Pests
Symptoms You will see pale, winding tunnels in the leaves that widen into large tan blisters or blotches, with the green skin of the leaf intact above and below. Hold a leaf to the light and you can see the tiny maggot working inside. Since you eat chard leaves, this ruins the damaged parts.Slender, winding mines enlarge into translucent tan blotches; because the crop is the leaf, even light feeding downgrades it, and heavily mined chard is unusable. The pale legless maggots are visible inside the leaf against the light. Cause A small fly lays eggs on the underside of the leaves, and the maggots that hatch tunnel inside, eating between the top and bottom layers. Chard, beets, and spinach are its favorites, which is why it helps not to plant them together.The beet and spinach leafminer (Pegomya species) overwinters as pupae in the soil; females lay rows of white eggs on leaf undersides, and the maggots tunnel between the leaf surfaces. There are several overlapping generations a season on chard, beets, spinach, and goosefoot weeds, the reason these relatives are rotated and spaced apart. Organic treatment Once a maggot is inside a leaf, sprays do not reach it well, so pick off and destroy mined leaves as soon as you see them, before the maggots drop to the soil. Crushing the maggot inside the leaf works too. Keep the plant healthy and it will outgrow light damage.Insecticides reach larvae inside the leaf poorly, so rely on cultural control: pick and destroy mined leaves before larvae drop to pupate, and crush maggots in the leaf. Vigorous, evenly watered plants outgrow light damage, and naturally occurring parasitic wasps usually keep numbers in check. Prevention Cover the plants with a light row cover right after sowing so the flies cannot lay eggs, pull nearby weeds like lambsquarters that host the pest, and move chard away from where you grew chard, beets, or spinach last year.Exclude the egg-laying flies with floating row cover from sowing, control goosefoot weeds (lambsquarters, chickweed) that host the pest, rotate away from where chard, beets, or spinach grew, and remove the first mined leaves promptly to break the cycle.
Symptoms Clusters of tiny soft green or black insects collect on the undersides of leaves and on new growth, leaving leaves curled, yellowed, and sticky. They can hide down in the crinkled leaves and along the stalks, and they can spread plant viruses.Colonies of soft-bodied aphids on leaf undersides, new growth, and along the petioles distort and yellow the foliage; honeydew and sooty mold downgrade the crop, and the crinkled leaves of savoyed types shelter colonies. Aphids also transmit virus diseases. Cause Aphids are small insects that suck sap from the plant. They breed quickly, especially on soft growth from too much nitrogen, and fly in from weeds and other plants.Several aphid species feed on chard sap; populations build fastest in mild weather and on the soft, lush growth that excess nitrogen produces, with winged forms moving in from weeds and other crops. Organic treatment Blast them off with a strong spray of water, which often does the trick, or use insecticidal soap or horticultural oil on the undersides of the leaves. Ladybugs and other helpers usually take care of the rest. Do not over-feed with nitrogen.A strong water jet dislodges colonies and is often enough; where needed, insecticidal soap or horticultural oil on leaf undersides is effective. Conserve ladybugs, lacewings, and parasitoid wasps, and avoid pushing growth with nitrogen. Prevention Welcome helpful bugs like ladybugs and lacewings by not spraying broadly, go easy on nitrogen, keep weeds down, and check the new growth and leaf undersides now and then so you catch them early.Scout new growth and petioles early, avoid over-fertilizing with nitrogen, conserve natural enemies, and control nearby weed hosts. Row cover used against the leafminer also excludes aphids.
Symptoms Lots of tiny round holes peppering the leaves of young plants, like buckshot, made by small dark beetles that hop away like fleas when you come near. On big plants it is mostly a looks problem, but on tiny seedlings heavy damage can stunt or kill them.Tiny round shot-holes and pits riddle the leaves, heaviest on young seedlings, giving the foliage a sandblasted look; the small dark beetles jump when disturbed. Damage is mostly cosmetic on established plants but can stunt or kill seedlings at high pressure and it disfigures leaves grown for greens. Cause Small jumping beetles called flea beetles chew the holes. They spend winter in garden debris and come out in spring, hitting tender young plants hardest in warm, dry weather. They feed on chard, beets, and spinach.Several species of small flea beetles whose adults chew the pits and holes; they overwinter in garden debris and become active in spring, with the heaviest pressure on tender new growth in warm, dry weather. Chard, beet, and spinach are all hosts. Organic treatment Keep seedlings well watered and growing fast and they will usually outgrow the damage. If beetles are swarming young plants, dust the leaves with kaolin clay or use a vegetable-labeled product, and clear out weeds nearby. Grown chard rarely needs anything.Healthy, fast-growing plants outgrow flea beetle feeding, so keep seedlings well watered and unstressed. Where pressure is high, treat with kaolin clay or a vegetable-labeled product and clear weedy hosts; mature chard seldom needs treatment. Prevention A row cover over the seedbed during the early weeks is the best protection, keeping the beetles off while the plants are small. Clean up old plant debris where the beetles spend winter.A floating row cover over the seedbed is the most reliable defense, excluding the beetles during the vulnerable seedling stage. Clean up debris where adults overwinter and keep seedlings vigorous.
