Pests
Symptoms Thick clusters of tiny black insects packed onto the growing tips, flower stalks, and undersides of the top leaves, showing up as it warms up in spring. They curl and stunt the new growth, knock off flowers, and leave a sticky coating that turns black and moldy. This is the classic fava pest, and it also spreads plant viruses, so catch it early.Dense colonies of small, matte-black aphids packed onto the growing tips, flower trusses, and the undersides of the upper leaves, arriving as the weather warms. Heavy feeding curls and stunts the new growth, drops blossoms, and coats the plant in sticky honeydew that turns to black sooty mold. The black bean aphid is the signature pest of favas, and beyond direct damage it spreads bean and legume viruses. Cause The black bean aphid, a dark, soft-bodied aphid that multiplies very fast on favas as the weather warms. It swarms the tender growing tips before helpful insects like ladybugs can catch up, and favas are its favorite host.The black bean aphid (Aphis fabae), a dark green to black, soft-bodied aphid with a dark head and cornicles that builds up explosively on favas as spring warms. It reproduces very fast, so colonies form on the succulent growing tips before natural enemies catch up, which is why favas are its namesake host. Organic treatment Once the lowest pods have set, pinch off the soft growing tip of each plant, which is where the aphids gather, and you remove most of the colony at once. Blast the rest off with a strong spray of water or use insecticidal soap. Ladybugs and other helpers usually clean up the rest. Deal with them early, because they spread viruses.Once the lower pods have set, pinch out the soft growing tip of each plant: this removes the tender shoot the aphids concentrate on and the bulk of the colony with it, a standard broad-bean tactic. Knock remaining colonies off with a strong spray of water or treat with insecticidal soap on contact. Ladybugs, lacewings, and parasitic wasps usually finish the job; act early, since the real risk is virus spread. Prevention Plant early so the favas are strong and podding before the aphids peak, and try planting summer savory alongside as tradition suggests. Do not overfeed with fertilizer, since soft new growth is exactly what aphids like, and lay reflective mulch to confuse them. Pinch off the growing tips once the lower pods have set to take away their favorite spot.Sow early so the crop is well grown and podding before the spring aphid flights peak, and grow summer savory nearby by tradition. Avoid overfeeding with nitrogen, which produces the soft, lush growth aphids favor, and lay reflective mulch to disorient them. Conserve natural enemies by not spraying broadly, and pinch the tips promptly once pods have set.
Symptoms Neat half-circle notches chewed out of the edges of the leaves on young plants, lining up into a scalloped look. The leaf notching alone does not hurt a strong plant much, but the grubs feed underground on the root nodules, which cuts the plant's own nitrogen supply and can slow a young crop.Neat, half-moon notches chewed from the leaf margins of young plants, which line up into a scalloped edge as the small weevils feed. The above-ground notching is mostly cosmetic on established plants, but the hidden damage matters: the larvae feed underground on the root nodules, which inhibits nitrogen fixation and can set back a young, cool-soil crop. Cause The pea and bean weevil (Sitona lineatus), a small brown striped weevil. The adults spend the winter nearby and move onto young favas and peas, and their grubs feed on the root nodules underground. Where winters are mild they are around as soon as the plants come up.The pea and bean weevil (Sitona lineatus), an elongate light-brown weevil with pale stripes down its back and a short snout. Adults overwinter and move onto favas and peas as they emerge; the larvae develop on the root nodules. In mild-winter regions the adults do not fully diapause, so they are present as soon as the crop comes up, and larval feeding is worst from spring into early summer. Organic treatment Healthy, fast-growing plants shrug off the leaf notching, so keep young favas growing well. A light row cover over the seedlings keeps the weevils off while the plants are small and most at risk. Encouraging beneficial ground insects helps keep them in check.Vigorous plants outgrow the leaf notching, so a strong, well-fed stand is the main defense; keep young plants growing steadily. A floating row cover over emerging seedlings keeps adults off during the vulnerable stage. Handpicking is impractical, but conserving ground beetles and other natural enemies helps hold numbers down. Prevention Plant so the seedlings come up and grow quickly past the tender stage, and move your favas and peas to a new spot each year. Clear away old plant debris where the weevils hide over winter, and cover young seedlings with a row cover if these weevils are a problem where you are.Sow into warm-enough soil so seedlings grow away quickly past the vulnerable stage, and rotate favas and peas away from last year's ground. Clear crop debris that shelters overwintering adults, and protect emerging seedlings with a row cover where the weevil is established.
