological assays, isoenzyme analysis, restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNA (RAPD) assays, and by using monoclonal antibodies.

Most of the SDS symptoms can be confused with other factors like nutrient deficiencies and some other diseases like brown stem rot and stem canker. Usually the first symptom seen is interveinal chlorosis, which is the yellowing of the plant material between the leaf veins. When leaves begin to die, puckering and mottling can also be observed along with the chlorosis. As severity increases, necrosis (death of cells) occurs and eventually these leaves will fall off, leaving only petioles left on the stem. If the conditions are right (cool and wet), these symptoms can appear suddenly, causing large yield reductions. Normally, this is seen in mid or late July around the time of flowering and pod production.

In addition to foliar symptoms, the stem of the soybean plant can show symptoms as well. If a soybean stem with SDS is split, the pith will be visibly white while the cortical tissue around the pith will be tan to light brown in color. If the pith is brown in color (or if the whole stem looks brown on the inside), it is likely that the plant has brown stem rot, rather than SDS

Along with the above ground foliar and stem symptoms, the roots usually show some kind of rotting and decrease in vigor compared to other healthy soybean roots. If soil conditions are moist, roots are also likely to show blue masses of spores (macroconidia) around the taproot just below the soil surface. Blue fungal masses, found along with the foliar and stem symptoms, are strong diagnostic indicators for SDS

There are two different manifestations of rainscald: the winter form, which is more severe due to the longer coat of the horse, and the summer form, which is less severe. Horses are usually affected on the back, head, and neck, where insects commonly bite, and the legs, which are commonly infected if the horse is kept in moist footing. Initially, the horse will display a matted coat and bumps which will then progress to crusty scabs and lesions. The animal may also be itchy and display signs of discomfort.

Two external symptoms help characterize Panama disease of banana:

- Yellow leaf syndrome, the yellowing of the border of the leaves which eventually leads to bending of the petiole.

- Green leaf syndrome, which occurs in certain cultivars, marked by the persistence of the green color of the leaves followed by the bending of the petiole as in yellow leaf syndrome. Internally, the disease is characterized by vascular discoloration. This begins in the roots and rhizomes with a yellowing that proceeds to a red or brown color in the pseudostem.

These symptoms often get confused with the symptoms of bacterial wilt of banana, but there are ways to differentiate between the two diseases:

- Fusarium wilt proceeds from older to younger leaves, but bacterial wilt is the opposite.

- Fusarium wilt has no symptoms on the growing buds or suckers, no exudates visible within the plant, and no symptoms in the fruit. Bacterial wilt can be characterized by distorted or necrotic buds, bacterial ooze within the plant, and fruit rot and necrosis.

Once a banana plant is infected, it will continue to grow and any new leaves will be pale in color. Recovery is rare, but if it does occur any new emerging suckers will already be infected and can propagate disease if planted.

"Fusarium oxysporum f. sp. cubense" (Foc) is most prominent in banana and plantain, but some other similar relatives are also susceptible to infection. Different races of the disease are used to classify different major hosts affected by Foc. Race 1 was the initial outbreak which destroyed much of the world's Gros Michel bananas. Cavendish bananas are resistant to race 1, but tropical race 4 (or subtropical race 4) is the classification for Foc which affects Cavendish. Race 2 affects a cooking and dessert banana, Bluggoe.

Symptoms can be found on both beet roots and foliage, although foliar symptoms are not always present. If present, foliar symptoms include dark streaking along petioles and viscous froth deposits on the crown which are a by-product of bacterial metabolism. Petioles can also become necrotic and demonstrate vascular necrosis. When roots become severely affected, wilting also occurs. Below ground symptoms include both soft and dry root rot. Affected vascular bundles in roots become necrotic and brown, and tissue adjacent to necrosis becomes pink upon air contact. The plants that do not die completely may have rotted-out, cavernous roots.

Various pathogens can cause root rot in beets; however the black streaking on petioles and necrotic vascular bundles in roots and adjacent pink tissue help to distinguish this disease from others such as Fusarium Yellows. Additionally, sampling from the rhizosphere of infected plants and serological tests can confirm the presence of "Erwinia caratovora" subs.

Fish infected with typical BCWD have lesions on the skin and fins. Fins may appear dark, torn, split, ragged, frayed and may even be lost completely. Affected fish are often lethargic and stop feeding. Infection may spread systemically. Salmonid fish can also get a chronic form of BCWD following recovery from typical BCWD. It is characterised by erratic “corkscrew” swimming, blackened tails and spinal deformities.

In rainbow trout fry syndrome, acute disease with high mortality rates occurs. Infected fish may show signs of lethargy, inappetance and exopthalmos before death.

A presumptive diagnosis can be made based on the history, clinical signs, pattern of mortality and water temperature, especially if there is a history of the disease in the area. The organism can be cultured for definitive diagnosis. Alternatively, histology should show periostitis, osteitis, meningitis and ganglioneuritis.

