Plant Disease Library

A parasitic algal disease producing rust-colored, velvety circular spots.

A fungal rust specific to Aloe and related succulents, producing raised orange-brown pustules.

A fungal leaf disease causing necrotic blotches and early defoliation on susceptible cultivars.

A fungal disease of susceptible tangerine hybrids causing necrotic spots on young leaves, twigs, and fruit.

A fungal disease causing concentric-ringed brown leaf spots starting on older leaves.

A common, usually minor fungal leaf spot on stressed or damaged houseplant foliage.

A fungal fruit rot that can develop internally with few external symptoms until the fruit is cut.

A fungal disease causing dark, dry rot on berries, often at cracks or wounds.

A bacterial disease producing angular, vein-bounded leaf spots that later tear out, giving a "shot-hole" look.

A fungal disease causing leaf lesions and a stalk rot that can lead to plant lodging and top dieback.

A fungal disease of ripening chili fruit producing sunken, concentrically ringed spots with colorful spore masses.

A fungal disease causing twig dieback and wound-related fruit rot, often following stress or injury.

A fungal disease causing dark, sunken spots on leaves, stems, and fruit with pink spore masses in humid weather.

A fungal disease producing distinctive "bird's-eye" spots on leaves, shoots, and berries.

A fungal disease causing sunken, water-soaked spots on leaves and fruit rot in humid weather.

A common fungal disease causing sunken, dark leaf spots on many broad-leaved houseplants.

A fungal disease of ripening pepper fruit producing sunken, concentrically ringed spots.

A fungal disease causing fruit rot and crown rot, most damaging in warm, wet climates.

A fungal disease of ripening tomato fruit producing small sunken spots with concentric rings.

A common sap-sucking pest that clusters on new growth and flower buds.

A graft-transmitted virus causing cream-to-yellow mosaic patterning and reduced vigor.

A fungal disease covering new shoots and leaves in white powdery growth, russeting fruit skin.

One of the most important apple diseases, producing olive-to-black velvety spots on leaves and corky scab lesions on fruit.

A usually latent virus in apple that can decline sensitive rootstock/scion combinations.

A latent virus on most apple cultivars that reduces vigor mainly on sensitive rootstocks.

A direct sun-exposure injury on fruit that has lost protective canopy cover.

A nematode-vectored virus problem causing gradual decline and breakage at the graft union.

A soilborne fungal disease causing gradual vine decline, often on sites with a history of woody vegetation.

A bacterial disease causing shoot necrosis and cane cankers.

A serious seed- and transplant-borne bacterial disease causing wilting, stem cankers, and "bird's-eye" fruit spots.

A bacterial disease spread by contaminated transplants and wet-weather handling, producing translucent angular leaf spots visible against light.

A warm-weather bacterial disease causing scabby leaf and fruit spots that can defoliate plants.

A bacterial disease specific to ivy, producing dark water-soaked leaf and stem spots.

A common bacterial leaf spot affecting many foliage houseplants in humid conditions.

A bacterial disease of aroid houseplants causing water-soaked leaf spots that can lead to a rapid leaf collapse.

A seed-borne bacterial disease that follows the vascular ring, producing a cheesy yellow rot.

A wet-weather bacterial disease causing mushy tuber rot and blackened stem bases.

An aggressive bacterial disease that turns stems and rhizomes into a foul-smelling mush.

A cool-weather bacterial disease causing small dark specks on leaves and fruit.

A warm-weather bacterial disease causing scabby leaf and fruit spots that can defoliate plants.

A warm-weather bacterial disease causing scabby leaf and fruit spots that can defoliate plants.

A destructive vascular wilt spreading through infected seed rhizomes and contaminated soil/tools.

A soilborne vascular wilt causing rapid collapse and a browning ring inside the tuber.

A destructive vascular wilt spread through insect-visited flowers, contaminated tools, and planting material.

An aphid-transmitted virus causing mosaic streaking on pseudostems, leaves, and bracts.

A generally mild virus associated with mealybug-vectored spread.

A mealybug-transmitted virus (sometimes latent in the plant genome) causing necrotic vein streaking.

A fungal disease producing dark concentric bands on leaf sheaths in humid weather.

