Pests
Symptoms Clusters of small, soft green insects packed onto the growing tips, flower stems, and undersides of the leaves. They curl and yellow the new growth and stunt the plants, and they leave a sticky residue. The bigger problem is that pea aphids spread virus diseases from plant to plant, so they are worth catching early.Colonies of soft, pinhead-sized green aphids clustered on the growing tips, flower stalks, and leaf undersides. Heavy feeding curls and yellows the new growth, stunts the vines, and can drop blossoms; a sticky honeydew and sooty mold may follow. Most important, pea aphids transmit the virus diseases of peas, including pea enation mosaic, so even modest numbers matter. Cause The pea aphid, a large green aphid that multiplies quickly in the cool weather of spring and fall when peas are growing. It builds up fast, before helpful insects like ladybugs catch up.The pea aphid (Acyrthosiphon pisum), a large green aphid that builds up fast in the cool, mild weather of spring and fall, exactly the seasons peas grow. It reproduces rapidly, so colonies form before natural enemies catch up. Organic treatment Blast the colonies off with a strong spray of water, or use insecticidal soap, which works on contact. Start as soon as you see them, while there are only a few. Ladybugs and other helpful insects usually finish the job. Since aphids spread viruses, it is worth dealing with them early.Knock colonies off with a strong spray of water, or treat with insecticidal soap, which controls aphids on contact; begin as soon as colonies are found, while numbers are low. Ladybugs, lacewings, and parasitic wasps usually bring populations down on their own. Because the real risk is virus transmission, act early rather than waiting for visible damage. Prevention Lay down reflective mulch, which confuses aphids and cuts the viruses they spread, and pull nearby weeds that shelter them. Do not overfeed with fertilizer, since the soft new growth is exactly what aphids like. Where pea viruses are common, plant a resistant variety like Oregon Sugar Pod II.Lay reflective mulch, which disorients aphids and reduces both feeding and virus spread, and control nearby weeds and clover that harbor them. Avoid overfeeding with nitrogen, which produces the soft, lush growth aphids favor, and choose virus-resistant varieties such as Oregon Sugar Pod II where pea viruses are a known problem.
Symptoms Little notches chewed out of the leaf edges of young plants, and beetles on the flowers in spring. The hidden damage is worse: the grubs tunnel into the peas forming inside the pods, leaving tiny round holes in the dried seeds. Holes in saved seed are the tell. The pea weevil eats only peas.Small notches chewed from the leaf margins of young plants in spring, and adults feeding on the blossoms. The real damage is hidden: larvae bore into the developing seeds inside the pods and feed there, leaving tiny round exit holes in the dried peas. Saved seed with holes is the giveaway. The pea weevil feeds only on peas (Pisum). Cause The pea weevil, a small brown beetle that feeds only on peas. The adults spend the winter in garden trash, move in when the peas flower to lay eggs on the young pods, and the grubs grow up inside the seeds. There is one generation each year.The pea weevil (Bruchus pisorum), a small brownish beetle whose host range is peas alone. Adults overwinter in debris and trash, move into the crop at bloom to lay eggs on young pods, and the larvae develop inside the seeds. There is one generation a year. Organic treatment Watch for the beetles while the peas are flowering, which is when they lay eggs. Picking them off and covering the plants with a light row cover at flowering both help. At the end of the season, check dried peas for tiny round holes before you save seed, and freezing saved seed for a few days kills any grubs inside.Monitor for adults during bloom, when egg-laying begins. In a home patch, handpicking and floating row cover over the crop at flowering reduce egg-laying. At season's end, inspect dried peas for the small round exit holes before storing seed; freezing saved seed for several days kills any larvae inside. Prevention Clear away and destroy the old pea plants after harvest so the beetles have nowhere to overwinter, and move your peas to a new spot each year. Do not save seed that has holes in it. Planting early so the pods finish before the beetles get busy also helps.Clean up and destroy pea debris after harvest to remove overwintering shelter, and rotate peas away from last year's bed. Do not save or replant seed showing exit holes. Where the weevil is established, an early sowing that finishes pod fill before peak adult activity escapes the worst.
