Common Pests and Diseases
Spider mites (Two-spotted spider mite)
Spider mite infestation on bean foliage
Underside of a bean leaf showing spider mites.
Tropical spider mites necrosis to bean leaves on the field.
Spider mite symptoms on upper surface of leaves
Spider mite infestation on lower surface of leaf
Stippling injuries to leaves due to spider mites
Leaves stippled with yellow; leaves may appear bronzed; webbing covering leaves; mites may be visible as tiny moving dots on the webs or underside of leaves, best viewed using a hand lens; usually not spotted until there are visible symptoms on the plant; leaves turn yellow and may drop from plant.
In the home garden, spraying plants with a strong jet of water can help reduce buildup of spider mite populations; if mites become problematic apply insecticidal soap to plants; certain chemical insecticides may actually increase mite populations by killing off natural enemies and promoting mite reproduction.
Bacterial brown spot
Symptoms of bacterial brown spot (Pseudomonas syringae pv. syringae) on foliage of dry beans.
Symptoms of bacterial brown spot
Infected bean pods
Cupping of young leaflets of dry beans, a symptom of bacterial brown spot disease
"Water soaking" and necrosis on bean leaves, due to infection with bacterial brown spot disease
bacterial brown spot on dry bean, canopy shot - hole damage, early necrosis, disease, Pseudomonas syringae pv. syringae
Bacterial brown spot disease symptoms
Lesions of bacterial brown spot on a bean pod.
Early shot-hole lesions on leaves of dry beans due to bacterial brown spot
Bacterial brown spot on dry bean- branch lesions.
Small, dark brown necrotic spots on leaves which may be surrounded by a zone of yellow tissue; water soaked spots on pods which turn brown and necrotic; pods may twist and distort in area of infection.
Plant only certified seed; rotate crops regularly; remove crop debris from field after harvest.
syn. Xanthomonas axonopodis
Symptoms of bacterial blight on bean leaves
Leaf lesions caused by bean bacterial blight
Common bacterial blight water soaking lesions on dry bean pods, disease
Symptoms on both upper and lower surface of leaves
Symptoms on bacterial blight on pods
Lesions of common bacterial blight
Common bacterial blight water soaking on dry bean leaf, canopy symptoms
Symptoms on lower surface of leaf
Symptoms of bacterial blight on bean foliage
Bacterial blight of beans
Symptoms of common bacterial blight
common bacterial blight water soaking on dry bean leaf
Water-soaked spots on leaves which enlarge and become necrotic; spots may be surrounded by a zone of yellow discoloration; lesions coalesce and give plant a burned appearance; leaves that die remain attached to plant; circular, sunken, red-brown lesion may be present on pods; pod lesions may ooze during humid conditions.
Plant only certified seed; plant resistant varieties; treat seeds with an appropriate antibiotic prior to planting to kill off bacteria; spray plants with an appropriate protective copper based fungicide before appearance of symptoms.
Pseudomonas savastanoi pv. phaseolicola
Symptoms of halo blight on bean pods
Halo blight chlorosis
halo blight symptoms on upper surface of common bean leaflet, note circular yellow spots
Halo blight "water soaking" on a young bean pod
Halo blight chlorosis on bean leaves
Chlorosis and isolated lesions of halo blight on dry beans.
Halo blight symptom
Halo blight "water soaking" on a mature bean pod
halo blight symptoms on lower surface of common bean leaflet, note small water-soaked spots
Halo blight "water soaking" on a mature pod of red kidney beans
Small water-soaked spots on underside of leaves which turn necrotic and become visible on upper surface; lesions may develop an area of chlorotic tissue around the spots; lesions on expanding leaves may cause distorted leaves; red-brown lesions may be visible on pods; pod lesions may ooze or may turn tan in color.
Plant disease free seed or treat seed with an antibiotic to reduce levels of bacterium; rotate crops to non-hosts every 2 years; plow bean debris deeply in soil after harvest.
Alternaria leaf spot
Symptoms of Alternaria leaf spot on bean leaves and pods
Small irregular brown lesions on leaves which expand and turn gray-brown or dark brown with concentric zones; older areas of lesions may dry out and drop from leaves causing shot hole; lesions coalesce to form large necrotic patches
Plant beans in fertile soil; foliar fungicide application may be required
Colletotrichum lindemuthianum (Glomerella lindemuthiana)
Anthracnose symptoms on bean pods
Anthracnose symptoms on bean pods
Close-up view of a bean leaf petiole, displaying symptoms of bean anthracnose
leaf showing symptoms of beans anthracnose
Anthracnose symptoms on bean pod
Close-up of anthracnose lesion on bean pod
Close-up view of a bean pod, displaying symptoms of bean anthracnose
Symptoms of bean anthracnose
Anthracnose symptoms on beans and pods
Bean plants showing canopy symptoms
Small, dark brown to black lesions on cotyledons; oval or eye-shaped lesions on stems which turn sunken and brown with purple to red margins; stems may break if cankers weaken stem; pods drying and shrinking above areas of visible symptoms; reddish brown spots on pods which become circular and sunken with rust colored margin.