A fungal disease starting at the bulb's basal plate and spreading upward through the bulb.

A calcium-deficiency disorder causing small sunken pits in fruit flesh.

A fungal disease producing tiny black fruiting structures ("black dot") visible in tuber skin.

A destructive fungal disease that shrivels berries into hard black "mummies".

A bacterial disease producing raised dark blisters on fruit skin, mainly on susceptible cultivars.

A calcium-related fruit disorder made worse by irregular watering, not a pathogen disease.

A calcium-related fruit disorder made worse by irregular watering, not a pathogen disease.

An uneven-ripening disorder linked to potassium deficiency and heat or light stress.

A fast-spreading postharvest storage rot entering through wounds.

A fungal disease affecting palm foliage, including houseplant palms, causing leaf blight and dieback.

A latent fungal disease that produces dark, sunken fruit lesions that appear as fruit ripens.

A humidity-driven fungus that coats dying or damaged plant tissue in gray, fuzzy mold.

A fungal disease causing brown rot in the orchard or gray mold in storage, often from wounds or the calyx.

A rapid-growth disorder causing internal discoloration or a cavity at the tuber center.

A controlled-atmosphere storage injury caused by excess carbon dioxide or insufficient oxygen.

A destructive root nematode that causes mature plants to topple over in wind ("blowdown").

A fungal disease producing dark, sunken cankers on fruit and stems.

A blossom-end deformity caused by cool temperatures disrupting fruit set.

A fungal leaf spot causing a distinctive "frogeye" pattern and defoliation.

A fungal leaf spot causing circular tan lesions and defoliation.

A fungal leaf spot producing small, gray-centered spots with dark margins.

A fungal leaf spot genus affecting a wide range of ornamental foliage plants.

A fungal leaf spot causing a distinctive "frogeye" pattern and defoliation.

A heat- and drought-favored fungal disease producing microsclerotia-studded lesions and vine wilting.

An emerging heat- and drought-favored crown disease, often turning up where soil fumigation was incomplete.

A cold-storage/transport disorder that impairs normal ripening.

A humid-weather fungal disease starting a soft, whiskered rot at the flower end.

A cold-stress disorder preventing the flower bunch from emerging properly.

A fungal disease starting at the flower end of the finger, resembling a burned cigar tip.

A fungal disease of quarantine significance that blemishes fruit rind with hard, gray-centered spots.

A rain-splash disease affecting low-hanging fruit, producing a pungent brown, leathery rot.

A regulated bacterial disease causing raised corky lesions on leaves, stems, and fruit, spread by wind-driven rain.

A devastating, incurable bacterial disease spread by the Asian citrus psyllid, causing tree decline and misshapen fruit.

A fungal disease producing raised, sandpaper-like spots from spores released by dead wood.

A sharpshooter-transmitted bacterial disease causing variegated leaf chlorosis and hardened, small fruit.

An extremely stable, mechanically transmitted virus causing mottled, malformed foliage.

A widespread fungal disease producing small golden-brown pustules on both leaf surfaces.

An actinomycete disease of dry, alkaline soils producing rough, corky scab lesions on tuber skin.

A fungal disease producing large, distinctive galls filled with black spore masses.

A bacterial disease producing tumor-like galls at the crown and graft union, often following winter injury.

An aphid-transmitted virus that can cause severe "heart rot" and bunch distortion in banana.

An aphid-transmitted virus causing mosaic mottling, stunting, and misshapen fruit.

A group of aphid-transmitted viruses causing mosaic mottling and stunting in pepper.

A group of aphid-transmitted viruses causing mosaic mottling and leaf distortion in tomato.

A microscopic mite too small to see with the naked eye, causing distorted new growth in African Violet and similar plants.

A well-documented, specific cause of root and crown rot in Peace Lily, spreading in overwatered, warm greenhouse-style conditions.

One of the two most common and damaging orchid viruses worldwide, spread mechanically through infected sap.

A widespread, migratory root-feeding nematode that stunts growth and can vector certain plant viruses.

A nursery disease complex that collapses seedling stems at the soil line.

An aggressive bacterial disease causing rapid blackleg and tuber soft rot, more virulent than related Pectobacterium species.