Symptoms Ragged holes chewed in the leaves, especially the big lower leaves near the ground, with slimy trails that glisten in the morning. They feed at night and in damp, shady spots.Irregular ragged holes with smooth edges in the foliage, concentrated on the large lower leaves and any leaf resting on damp soil, accompanied by silvery slime trails. Feeding is nocturnal and worst in cool, wet, shaded conditions and under dense canopy. Cause Slugs and snails are soft, slimy pests that come out at night and in wet weather to chew on tender leaves. Chard's large, low leaves and the moist, shady ground under them are exactly what they like.Slugs and land snails that shelter in moist debris by day and feed on tender foliage at night; chard's broad, low leaves and the humid microclimate beneath a full stand favor them, particularly in wet weather and irrigated beds. Organic treatment Pick them off after dark by flashlight, set out shallow dishes of beer to trap them, or scatter an iron-phosphate slug bait, which is safe around pets and wildlife. Remove hiding spots like boards and dense debris near the plants.Hand-pick after dark, trap with shallow beer dishes or boards used as daytime refuges to collect under, and apply an iron-phosphate bait where pressure is high. Reduce the moist daytime harborage that sustains them. Prevention Water in the morning so the surface dries by night, give plants room for airflow, and clear leaf litter, boards, and weeds where slugs hide during the day. A ring of coarse, scratchy material around plants can slow them down.Irrigate in the morning so surfaces dry by nightfall, space plants for airflow, and clear boards, litter, and weeds that harbor slugs. Remove the lowest leaves resting on soil to cut humidity at the crown.
Diseases
Symptoms The leaves get many small round spots, about an eighth of an inch wide, with a pale tan or gray center and a darker reddish-purple or brown ring around each one. They start on the older outer leaves and spread inward, and when there are lots of them the leaves brown and die. It spoils the leaves you want to eat.Numerous small round spots about an eighth of an inch across, each with a tan to gray center and a darker reddish-purple to brown margin, appear first on the older outer leaves and spread inward; when numerous they merge and the leaf withers. Because the crop is the leaf, even moderate spotting downgrades the harvest, and severe leaf loss reduces overall yield. Cause A fungus that lives on old chard and beet debris and on related weeds, and gets splashed onto the plant by rain or overhead watering. It loves warm, humid weather and wet leaves, so it is worst in warm, wet areas and rainy spells.The fungus Cercospora beticola, which survives on infected chard and beet debris and on related weeds and is splashed onto the leaves by rain and overhead irrigation. It is favored by warm, humid weather and prolonged leaf wetness, so it is most damaging in warm, wet regions and seasons, including the long southern harvest. Organic treatment You cannot cure leaves that are already spotted, only slow it down. Pick off and throw away the worst leaves, water at the soil in the morning so the leaves dry fast, and give plants room so air moves through. In a very wet year a copper fungicide labeled for vegetables can help if you start early.There is no cure for spotted tissue; management slows spread. Remove and destroy badly infected leaves, water at the base in the morning so foliage dries quickly, and thin or space plants for airflow. In a wet season a copper-based fungicide labeled for vegetables can suppress spread if started early, but cultural control carries most of the load. Prevention Do not grow chard (or beets and spinach) in the same spot two or three years running, clean up old leaves and debris where the fungus lives, water at the base instead of overhead, and give plants room so the leaves dry quickly.Rotate chard and its relatives (beet, spinach) out of the bed for two to three years, clear and destroy crop debris, avoid overhead watering, and space and thin for airflow. Choose tolerant varieties where the disease recurs.