Symptoms The seed comes up thin and patchy, with gaps in the row, and if you dig into a gap you find a rotted seed with small pale maggots in it. Any seedlings that do come up may be weak. It is worst when the seed is sown into cold, wet soil that has a lot of fresh compost or crop residue in it.Poor, patchy emergence with gaps in the row, and seeds that rot in the ground before sprouting; digging up a gap turns up a hollowed, rotting seed with small, pale maggots inside. Seedlings that do emerge may be weak or damaged. The damage is worst in cold, wet soil rich in fresh organic matter, exactly the conditions favas are often sown into after a cover crop. Cause The bean seed fly (also called seedcorn maggot), a small gray fly whose maggots tunnel into the sprouting seed. The flies are attracted to rotting compost and manure, and they attack most when cold, wet soil makes the seed sit for a long time before it sprouts.The bean seed fly, or seedcorn maggot (Delia platura), a small gray fly whose maggots burrow into germinating bean seed and prevent it from emerging. The flies are drawn to decaying organic matter and lay eggs in cool, moist, recently worked soil; cold, wet conditions that slow germination leave the seed exposed to attack for longer and are the main risk factor. Organic treatment You cannot save a seed that has already been eaten out, so replant the gaps once the soil is warmer and drains better and the new seed can sprout quickly. Planting into workable, warmer soil rather than cold mud is the main way to avoid it.There is no rescue for a seed already hollowed out; replant the gaps once the soil is warmer and drier so the new seed germinates fast and outruns attack. Sowing shallowly into well-drained, workable soil, and waiting for the ground to warm before sowing where the fly is a known problem, is the practical control. Prevention Plant into workable, well-drained soil, not cold soggy ground, and let any fresh compost or manure rot down well before you sow rather than digging it in right before planting. Getting the seed to sprout quickly is the best protection, so favor warmer soil and shallow planting.Sow into a firm, well-drained seedbed once the soil is workable rather than cold and saturated, and let coarse fresh residue or manure break down well before sowing rather than turning it in just ahead of the crop. Shallow sowing that speeds emergence, and warmer soil, both shorten the window when the seed is vulnerable.
Diseases
Symptoms Small round reddish-brown spots, the color of chocolate, scattered over the leaves, stems, and flowers. In dry weather they stay as small spots, but in a wet spell they spread and darken, killing leaves, dropping the flowers, and in bad cases collapsing the whole plant. It is the most serious fava disease and hits hardest on crowded, overwintered plants in late winter and spring.Small, round, red-brown (chocolate-colored) spots scattered over the leaves, stems, and flowers. In dry spells the spots stay small and discrete, but in prolonged wet weather they enlarge, merge, and darken, killing whole leaves, shedding blossoms, and in severe attacks collapsing the entire plant. It is the signature and most damaging disease of favas, and it is worst on dense, overwintered crops from late winter on. Cause A fungus (Botrytis fabae) that thrives in cool, damp, crowded conditions when the leaves stay wet for a long time. It spreads on the wind and can carry over on old plant debris and infected seed, so a wet spring on a thick, overwintered stand is when it does the most harm.The fungus Botrytis fabae (with Botrytis cinerea also involved), favored by cool, damp, overcrowded conditions and long leaf wetness. Spores are airborne and the fungus can carry over on infected debris and on the seed, so a wet spring on a dense autumn-sown stand is the classic setup for a damaging outbreak. Organic treatment There is no home garden spray for chocolate spot, so you manage it by keeping plants open and dry. At the first spots, thin crowded growth and pull weeds to move air through the planting, pick off the worst leaves, and stay out of the patch when the plants are wet. If an overwintered stand is badly hit, pick what you can and pull the plants.There are no fungicides available to home gardeners for chocolate spot, so management is cultural. At the first spots, improve airflow by thinning crowded growth and pulling weeds, remove the worst-affected leaves, and avoid working among wet plants. On a badly hit overwintered stand, harvesting what is usable and clearing the crop is often the practical choice. Prevention Space plants well and keep the planting open so air moves through it, and avoid damp, shady, crowded spots, which are exactly what the disease likes. Plant into well-drained soil, do not sow too thickly, do not save seed from an infected crop, and clear away old plant debris after harvest. Move your favas to a new spot on a three-to-four-year cycle.Give plants plenty of room and maximize airflow with wider spacing; avoid damp, sheltered sites and dense stands, the conditions the disease needs. Ensure good drainage, sow at a sensible rate rather than thickly, do not save seed from an infected crop, and remove crop debris and nearby common vetch that can harbor it. Rotate favas on a three-to-four-year cycle.