A wet-soil oomycete disease that distorts the tassel into a leafy mass known as "crazy top".

A fast-spreading, humidity-driven disease producing purple-gray fungal down on leaf undersides.

A humidity-driven oomycete disease producing grayish-purple fungal down on leaves.

A rain-driven oomycete disease producing yellow "oil spot" lesions and white downy growth on leaf undersides.

A common fungal disease producing dark, concentric "target spot" lesions on foliage and tubers.

A common fungal disease producing dark, concentric "target spot" lesions starting on older leaves.

A slow-developing fungal disease entering through pruning wounds and gradually killing cordons and arms.

A minor fungal disease producing small, eye-shaped leaf lesions.

A minor fungal leaf disease producing small tan spots ringed with a dark border and yellow halo.

A fast-moving, warm-weather bacterial disease that blackens blossoms and shoots and can girdle limbs with cankers.

A nematode that moves in water films on foliage rather than through soil, damaging leaves directly.

Radial or concentric cracks caused by irregular water uptake during fruit development.

The dark, ringed spots on the leaves are consistent with a fungal or bacterial leaf spot, often spread by water sitting on foliage.

A wet-soil disease causing yellowing leaves and a soft, watery rhizome rot.

A common nuisance pest whose larvae live in moist potting soil and can damage roots of seedlings and weak plants.

A soilborne fungal disease that rots the crown and roots, causing wilting and internal stem discoloration.

A common storage disease entering tubers through wounds, producing a sunken, wrinkled dry rot.

A progressive fungal disease causing yellowing from the lower leaves upward and dry rhizome rot.

A soilborne fungal disease causing yellowing foliage and basal bulb rot.

A fungal disease causing stem lesions and fruit rot in pepper.

A soilborne fungus causing wilting and root/crown rot, often introduced on contaminated potting mix or infected divisions.

A soilborne wilt causing one-sided yellowing, vascular browning, and plant collapse.

A persistent soilborne wilt causing one-sided yellowing and vascular browning.

A soilborne wilt/rhizome rot complex that yellows pseudostems and rots the underground rhizome.

Causes leaf blotch and a stem-end fruit rot, spread from infected crop residue left in the field.

A mealybug-transmitted virus complex that delays ripening and discolors leaves between the veins.

A dagger-nematode-transmitted virus causing fan-shaped leaf malformation and reduced yield.

An economically important fungal disease producing rectangular, vein-bounded lesions that can cause severe defoliation.

A humidity-driven fungal disease that engulfs grape clusters in gray mold, especially after rain near harvest.

The most damaging strawberry fruit disease worldwide, causing gray, fuzzy fruit rot, especially in cool, wet seasons — losses can exceed 50%.

A humidity-driven fungal mold affecting stems, leaves, and fruit, often starting at wounds or dead flower tissue.

A fungal leaf disease causing greasy-looking blister spots and premature leaf drop.

A common and fast-spreading postharvest storage rot.

A tuber-bulking disorder caused by irregular soil moisture.

A bacterial disease producing yellow streaking and gummy ooze from cut stalks.

A fungal disease causing amber gum-oozing stem lesions and vine collapse.

A fungal disease producing pale, water-soaked leaf spots that can coalesce.

The historically devastating disease behind the Irish potato famine, destroying foliage and tubers under cool, wet conditions.

An explosive, cool-weather disease capable of destroying a crop within days under favorable conditions.

Produces small purple leaf spots that enlarge into scorched-looking dead patches, also affecting petioles, flowers, and fruit caps.

One of the most widespread strawberry diseases, causing purple-bordered leaf spots and cosmetic "black seed" spotting on fruit.

A soilborne disease causing tough, bitter, inedible fruit, worst in poorly drained soil after heavy rain.

A migratory nematode that tunnels through root tissue, causing lesions and weakening the plant.

Leggy growth and pale, smaller new leaves suggest the plant isn't getting enough light for its current spot.

An aphid-transmitted virus causing mosaic mottling, stunting, and reddening in some hybrids.

A common sap-sucking pest that hides in leaf joints and produces a cottony white wax coating.

A pollination-related disorder causing deformed pepper fruit.

Older, lower leaves turning uniformly pale yellow while new growth stays green is a textbook nutrient deficiency.

