Dry Bean

Aphids vector bean mosaic virus, which is a bigger threat to a seed-saved dry-bean crop than the feeding itself. A reflective mulch under young plants deters them.

Dense clusters of tiny insects packed onto shoot tips, flower buds, and the undersides of young leaves. Curled, cupped, or distorted new growth that never opens properly. A sticky shine on the leaves - and on whatever sits under the plant - that later goes black with sooty mold. Tiny white cast skins left behind where a colony has been feeding. Ants running steadily up and down the stems, which is often the first thing you notice. Mottled, streaked, or misshapen leaves that do not grow out can mean a virus the aphids brought with them rather than the feeding itself.

Knock the colonies off with a hard jet of water and repeat every few days - on most plants that alone ends it. Pinch out or prune off the worst-infested tips rather than treating the whole plant. If colonies keep rebuilding, spray insecticidal soap or horticultural oil directly onto the insects, covering leaf undersides, and repeat weekly until they are gone; treat early or late in the day, and never spray a wilted or heat-stressed plant. Avoid broad-spectrum insecticides - they kill the ladybugs, lacewings, and parasitic wasps that were about to solve the problem for you, and aphid numbers usually come back worse afterward. Anything you spray must be labeled for the plant you are treating; follow that label and observe its pre-harvest interval. On anything you eat, wash leaves, heads, and buds well before use, since aphids hide down in crowns, folds, and tight growth.

Go easy on nitrogen: the soft, lush growth that heavy feeding produces is exactly what aphids breed on. Check new growth once a week through spring and early summer so you catch colonies while they are still small, and rub the first few out with your fingers. Leave flowering plants nearby and skip broad-spectrum sprays - ladybugs, lacewings, hoverflies, and parasitic wasps do most of this work for free, and they only stay if there is something for them to eat. Keep ants off the plant where you can, since they protect aphids from those predators. Water steadily so plants are not stressed, and check any new plant over before you bring it home or move it indoors, since aphids usually arrive on something else.

Aphids are small soft-bodied sap-suckers - green, black, gray, pink, or waxy white, and mostly wingless - that gather in dense colonies on the tenderest new growth: shoot tips, buds, and the undersides of young leaves. They breed extremely fast in mild weather, so a few can become hundreds inside a week. Their feeding curls and distorts soft growth, and the sticky honeydew they excrete coats everything below and turns black with sooty mold. Ants often farm and defend the colonies for that honeydew. A few aphids are normal on almost any plant and a healthy plant shrugs them off; only dense, persistent colonies do real damage, and some aphids also spread plant viruses as they feed.

Corrected from the draft's truncated 'common-bean-mosaic-viru' slug; seed-borne, so clean seed and resistant varieties matter for saved-seed crops.

Mottled light-and-dark green leaves, puckered or curled foliage, stunted plants, and reduced pod set.

No cure - rogue out infected plants to protect the rest, and don't save their seed.

Grow resistant varieties (many carry BCMV resistance), control aphids, use clean seed, and remove infected plants promptly.

A group of viruses (notably Bean Common Mosaic Virus) that mottle and distort leaves and stunt plants; spread by aphids and carried in infected seed.

Defoliation during pod fill directly shrinks the dry-bean yield.

Fuzzy spiny yellow larvae and neat clusters of yellow eggs on the leaf undersides, lacy skeletonized leaves with only the veins left, and coppery black-spotted adults on the foliage. The larvae are usually well established underneath before the adults become obvious, so turn the leaves over.

Hand-crush eggs and larvae on the leaf undersides - done every day or two while the pods are filling, this alone controls a home planting. Insecticidal soap or neem knocks back a heavy larval outbreak, and the parasitic wasp Pediobius is available for large plantings. Do not spray anything onto open flowers.

Float row cover over young plants, scout leaf undersides weekly from midsummer and crush the egg clusters before they hatch, grow early varieties that finish before peak beetle season where you can, clean up bean-family debris in fall, and rotate the bean bed.

A coppery, black-spotted beetle that looks like an oversized ladybug and is in fact a member of the same family - but this one eats plants. The spiny yellow larvae do most of the damage, feeding on the undersides of bean-family leaves and skeletonizing them into lace, which cuts the photosynthesis that fills the pods. Both adults and larvae feed, and over a long season the generations stack up.

Defoliation during pod fill directly shrinks the dry-bean yield, which is the entire crop here. A shared bean-family disease, kept on its own slug so it stays distinct from cereal and allium rusts.

Small raised rusty-orange pustules ringed with yellow, mostly on the leaf undersides and usually starting low in the plant where humidity is highest, followed by yellowing, browning and early leaf drop once it takes hold.

Strip the worst-affected leaves early, starting with the lower ones. Sulfur slows the spread in a wet season; copper is not effective against rust. A late infection often still allows a full harvest, and fungicides are rarely needed in a home garden.

Grow resistant or tolerant varieties where they are offered, space and train for airflow, water at the base so the leaves stay dry, and rotate beans on a two to three year cycle. Remove crop debris after harvest rather than leaving it to carry the fungus over.

A fungal disease (Uromyces) of bean-family plants, producing raised rusty orange-brown pustules on the leaves and sometimes the stems, mostly on the undersides and ringed with yellow. Heavy infection browns and drops the foliage, and losing leaf area during pod fill directly shrinks the crop. It is worst in warm, humid weather and wherever the leaves stay wet.