Plant resistant varieties; use certified disease free seed; avoid sprinkler irrigation, water plants at base; plow bean crop debris into soil.
Black root rot
Elongated red-purple lesions due black root rot on melon seedling
black root rot (Thielaviopsis basicola) symptom
Symptoms of black root rot (Thielaviopsis basicola)
Elongated red-purple lesions on root tissue which turns dark gray to black; lesions coalesce to form large dark areas on roots and stems; deep lesions can cause stunted growth, wilting leaves, defoliation and plant death.
Rotate crops with non-susceptible grasses; avoid excess irrigation or drought stress.
Fusarium root rot
Bean plant showing symptoms of fusarium wilt
Roots of drybeans showing advanced symptoms of Fusarium root rot caused by Fusarium oxysporum f.sp. phaseoli.
Young plants stunted with chlorotic leaves; older plants with chlorotic leaves and some leaf drop; severely decayed roots which are hollow and dry.
Practice long term crop rotation; avoid over or under watering plants; some bean varieties exhibit some tolerance.
White mold (Sclerotinia timber rot)
Bean pod and flower colonized by white mold
White mold symptoms on bean plants caused by Sclerotinia sclerotiorum
Symptoms in advance stage
Mycelium and sclerotia of white mold
White mold on bean stem and branches
Advanced symptoms of white mold (Sclerotinia sclerotiorum) on the branches and pods of a bean plant.
Field infested with white mold
Fallen blossoms of dry bean that have been colonized by white mold
Apothecia of white mold (Sclerotinia sclerotiorum) and fallen leaves of dry bean that have been colonized by white mold.
Advanced symptoms of white mold
Wilting and death of the bean canopy, an advanced symptom of infection with white mold
Wilting of a dry bean plant in the field, an initial symptom of infection with white mold
Flowers covered in white, cottony fungal growth; small, circular, dark green, water-soaked lesions on pods leaves and branches which enlarge and become slimy; cottony white growth may be visible on lesions during periods of high humidity; death of branches and/or entire plant.
There is no true immunity to white mold in any bean varieties; rotate crops with non-hosts like cereals and corn; plant rows parallel to direction of prevailing winds to prevent spread of disease from secondary hosts nearby; avoid excessive nitrogen fertilizer; use a wide row spacing.
Rhizoctonia damping-off, blight and rot (Rhizoctonia solani) symptoms
elongated sunken reddish-brown lesions on roots and stems at or below the soil line
Roots of drybeans showing advanced symptoms of Rhizoctonia root rot caused by Rhizoctonia solani.
Drybean seedlings showing symptoms of Pythium damping off caused by Pythium spp.
Fusarium damping-off (Fusarium solani) symptoms
Roots of drybean seedlings showing early symptoms of Rhizoctonia root rot caused by Rhizoctonia solani.
Death of seedling due to damping off
Damping Off on Snap Bean (Pythium and Rhizoctonia) Collapse of the lower stem area.
Drybean plants showing symptoms of Rhizoctonia and Pythium root rots caused by Rhizoctonia solani and Pythium spp. respectively in the field.
The pathogens attack any stage of crop beginning from seed rot; damping off of seedlings; or stunting, yellowing and death of older plants. Visible symptoms are the appearance of elongated sunken reddish-brown lesions on roots and stems at or below the soil line. Further the lesions girdle the stem, causing the death of the plant. Older plants may show little indication of the disease, although yields may be reduced. The pith may turn brick- red if invaded by the fungus.
Follow crop rotation with non host crops. Sow the seeds in warm soil with well prepared seed bed and proper depth. Treat seeds with a suitable fungicide.
Field of dry beans displaying prominent symptoms of bean rust
Defoliation of bean leaves due to rust disease
small yellow or white spots due to rust disease
Teliospores formed on infected leaves
Symptoms on beans stem
Telia of bean rust (Uromyces appendiculatus) on a bean leaf.