Symptoms Small, dusty, dark-brown spots (pustules) scattered over the leaves and stems, often with a faint yellow ring around each, that leave a rusty smudge when rubbed. It usually turns up later, in the warmer weather of mid to late season. It is less serious than chocolate spot, but a heavy attack can strip the leaves and weaken plants as they finish up.Small, dusty, dark-brown pustules scattered over the leaves and stems, each often ringed by a faint yellow halo; rubbing them leaves a rusty smudge. It usually appears later in the season, in warmer weather from around midsummer, and while it is less destructive than chocolate spot, a severe attack can defoliate plants and sap their vigor as they finish. Cause A rust fungus (Uromyces viciae-fabae) that lives on favas and spreads on the wind in warm weather. Its spores survive on old plant debris and seed over winter, so it comes back where favas are grown in the same spot year after year.The rust fungus Uromyces viciae-fabae, which completes its life cycle on favas and spreads by airborne spores in warm conditions. It keeps the infected leaf tissue alive to feed on, and its end-of-season spores survive in crop debris and on the seed, so it returns where favas are grown repeatedly without a break. Organic treatment There is no home garden spray for broad bean rust, so keep the plants open and airy with wider spacing and avoid damp, sheltered spots. Pull off badly spotted leaves. Since rust shows up late, an early planting usually finishes its pods before it matters, and clearing away the old plants at the end helps.There are no fungicides available to home gardeners for broad bean rust, so cultural control is the mainstay. Improve airflow with wider spacing, avoid humid, sheltered sites, and remove badly affected leaves. Because rust arrives late, an early-sown crop often finishes its pods before rust does real harm; clear and destroy the debris at the end. Prevention Plant early so the crop finishes before the warm weather that brings on rust, give plants room for air to move, and avoid damp, crowded spots. Clear away and destroy the old plants at season's end, since the spores survive on debris and seed, and move your favas to a new spot each year.Sow early so the crop matures before the warm midsummer weather that drives rust, space plants for airflow, and avoid humid, crowded sites. Destroy infected plant material at the end of the season, since the spores overwinter in residue and on seed, and rotate favas so the disease does not build up in one bed.
Symptoms The big seeds rot before they come up, or seedlings flop over at a pinched, water-soaked spot near the soil, leaving gaps in the row. On older plants the roots rot, the lower leaves yellow, and growth stalls. It is worst in cold, wet, poorly drained soil that makes the seed sit too long before sprouting.Large seed that rots before emerging and seedlings that damp off at a pinched, water-soaked stem base, leaving gaps in the row; on older plants a root-rot complex yellows and stunts the vines and rots the lower stem and roots. Damage is worst in cold, wet, poorly drained soil that slows germination and keeps seedlings vulnerable, and it overlaps with bean seed fly injury in the same conditions. Cause A group of soil fungi and water molds that attack the seed, roots, and seedlings. Cold, soggy soil and damaged roots let them in, and they build up where beans and favas are grown too often in the same place. You manage this by preventing it, not by spraying.A complex of soilborne fungi and water molds (Pythium, Rhizoctonia, Fusarium, and others) that attack seeds, roots, and seedlings. Cold, saturated soil and injured roots at sowing set the stage, and the organisms build up in ground cropped to legumes too often, so drainage and rotation are the levers rather than treatment. Organic treatment There is no saving seed or seedlings that have already rotted, so replant the gaps once the soil is warmer and drains better. Pulling affected plants and improving drainage help, but the main thing is preventing it, since these organisms live in the soil.There is no rescue for rotted seed or collapsed seedlings; replant the gaps into warmer, better-drained conditions once the soil has dried. Removing affected plants and improving drainage limits further loss, but because the organisms are already in the soil, prevention is the real control. Prevention Plant in well-drained soil or raised beds instead of cold, wet, low spots, and never sow into soggy ground. Avoid damaging the roots when planting, move your favas and beans around the garden on a three-to-four-year cycle, and clear away the old plants after harvest.Sow into well-drained ground or raised beds rather than cold, low, wet spots, and do not sow into waterlogged soil. Avoid root injury at planting, keep beds in a three-to-four-year rotation away from legumes to limit buildup, and clear crop debris after harvest.
Symptoms Pale, fuzzy patches on the top of the leaves, with a grayish, velvety mold on the underside in damp weather. The growing tips can twist and discolor, and a bad case means fewer pods. It shows up in cool, humid weather and is more of a spring problem.Pale, blurry patches on the upper surface of the leaves, with a grayish to mauve, velvety mold on the corresponding underside in damp weather. Growing points can become distorted and discolored, and heavy infection reduces pod set. It develops in cool, humid conditions and tends to be more of a problem on the spring crop. Cause A downy mildew fungus that likes cool, humid weather and wet leaves, and that can survive in the soil and on the seed for years. Crowded, damp plantings and growing favas in the same spot repeatedly make it worse.The downy mildew fungus, which favors cool, humid conditions and long leaf wetness and can persist in the soil and on seed for years. Crowded, damp plantings and repeated cropping in the same ground favor it. Organic treatment Manage it by keeping plants open and dry: thin crowded growth, pull off affected leaves and tips early, water at the soil rather than overhead, and stay out of the patch when it is wet. Clear away the old plants at the end of the season.Home management is cultural: improve airflow by thinning and wider spacing, remove affected leaves and growing tips early, avoid overhead watering, and stay out of the planting when wet. Clear infected debris at the end of the season. Prevention Give plants room so air moves through, avoid damp, shady spots, and water the soil rather than the leaves. Do not save seed from an infected crop, move your favas around the garden on a three-to-four-year cycle, and clear away debris, since the fungus can live on in the soil and seed.Space plants for airflow, avoid damp, sheltered sites, and water at the soil rather than overhead. Do not save seed from an infected crop, rotate favas on a three-to-four-year cycle, and remove crop debris, since the fungus can persist in soil and on seed.