Symptoms Cutworms cut off young pea seedlings right at the soil line overnight, so you find plants toppled over and gaps in the row. Armyworms are smooth caterpillars that chew the leaves and sometimes the pods, and they can show up in numbers. Both feed at night and hide during the day.Cutworms sever young seedlings at or just below the soil line overnight, leaving toppled plants and thinned rows in spring. Armyworms are smooth caterpillars that chew foliage and can move through a planting in numbers, skeletonizing leaves and nicking pods. Both feed mostly at night and hide in the soil or debris by day. Cause Several kinds of night-feeding caterpillars: cutworms and armyworms, the young of different moths. They come in from weedy or grassy areas, and young seedlings are the most at risk.Several night-feeding caterpillars, including cutworms (the larvae of various moths) and beet or western yellowstriped armyworms. They overwinter or move in from weedy ground and grassy cover, and seedlings are the most vulnerable stage. Organic treatment Pick the caterpillars off in the evening or early morning, and dig a little around fallen seedlings to find the curled-up cutworm. A collar of cardboard or foil around a seedling blocks cutworms, and a Bt spray controls young armyworms on the leaves. A light row cover keeps the moths from laying eggs.Handpick caterpillars in the evening or early morning, and check the soil around toppled seedlings for the curled cutworm. A cardboard or foil collar around a seedling stops cutworms; Bacillus thuringiensis (Bt) controls young armyworms on the foliage. A floating row cover keeps egg-laying moths off the planting. Prevention Clear weeds and tall grass before planting so the moths have fewer places to lay eggs, and turn the soil a couple of weeks before sowing to expose the grubs. Keep the edges of the bed weeded, and cover young seedlings with a row cover if these caterpillars are a problem where you are.Clear weeds and grassy cover before sowing to remove egg-laying sites, and turn the bed a couple of weeks ahead of planting to expose and dry out resident larvae. Keep row edges weed-free through the season, and protect emerging seedlings, the vulnerable stage, with a row cover where these caterpillars are a known problem.
Symptoms Fine silvery streaks and pale flecks on the leaves and pods, with tiny dark specks, where the slender insects scrape the surface and feed. Bad infestations twist the new growth and leave scars on the pods. Thrips can also spread some viruses.Fine silvery or whitish scarring and flecking on leaves and pods, with tiny dark specks of excrement, as the slender insects rasp the surface and feed on the released sap. Heavy feeding distorts new growth and can scar pods cosmetically. Thrips also vector some plant viruses. Cause Thrips, slender insects much smaller than an aphid that build up in warm, dry weather toward the end of the pea season. They scrape the surface of the plant and feed on the sap.Several thrips species, slender insects a fraction the size of an aphid that build up in warm, dry stretches late in the pea season. They rasp the plant surface and feed on the sap that wells up. Organic treatment Peas usually shrug off a little thrips damage. If they build up, a strong spray of water and insecticidal soap knock them back, and helpful insects pitch in. Keep the plants watered and unstressed, since dried-out peas are more likely to be hit.Peas usually outgrow light thrips feeding without treatment. Where numbers climb, a strong spray of water and insecticidal soap reduce them, and natural enemies such as minute pirate bugs and lacewings help. Keep plants unstressed and well watered, since drought-stressed peas are more prone. Prevention Pull nearby weeds that shelter thrips, lay reflective mulch to confuse them, and keep the soil evenly moist so the plants are not stressed. Most home pea crops are done before thrips become a real problem.Control weeds that harbor thrips, lay reflective mulch to disorient them and reduce virus spread, and keep moisture even so plants are not drought-stressed. Most home pea crops finish before thrips become a real problem.
Diseases
Symptoms A white to gray powdery dust that starts as spots on top of the leaves and spreads over the leaves, stems, and pods. The leaves yellow and dry out, the vines weaken, and the pods can be spotted. It is the classic late-season pea problem, showing up as the weather warms and dries toward the end of the spring crop.A white to grayish powdery coating that starts as small spots on the upper leaf surfaces and spreads to cover leaves, stems, and pods. Affected leaves yellow and dry, vines lose vigor, and pods may be spotted or off-flavored. It is the classic late-season pea disease, arriving as the spring crop runs into warmer, drier weather. Cause A fungus (Erysiphe pisi) that thrives in warm days, cool nights, and dry leaves, which is exactly the weather at the end of the pea season. It spreads on the wind and moves fast once it starts, so catching it early and planting resistant varieties matter most.The fungus Erysiphe pisi, favored by warm days, cool nights, and dry foliage, the conditions that arrive late in the pea season. Spores spread on the wind, and the disease moves fast once established, which is why early control and resistant varieties matter most. Organic treatment Powdery mildew is easiest to handle the moment you first see it; once it covers the leaves, it is hard to stop. Pick off the worst leaves and open up the planting for airflow. A sulfur spray started early and repeated per the label helps. If the spring crop is nearly finished, the simplest move is to pick what is ready and pull the plants.Powdery mildew is best managed at the very first signs; once it covers the leaves and yellowing sets in, control is difficult. Remove the worst-affected leaves and improve airflow. Sulfur or a labeled biofungicide, begun early and repeated per the label, suppresses it. On a spring crop that is nearly done, harvesting promptly and pulling the planting is often the practical choice. Prevention Plant a resistant variety, which is the best defense: Oregon Sugar Pod II and many newer snow peas resist powdery mildew. Plant early so the crop finishes before the mildew weather arrives, give the plants room and a trellis so air moves through them, and stay out of the patch when the vines are wet.Choose resistant varieties, the single most effective step: Oregon Sugar Pod II and many modern snow peas carry powdery mildew resistance. Sow early so the crop finishes pod fill before the late-season mildew weather, give plants room and a trellis for airflow, and avoid working among wet vines.