Rust disease infected plants
Initial symptoms of rust disease
Rust pustules on bean leaf
Close-up view of the pycnium of bean rust
Bean leaves showing "green island effect" due bean rust disease
Rust symptoms on bean pod
Telia of bean rust
Aecia of bean rust (Uromyces appendiculatus) on the stem
Initially the symptoms appear as small yellow/white spots on leaves. Later the spots become enlarged and shows raised brick red rust pustules (uredinia). Normally this pustules are surrounded by a yellow halo. Premature leaf drop may occur if the disease is severe.
Grow available resistant varieties. Remove and destroy the infected crop debris. Follow crop rotation. Keep the field free from weeds. If the disease is severe, spray suitable fungicide.
Aphids (Cowpea aphid, Pea aphid, etc.)
The aphids are tended by ants
Close-up of Black Bean Aphids (Aphis fabae) colony
Aphid infestation on bean plant
Ladybird beetle feeding on bean black aphids
Aphids on lower surface of leaves
Winged aphids, the vectors of Bean Common Mosaic Virus (BCMV), on a bean leaflet.
Black Bean Aphid Aphis fabae
Cowpea aphid (Aphis craccivora) infestation
Small soft bodied insects on underside of leaves and/or stems of plant; usually green or yellow in color, but may be pink, brown, red or black depending on species and host plant; if aphid infestation is heavy it may cause leaves to yellow and/or distorted, necrotic spots on leaves and/or stunted shoots; aphids secrete a sticky, sugary substance called honeydew which encourages the growth of sooty mold on the plants.
If aphid population is limited to just a few leaves or shoots then the infestation can be pruned out to provide control; check transplants for aphids before planting; use tolerant varieties if available; reflective mulches such as silver colored plastic can deter aphids from feeding on plants; sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use.
Armyworms (Beet armyworm, Western striped armyworm)
Beet armyworm (Spodoptera exigua) on leaf
Beet army worm late instar larvae
Larvae of beet armyworm
Beet armyworm eggs
Beet armyworm egg mass hatching
Beet armyworm (Spodoptera exigua) egg mass covered with hairs.
Damage due to early stage beet army worm larvae
Beet armyworm adult
Adult of beet armyworm
Singular, or closely grouped circular to irregularly shaped holes in foliage; heavy feeding by young larvae leads to skeletonized leaves; shallow, dry wounds on fruit; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside.
Organic methods of controlling armyworms include biological control by natural enemies which parasitize the larvae and the application of Bacillus thuringiensis; there are chemicals available for commercial control but many that are available for the home garden do not provide adequate control of the larvae.
Corn earworm on bean
Corn earworm (Helicoverpa zea) adults
Larvae feeding on leaf
Adult and larvae
Larvae damage leaves, buds, flowers, pods and beans; young caterpillars are cream-white in color with a black head and black hairs; older larvae may be yellow-green to almost black in color with fine white lines along their body and black spots at the base of hairs; eggs are laid singly on both upper and lower leaf surfaces and are initially creamy white but develop a brown-red ring after 24 hours and darken prior to hatching.
Monitor plants for eggs and young larvae and also natural enemies that could be damaged by chemicals; Bacillus thuringiensis or Entrust SC may be applied to control insects on organically grown plants; appropriate chemical treatment may be required for control in commercial plantations.
Loopers (Cabbage looper, Alfalfa looper)
Looper on bean leaf
soybean looper (Thysanoplusia orichalcea) on dry beans
Large or small holes in leaves; damage often extensive; caterpillars are pale green with a white lines running down either side of their body; caterpillars are easily distinguished by the way they arch their body when moving; eggs are laid singly, usually on the lower leaf surface close to the leaf margin, and are white or pale green in color.
Looper populations are usually held in check by natural enemies; if they do become problematic larvae can be hand-picked from the plants; an organically acceptable control method is the application of Bacillus thuringiensis which effectively kills younger larvae; chemical sprays may damage populations of natural enemies and should and should be selected carefully.
Stinkbugs (Consperse stinkbug, etc.)
Southern stinkbug feeding on bean leaf
Florida Preatory Stink Bug, Euthyrhynchus floridanus (beneficial insect)
Predaceous anchor stink bug (Stiretrus anchorago) attacking green stinkbug nymph.
Stinkbug feeding on bean pod
brown stink bug (Euschistus servus) eggs
Stinkbugs infestation on bean leaves
Globular stinkbug on leaf
Dark colored pinpricks on fruit surrounded by a lighter area that turns yellow or remains light green; stink bugs often carry pathogens in their mouthparts which can cause secondary infections and decay of fruit; adult insect is shield-shaped and brown or green in color; may have pink, red or yellow markings; eggs are drum shaped and laid in clusters on the leaves; larvae resemble the adults but are smaller.