A fungal disease producing long, cigar-shaped lesions capable of reducing yield significantly.

A common, highly stable orchid virus often found alongside Cymbidium mosaic virus in mixed infections.

A fungal disease causing water-soaked lesions and tip dieback on onion leaves.

A major storage disease causing soft, moldy rot at the neck of cured bulbs.

A seed- and soil-borne fungal disease that kills onion seedlings.

A persistent soilborne disease that can remain viable in soil for many years.

Parasitic flowering plants (such as mistletoe or dodder) that attach to branches and reduce vigor.

A seed-borne, highly stable virus causing mild mosaic mottling and occasional fruit distortion.

An aphid-transmitted virus causing mottling and stunted growth in chili.

A fungal disease causing pale-centered leaf spots and bleached, cracked canes.

Causes V-shaped, purple-bordered leaf lesions and a soft pink stem-end fruit rot, more common after wet autumns.

A fungal leaf spot producing tan-centered spots with dark margins.

A stress response in which lower leaves curl upward, often confused with a viral or nutrient disease.

An aggressive soilborne disease causing damping-off, root/crown rot, and fruit rot in waterlogged soil.

An aggressive soilborne disease causing damping-off, root/crown rot, and fruit rot in waterlogged soil.

A soilborne oomycete disease causing sudden plant collapse, distinct from the related red stele root rot.

A soilborne disease causing gummy trunk cankers, root decay, and canopy decline.

A soilborne oomycete disease causing water-soaked fruit rot, worst on fruit near the ground.

One of the most common causes of houseplant death, rotting roots in overwatered or poorly drained pots.

A specific, documented cause of root rot in Pothos, distinct from the more general Phytophthora cinnamomi.

A sharpshooter-transmitted bacterial disease causing rapid vine decline and death.

A tuber disorder causing pink discoloration and slight rot around the eyes.

A warm-soil fungal disease that turns roots pink before they shrivel and die.

A wet-soil disease named for the pink color tubers develop when cut and exposed to air.

A fungal disease of citrus blossoms that causes flowers to drop prematurely and reduces fruit set.

A nutrient deficiency causing marginal leaf scorch and reduced bunch size.

A nematode-transmitted virus causing ringspot patterns on leaves and tubers.

A light-exposure disorder that turns tuber flesh green and raises solanine levels.

An aphid-transmitted virus causing upward leaf rolling and internal tuber discoloration.

An aphid-transmitted virus causing mosaic mottling, leaf drop-streak, and stunting.

A fungal disease that coats African Violet leaves and flowers in white powdery growth, especially in cool, still air.

A fungal disease producing yellow leaf blotches with white powdery growth underneath, causing premature leaf drop.

A common fungal disease that coats leaves and stems in white powdery growth, reducing yield.

One of the most important grape diseases, coating leaves, shoots, and berries in powdery fungal growth.

A fungal disease producing yellow leaf blotches with white powdery growth underneath.

Covers leaves, flowers, and fruit in white powdery fungal growth and curls leaf edges upward.

A fungal disease producing yellow leaf blotches with white powdery growth underneath.

A pollination-related disorder producing lightweight, hollow fruit.

A fungal disease producing purple-brown, concentrically ringed leaf lesions.

A wet-soil disease causing seedling damping-off and fruit/root rot.

A fast-moving water mold that rots roots in soggy, poorly aerated potting mix.

One of the most destructive sugarcane diseases, producing red internal stalk discoloration with white cross-bands.

A serious root-rot disease of cool, wet, poorly drained soil that stunts and kills plants, with a diagnostic reddish core inside the root.

A bacterial disease producing narrow red leaf stripes that can progress to a top rot.

A common soilborne fungus causing stem cankers below ground and black "scurf" on tuber skin.

A soilborne fungus causing root and stem rot, especially in dense, moist potting mix.

A complex root-rot problem causing stunted, low-vigor plants with blackened, sparse root systems.

A postharvest/storage rot that turns berries brown, limp, and leaky, quickly covered in white fungal growth.

Root-feeding nematodes causing galls or lesions, tuber blemishes, and stunted growth.

A root-galling nematode that stunts plants and reduces bunch weight.