Symptoms The lower leaves turn yellow and the yellowing creeps up the plant, which becomes stunted, curls, and wilts. If you cut the lower stem, the tissue inside is stained reddish or orange. Affected plants often die before making a crop. It shows up in patches and gets worse as the soil warms.A yellowing of the lower leaves that progresses up the plant, with downward curling, stunting, and wilting; a cut through the lower stem shows a reddish or orange discoloration of the water-conducting tissue. Plants often die before pod fill. Symptoms appear in patches and worsen as the soil warms. Cause A fungus that lives in the soil and enters through the roots, clogging the plant's plumbing. It survives in the soil for years and likes warm soil. Once it is in a bed you cannot get rid of it, so the answer is resistant varieties and moving your peas around.The soilborne fungus Fusarium oxysporum f. sp. pisi, which enters through the roots, plugs the vascular system, and persists in the soil for years. Several races exist. Warm soil favors it, and once a bed is infested the fungus cannot be eradicated, so resistant varieties and rotation are the management. Organic treatment There is no cure once a plant is infected; pull and throw away (do not compost) the affected plants. You manage this one by preventing it, with resistant varieties and rotation, not by spraying.There is no cure for infected plants; remove and destroy them to limit buildup. Management is preventive: the disease is handled through resistant varieties and rotation, not treatment. Prevention Plant a wilt-resistant variety, which most modern snow peas are (Oregon Sugar Pod II, Dwarf Gray Sugar, Mammoth Melting Sugar all resist it). Move your peas to a new spot on a three-to-four-year cycle, improve drainage, and avoid carrying infected soil from bed to bed.Plant Fusarium-resistant varieties, which are widely available (Oregon Sugar Pod II, Dwarf Gray Sugar, and Mammoth Melting Sugar all carry wilt resistance). Rotate peas on a three-to-four-year cycle away from infested ground, improve drainage, and avoid moving infested soil between beds.
Symptoms Seeds that rot before they come up, and seedlings that flop over at a pinched, water-soaked spot near the soil. On bigger plants the roots rot, the vines stunt, and the lower leaves yellow and die. It is worst in cold, wet, poorly drained soil that makes the seed sit too long before sprouting.Seed that rots before emerging, and seedlings that damp off, collapsing at a water-soaked, pinched stem base. On older plants the root rot complex stunts the vines, yellows and kills the lower leaves, and rots the roots and lower stem brown. Damage is worst in cold, wet, poorly drained soil that slows germination and keeps seedlings vulnerable. Cause A group of soil fungi and water molds (including Pythium, Rhizoctonia, and Aphanomyces) that attack seeds, roots, and seedlings. Cold, soggy soil and damaged roots at planting let them in, and they build up where peas are grown too often in the same spot.A complex of soilborne fungi and water molds, chiefly Pythium, Rhizoctonia, Fusarium solani, and Aphanomyces euteiches. Cold, saturated soil and root injury at planting set the stage; Aphanomyces in particular builds up in beds cropped to peas too often and severe infections kill plants outright. Organic treatment There is no saving seed or seedlings that have rotted; replant 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 into warmer, better-drained conditions once the soil has dried. Removing affected plants and improving drainage limits further loss, but prevention is the real lever since the organisms are already in the soil. Prevention Plant in well-drained soil or raised beds instead of cold, wet, low spots, and never sow peas into soggy ground. Avoid damaging the roots when planting, move your peas 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 peas into waterlogged soil. Avoid root injury at planting, rotate peas on a three-to-four-year cycle to keep Aphanomyces down, and clear crop debris after harvest. Some varieties offer partial root-rot tolerance.
Symptoms Brown to purple-black spots and streaks on the leaves, stems, and pods, sometimes with a blackened stem base. Sunken spots on the pods can carry the disease into the seed. It shows up in cool, wet spring and fall weather and rides in on infected seed and old plant debris.Brown to purplish-black spots and streaks on leaves, stems, and pods, often with darker margins; a blackening at the base of the stem (foot rot) in one form, and sunken lesions on the pods that can carry the fungus into the seed. It develops in cool, wet spring and fall weather and is carried on infected seed and debris. Cause A group of related fungi that survive on infected seed and on old pea plants left in the soil. Cool, wet weather and splashing water spread them. Once they are on the seed, they travel with it to the next planting.A complex of related fungi (the Ascochyta blight complex, including Ascochyta pisi and Mycosphaerella pinodes). The fungi survive on infected seed and on pea debris in the soil, and cool, wet conditions with splashing water drive infection and spread. Organic treatment You cannot cure tissue that is already infected; pull and throw away (do not compost) affected plants and all the old debris to slow it down. For a home garden, prevention does most of the work, since the disease travels on seed and old plants.There is no cure for infected tissue; remove and destroy affected plants and all debris to limit spread. Cultural control is the mainstay for a home crop, since the disease is seed- and debris-borne. Prevention Plant certified disease-free seed and do not save seed from an infected crop. Clear away all the old pea plants after harvest, and do not grow peas in that spot for at least three to four years. Water at the base, not overhead, and stay out of the patch when the vines are wet.Plant certified disease-free seed and do not save seed from an infected crop. Remove all pea debris after harvest and rotate peas off the ground for a minimum of three to four years before returning. Avoid overhead watering and working among wet vines, which splash and carry the fungus.