Remove weeds around crop which may act as overwintering sites for stink bugs and practice good weed management throughout the year; organically accepted control methods include the use of insecticidal soaps, kaolin clay and preservation of natural enemies; chemical treatments are not recommended for tomatoes that are to be processed for paste or canning unless secondary infections with other pathogens are a concern.
Mexican bean beetle
Mexican bean beetle damage to bean foliage
Mexican bean beetle larva
Bean plant infested with Mexican bean beetle larvae
Adult Mexican bean beetle
Eggs laid on underside of bean leaf
Adult beetle and damage to bean foliage
Irregular patches of feeding damage on underside of leaves which causes the top surface of the leaf to dry out, giving the leaves a lacy appearance; insect will also damage flowers and small pods; pods may be damaged so badly that they drop from the plant; adult insect is an orange-brown beetle with black spots; larvae are fat-bodied grubs which taper at the end and are in rows of conspicuous spines
Some bean varieties may be less attractive hosts for the beetle, e.g. snapbeans are preferred hosts over lima beans; early varieties may escape damage form beetles beetle populations can be reduced by remove overwintering sites such as brush and leaves on the ground; handpick larvae and adults; brush eggs from leaves and destroy; apply insecticidal soap to leaf undersides if infestation is heavy
Cutworm larva severing plant stem
Cutworm damage to bean seedling
French beans attacked by Helicoverpa armigera. Note the larvae within the bean.
Cutworms will curl up into a characteristic C shape when disturbed
Eggs of western bean cutworm (Striacosta albicosta)
Cutworm feeding on plant stem
Bean leaf skeletonizer (Autoplusia egena) larva
Stems of young transplants or seedlings may be severed at soil line; if infection occurs later, irregular holes are eaten into the surface of fruits; larvae causing the damage are usually active at night and hide during the day in the soil at the base of the plants or in plant debris of toppled plant; larvae are 2.5–5.0 cm (1–2 in) in length; larvae may exhibit a variety of patterns and coloration but will usually curl up into a C-shape when disturbed.
Remove all plant residue from soil after harvest or at least two weeks before planting, this is especially important if the previous crop was another host such as alfalfa, beans or a leguminous cover crop; plastic or foil collars fitted around plant stems to cover the bottom 3 inches above the soil line and extending a couple of inches into the soil can prevent larvae severing plants; hand-pick larvae after dark; spread diatomaceous earth around the base of the plants (this creates a sharp barrier that will cut the insects if they try and crawl over it); apply appropriate insecticides to infested areas of garden or field if not growing organically.
An infested common bean leaf showing tracts of the leaf miner Liriomyza sp.
leafminer fly (Liriomyza sp.) adult
Larvae of leafminer
vegetable leafminer (Liriomyza sativae) on bean leaves
vegetable leafminer (Liriomyza sativae) adult
leafminer fly (Liriomyza sp.) pupa
Leafminer damage on bean plant leaf
Tunnels caused by leafminer
Thin, white, winding trails on leaves; heavy mining can result in white blotches on leaves and leaves dropping from the plant prematurely; early infestation can cause fruit yield to be reduced; adult leafminer is a small black and yellow fly which lays its eggs in the leaf; larvae hatch and feed on leaf interior.
Check transplants for signs of leafminer damage prior to planting; remove plants from soil immediately after harvest; only use insecticides when leafminer damage has been identified as unnecessary spraying will also reduce populations of their natural enemies.
Bean common mosaic virus (BCMV)
Bean common mosaic necrosis virus (BCMNV)
Bean common mosaic virus symptoms on bean foliage
A common bean plant showing symptoms of black root wilting caused by the Bean Common Mosaic Virus (BCMV).
Pods of common beans showing symptoms of black root necrosis caused by the Bean Common Mosaic Virus (BCMV).
Drybean leaflets showing symptoms
Bean yellow mosaic virus on a bean leaflet showing the mosaic pattern as caused by the Bean Common Mosaic Virus (BCMV).
A common bean leaf of an infected plant showing leaf cupping and mosaic
A common bean plant showing symptoms of black root necrosis caused by the Bean Common Mosaic Virus (BCMV).
Dry bean plants showing symptoms of Bean Common Mosaic Virus.
Bean yellow mosaic on a bean leaflet showing the mosaic pattern
A common bean plant showing symptoms of stunting caused by the Bean Common Mosaic Virus (BCMV)
Leaves of a common bean plant showing symptoms of primary leaf necrosis caused by the Bean Common Mosaic Virus (BCMV).
Mottled dark and light green patterns on leaves; leaves may be distorted; yellow dots may be present on leaves; growth of plant may be reduced.
Plant only virus-free seed; plant resistant varieties.