The disease is characterized by cutaneous and renal changes with the latter being ultimately fatal.

Common symptoms include, but are not limited to:

- Cutaneous lesions involving erythema, erosion, ulceration occurring mainly on extremities such as distal limbs, muzzle and ventrum

- Pyrexia (fever)

- Lethargy or malaise

- Anorexia

- Vomiting or retching

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.

Alabama rot or idiopathic cutaneous and renal glomerular vasculopathy (CRGV) is an often fatal condition in dogs. It was first identified in the USA in the 1980s in greyhounds. The initial symptoms are skin lesions on the legs, chest and abdomen followed by renal involvement.

In November 2012 the first cases were identified in the UK. In January 2014, the outbreak in England was identified as having the same or similar histological and clinical findings as Alabama rot, although a wide range of breeds were affected. The disease has continued to spread across England, with a case being reported as far north as North Yorkshire in March 2015. A UK map posted on-line shows confirmed (with post-mortem) and unconfirmed (without post-mortem) cases of Alabama rot since December 2012. In May 2017 it was reported that 98 deaths from the disease have occurred in the UK, including 15 in 2017.

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.

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.

The dry gangrene is a result of vasoconstriction induced by the ergotamine-ergocristine alkaloids of the fungus. It affects the more poorly vascularized distal structures, such as the fingers and toes. Symptoms include desquamation or peeling, weak peripheral pulses, loss of peripheral sensation, edema and ultimately the death and loss of affected tissues. Vasoconstriction is treated with vasodilators.

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.

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.

Convulsive symptoms include painful seizures and spasms, diarrhea, paresthesias, itching, mental effects including mania or psychosis, headaches, nausea and vomiting. Usually the gastrointestinal effects precede central nervous system effects.

Diagnosis is most commonly done with the identification of bacteria in the lesions by a microscope observation. Ticks, biting flies, and contact with other infected animals also causes the spread of rainscald. A scab will be taken from the affected animal and stained so that the bacteria are visible under a microscope inspection. A positive diagnosis of rainscald can be confirmed if filamentous bacteria are observed with as well as chains of small, spherical bacteria. If a diagnosis cannot be confirmed with a microscope, blood agar cultures can be grown to confirm the presence of "D. congolensis". The resulting colonies have filaments and are yellow in colour.

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.

Laurel wilt, also called laurel wilt disease, is a vascular disease caused by the fungus "Raffaelea lauricola", which is transmitted by the invasive redbay ambrosia beetle, "Xyleborus glabratus". The disease affects and kills members of the laurel family. The avocado is perhaps the most commercially valuable plant affected by laurel wilt.

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").

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

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.

Noble rot (; ; ; ) is the beneficial form of a grey fungus, "Botrytis cinerea", affecting wine grapes. Infestation by "Botrytis" requires moist conditions. If the weather stays wet, the damaging form, "grey rot," can destroy crops of grapes. Grapes typically become infected with "Botrytis" when they are ripe. If they are then exposed to drier conditions and become partially raisined this form of infection is known as noble rot. Grapes when picked at a certain point during infestation can produce particularly fine and concentrated sweet wine. Wines produced by this method are known as botrytized wines.

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.

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 the greenhouses, but can also occur in the field. The pathogen is likely to grow in humid and cool conditions. In the 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 (Cooke 1883), although it is original from South and Central America. The causal fungus of tomato leaf mold may also be referred as Cladosporium fulvum (Cooke 1883), a former name.

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.

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

The symptoms of Cherry X disease vary greatly depending on the host. On cherry hosts symptoms can usually first be seen on the fruits, causing them to be smaller in size with a leathery skin. Pale fruit is common at harvest time. It is common for symptoms to first be seen in a single branch. The branch may lose its older leaves, and the leaves tend to be smaller with a bronzed complexion.

The rootstock that the cherry is grafted onto can play a significant role in the disease symptoms seen. Rootstocks of Mahaleb cherry exhibit different symptoms from stocks of Colt, Mazzard, or Stockton Morello. When the scion is grafted onto Mahaleb, symptoms consistent with Phytophthora root rot can be seen. To distinguish between root rot and x-disease the wood under the bark at the graft union should be examined. If it is x-disease the wood at the union will have grooves and pits this causes a browning of the phloem and shows the cells in decline. This rapid decline is caused by the rootstock cells near the graft union dying in large quantities. Foliage begins to turn yellow and the curl upward and inward toward the leaf midrib. Trees infected with Mahaleb rootstock die by late summer or early the following year.

When Cherries are grafted onto Colt, Mazzard, or Stockton Morello rootstocks, there is a different range of symptoms. Affected leaves are smaller than normal and the foliage may be sparse. Dieback of shoot tips is common as the disease progresses. Fruit on branches are smaller, lighter, pointed, low sugar content, poor flavor, and a bitter taste.

Peaches are the next most common economic fruit host of the X-disease. Symptoms can be seen after about two months single branches will begin to show symptoms of their individual leaves. These leaves curl up and inward with irregular yellow to reddish-purple spots. These spots can drop out leaving “shotholes”. Leaves that are affected by the disease will fall prematurely. After 2–3 years the entire tree will show symptoms.

The disease affect most stone plants including peaches, apricots and plums. The symptoms can generally be found in three major parts of plant: fruits, twigs, and leaves. The symptoms on leaves and twigs are often considered as the least notable. Infected leaves initially show small and green colored lesions on under the leaves. They progress into yellowish brown and eventually appear as dark brown or black spots.

Twig lesions start to form on green young stems. The lesions are about 3 up to 6.5 mm in diameter size. They usually first have reddish brown colors then which will turn into darker colors as they enlarge to an oval shape of 3 x 6mm approximately.

About six weeks after petals are fallen, the first and most notable and serious symptoms appear on fruits. Spots, which generally range from 1 to 2 mm in diameter size, are formed on the end of stem. They gradually change its color into dark green or black and grow about few millimeters in diameter. As they enlarge, yellow circles will form around the velvety dark green spots. The spots have raised appearance on fruits instead of sunken figures which can be found most prevalently in other fungal infections. In some severe cases, fruits may be stunted or opened and exposed to further infection by airborne microorganisms.

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.

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.

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.