A widespread nematode that galls roots and stunts cucurbit plants.

A widespread nematode that galls roots and stunts pepper plants.

A root-galling nematode that stunts growth and reduces tillering.

A widespread nematode that galls roots and stunts plants, especially in warm sandy soils.

The soil is likely staying wet too long between waterings, suffocating the roots and letting fungus take hold.

A graft-transmissible virus complex causing pitted, grooved wood beneath the bark.

A fungal disease that turns fruit spots gummy and corky, and tears out leaf lesions into a "shot-hole" look.

A storage disorder causing diffuse skin browning from volatile compound buildup.

A fungal stem rot producing cottony white mold and hard black sclerotia.

A common fungal leaf spot that starts on lower leaves and can cause severe defoliation if untreated.

A cosmetic storage disease that gives tuber skin a silvery sheen.

A widespread fungal disease producing a long, curved black whip-like structure from the growing point.

A sap-sucking pest that attaches to stems and leaves under a waxy, shell-like covering, making it easy to miss.

A fast-spreading postharvest rot affecting ripe or wounded fruit.

A cosmetic fungal complex that smudges or speckles fruit skin without affecting flesh quality.

A cosmetic fungal disease that blotches the fruit rind without significantly harming the tree.

A cosmetic fungal disease that grows on insect honeydew, coating leaves in black soot-like mold.

A hot, humid-weather fungus that girdles stems at the soil line with white, thread-like growth.

A hot-weather soil fungus that girdles the stem at the soil line, causing sudden wilt.

A hot-weather soil fungus that girdles the stem at the soil line, causing sudden wilt.

A fungal disease producing tan, elongated lesions, historically severe on T-cytoplasm hybrids.

Fine speckling and faint webbing on the leaves point to spider mites, which thrive in dry indoor air.

The most common houseplant pest in dry indoor air, feeding on the underside of leaves and causing fine stippling.

A flea-beetle-vectored bacterial disease causing wilting and streaking, most damaging in sweet corn.

A highly damaging sandy-soil nematode that stunts roots and reduces stands.

An aphid-transmitted virus causing leaf crinkling and distortion in susceptible strawberry.

Usually symptomless alone, but worsens the symptoms of other strawberry viruses it combines with.

A virus complex causing yellow leaf margins, stunting, and vein netting, most damaging combined with other strawberry viruses.

An aphid-transmitted virus that can reduce yield up to 30% alone and up to 80% in mixed infections.

A pollen/seed/thrips-transmitted virus, symptomless on commercial cultivars but capable of reducing yield and runner production.

An aphid-transmitted virus causing chlorotic vein banding, most visible combined with strawberry latent C virus.

Root-feeding nematodes causing stunted, stubby roots; stubby-root nematode can also spread tobacco rattle virus.

A fungal disease starting a dark, sunken rot at the blossom (stylar) end of the fruit.

A leafhopper-transmitted phytoplasma disease causing excessive, stunted, grass-like tillering.

A sun-exposure injury on fruit that has lost its protective leaf cover.

A sun-exposure injury on fruit that has lost its protective leaf cover.

A fungal disease causing raised, warty scabs on fruit rind and leaves.

A fungal leaf spot producing distinctive target-like rings on foliage.

An extremely stable, mechanically transmitted virus causing mottled, malformed foliage.

A thrips-transmitted virus causing bronzing, ring spots, and one-sided fruit ripening.

A thrips-transmitted virus causing necrotic ring spots, bronzing, and fruit distortion.

The leaves are curling and crisping at the edges, a classic sign the plant isn't getting enough water between waterings.

A soilborne wilt causing yellowing, wilting, and internal vascular browning.

A soilborne wilt causing yellowing, wilting, and internal vascular browning.

A soilborne wilt that persists for years in soil and is especially damaging after tomato, potato, or pepper preceded strawberries.

A soilborne wilt causing V-shaped leaf yellowing and internal vascular streaking.

A sugar-alcohol accumulation disorder causing glassy, translucent flesh, often linked to late harvest.

A fungal wilt causing yellowing and internal stalk discoloration without the white cross-bands of red rot.

An aphid-transmitted virus causing midrib yellowing and reduced stalk growth.