Symptoms Pale yellow patches show on top of the leaves, with a grayish or purplish fuzzy growth underneath in damp weather. The young leaves in the center can be twisted, thick, and curled. It is worst in cool, wet weather and mainly hurts the leaves.Pale yellow, indistinct blotches on the upper leaf surface with a grayish to purplish downy growth on the corresponding undersides in damp weather; young central leaves are often distorted, thickened, and curled. It is most damaging in cool, wet conditions and chiefly disfigures the foliage. Cause A fungus-like water mold that infects in cool, wet weather and spreads in damp air and splashing water. It survives on old plant debris and on chard's relatives beets and spinach.The water mold Peronospora farinosa (P. betae), which infects in cool, moist conditions and survives on crop debris and related goosefoot hosts, spreading in moist air and splashing water. Chard shares it with beet and spinach. Organic treatment You cannot cure infected leaves, so pick off and throw away the worst ones and help the plants dry out by giving them room. Keeping the leaves dry does most of the work; a copper fungicide is a last resort in a very wet stretch.No cure for infected tissue; remove and destroy affected leaves to reduce spread and improve airflow and drying. Cultural control is the mainstay, with copper fungicides a last resort in a persistently wet season. Prevention Water at the soil instead of overhead, give plants room so air moves through, and stay out of the bed when the leaves are wet. Move chard away from where you grew chard, beets, or spinach, and pick a tolerant variety if it keeps showing up.Water at the base, space and thin for airflow, and avoid working among wet plants. Rotate away from chard, beet, and spinach, clear crop debris, and choose tolerant varieties where it recurs.
Symptoms Seeds that never come up, or tiny seedlings that flop over and die just after sprouting, with a dark, pinched, wet-looking spot on the stem right at the soil line. You see it as bare gaps in the row. Cool, soggy soil and the slow-sprouting chard seedball make it more likely.Poor stands from seed and pre- or post-emergence collapse of seedlings with a dark, water-soaked, pinched lesion at the stem base at the soil line, worst in cold, wet, poorly drained soil where the slow chard seedball prolongs the vulnerable window. Losses show as bare gaps in the row. Cause Soil organisms attack sprouting seeds and baby seedlings, especially when the soil is cold and soggy and the seeds are slow to come up. Chard sown in cold, wet ground is at risk.Soilborne Pythium and Rhizoctonia species that attack germinating seed and young seedlings, favored by cool, wet, poorly drained soil and overwatering; old or weak seed and a crusted seedbed increase losses. Organic treatment Seedlings that have flopped will not recover. If it shows up, stop watering for a bit and let the soil surface dry out some, and clear away the fallen seedlings. There is no good home cure once it starts, so this one is mostly about prevention.Affected seedlings cannot be saved. Stop watering and let the surface dry to slow the pathogens, and clear collapsed seedlings; there is no effective home cure once it takes hold, so prevention is the lever. Prevention Wait until the soil is warm enough and not cold and soggy, keep the seedbed damp without keeping it soaking, plant at the right depth in well-drained soil, and use fresh seed. Soaking the seedballs for a day before sowing helps them come up faster.Sow into warm-enough, well-drained soil rather than cold, wet ground, keep the seedbed evenly moist without saturating it, use fresh seed, and do not sow too deep. Soaking the seedball for a day speeds emergence and shortens the risk window.
Symptoms The plants grow slowly and wilt in the heat of the day even when the soil is moist, and the leaves yellow and stay stunted. If you dig up a plant, the roots have small knots or swellings (galls) on them. It is worst in warm, sandy soils, which is why it matters most in places like Florida.Stunting, midday wilting despite adequate soil moisture, chlorosis, and reduced vigor aboveground, with characteristic root galls (knots) belowground. UF/IFAS notes chard is very susceptible. Damage is heaviest in warm, sandy soils and where host crops are grown repeatedly, so it is chiefly a southern and warm-region concern. Cause Tiny worms in the soil, too small to see, invade the roots and make the galls that block the plant from taking up water and food. They build up where chard or other host crops are grown over and over in warm soil.Root-knot nematodes (Meloidogyne species), microscopic soilborne roundworms that invade roots and induce galls that impair water and nutrient uptake; populations build under warm soil and continuous host cropping. Organic treatment There is no spray that cures an infected plant, so pull and destroy badly affected plants at the end of the season. The fix is for next time: rotate to a different bed, add lots of compost, and keep plants well watered to help them cope.No rescue for an infected plant; remove and destroy heavily galled plants. Management is preventive and cultural: build organic matter, keep plants watered to tolerate the stress, and break the host cycle for future crops. Prevention Rotate chard to a fresh spot, add plenty of organic matter, and avoid following other host crops in warm, sandy beds. In bad spots, plant in containers with fresh mix, or grow chard in the cooler months when nematodes are less active.Rotate with non-host or resistant crops, incorporate ample organic matter, avoid following susceptible hosts in warm sandy beds, and consider container culture with fresh mix or cool-season scheduling where nematodes are established.