Ornamental fish kept in aquariums are susceptible to numerous diseases. Due to their generally small size and the low cost of replacing diseased or dead fish, the cost of testing and treating diseases is often seen as more trouble than the value of the fish.

Due to the artificially limited volume of water and high concentration of fish in most aquarium tanks, communicable diseases often affect most or all fish in a tank. An improper nitrogen cycle, inappropriate aquarium plants and potentially harmful freshwater invertebrates can directly harm or add to the stresses on ornamental fish in a tank. Despite this, many diseases in captive fish can be avoided or prevented through proper water conditions and a well-adjusted ecosystem within the tank.

Physiological plant disorders are caused by non-pathological conditions such as poor light, adverse weather, water-logging, phytotoxic compounds or a lack of nutrients, and affect the functioning of the plant system. Physiological disorders are distinguished from plant diseases caused by pathogens, such as a virus or fungus. While the symptoms of physiological disorders may appear disease-like, they can usually be prevented by altering environmental conditions. However, once a plant shows symptoms of a physiological disorder it is likely that that season’s growth or yield will be reduced.

Rainscald (also known as "dermatophilosis", "rain rot" and "streptothricosis") is a common skin disease in horses that is caused by the bacterium "Dermatophilus congolensis". This is the same organism that causes Mud fever in horses. This disease is very common in cows, sheep and goats and is also found occasionally in cats, dogs, and humans. D. congolensis is a gram-positive bacterium that is thought to originate from the soil. It commonly causes disease in moist tropical areas, but can also be found in wet northern environments. Moisture and high temperatures facilitate the dispersal and penetration of zoospores into the skin, contributing to the spread of the disease.

Ticks, biting flies, and contact with other infected animals also causes the spread of rainscald. Once in the skin, the bacteria cause inflammation of the skin as well as the typical symptoms associated with rainscald.

Bacterial cold water disease (BCWD) is a bacterial disease of salmonid fish. It is caused by "Flavobacterium psychrophilum" (previously classified in the genus "Cytophaga"), a gram-negative rod-shaped bacterium of the family Flavobacteriaceae. The disease typically occurs at temperatures below 13⁰C, and it can be seen in any area with water temperatures consistently below 15⁰C. Salmon are the most commonly affected species. This disease is not zoonotic.

Asymptomatic carrier fish and contaminated water provide reservoirs for disease. Transmission is mainly horizontal, but vertical transmission can also occur.

BCWD may be referred to by a number of other names including cold water disease, peduncle disease, fit rot, tail rot and rainbow trout fry mortality syndrome.

Root rot is a condition found in both indoor and outdoor plants, although more common in indoor plants with poor drainage. As the name states, the roots of the plant rot. Usually, this is a result of overwatering. In houseplants, it is a very common problem, and is slightly less common in outdoor plants. In both indoor and outdoor plants, it is usually lethal and there is no effective treatment.

The excess water makes it very difficult for the roots to get the air that they need, causing them to decay. To avoid root rot, it is best to only water plants when the soil becomes dry, and to put the plant in a well-drained pot. Using a heavy soil, such as one dug up from outdoors can also cause root rot.

Many cases of root rot are caused by members of the water mould genus "Phytophthora"; perhaps the most aggressive is "P. cinnamomi". Spores from root rot causing agents do contaminate other plants, but the rot cannot take hold unless there is adequate moisture. Spores are not only , but are also carried by insects and other arthropods in the soil.

A plant with root rot will not normally survive, but can often be propagated so it will not be lost completely. Plants with root rot should be removed and destroyed.

Fin rot is a symptom of disease or the actual disease in fish. This is a disease which is most often observed in aquaria and aquaculture, but can also occur in natural populations.

Fin rot can be the result of a bacterial infection ("Pseudomonas fluorescens", which causes a ragged rotting of the fin), or as a fungal infection (which rots the fin more evenly and is more likely to produce a white 'edge'). Sometimes, both types of infection are seen together. Infection is commonly brought on by bad water conditions, injury, poor diet, stress, or as a secondary infection in a fish which is already stressed by other disease.

Fin rot starts at the edge of the fins, and destroys more and more tissue until it reaches the fin base. If it does reach the fin base, the fish will never be able to regenerate the lost tissue. At this point, the disease may begin to attack the fish's body; this is called Advanced Fin and Body rot.

Fin rot is common in bettas due to poor water conditions in pet stores.

The first sign of a foot-rot infection is when the skin between the claws of the hoof begins to swell (cellulitis). Swelling usually appears 24 hours after infection. The skin between the toes may be very red and tender and the toes may separate because of all the swelling. This is very painful to the animal and can cause lameness. The animal may also have a raised body temperature. A crack can develop along the infected part and is yellow in color. The foot will have a foul odor. Tendons and joints in the area can become infected, which is much harder to treat. A condition known as "super foot rot" is seen in some animals. Super foot rot infection occurs much faster and is usually much more severe. Most normal foot rot treatments will not cure this foot rot and a veterinarian should be contacted immediately.

Vaccines have been developed, but their efficacy is questionable and the immunity they provide is of short duration.