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Vegetable Disease Problem Solver

Regular visits to the garden will help you spot diseased plants before a disease spreads. Here is blossom end rot.
Regular visits to the garden will help you spot diseased plants before a disease spreads.
Regular visits to the garden will help you spot diseased plants before a disease spreads. Here is blossom end rot.

Most vegetable garden diseases can be prevented and controlled. Limit disease damage by identifying diseases quickly and taking action.

Regular visits to the garden will help you spot diseased plants before a disease spreads. Choose the most effective control and then work to prevent future disease outbreaks.

Listed here are 25 common vegetable diseases. The list is in alphabetical order.

To see diseases and pests specific to the crop you are growing, find the crop by name in the Topic Index and click through or check crops by name in the How To Grow archive.

Anthracnose

  • Anthracnose
    Anthracnose on tomato

    Description. Fungus disease. Over-winters on infected seed, plant debris, or in the soil. Wet weather promotes growth; optimum growth between 78°F and 86°F.

  • Damage. Dark brown circular sunken spot on stems, leaves, pods or fruit. Centers of lesions may ooze pink spore masses. Reddish discoloration of the leaf veins. Leaves may wither and fall. Plant may die back.
  • Susceptible plants. Beans, blackberries, cantaloupe, cucumbers, melons, mint, peppers, pumpkins, rhubarb, squash, tomatoes, watermelons.
  • Spread. Over-winters in garden in debris of diseased plants. Spread by wind, rain, animals, gardeners, tools. High humidity, high rainfall, and high temperatures encourage spread. Generally found in eastern North America.
  • Prevention and controls. Spray or dust with a fixed copper- or sulfur-based fungicide every 7 to 10 days. Remove and discard infected plants. Do not save seed infected planting area; use western-grown seed or seed from areas not infected. Rotate crops. Avoid working in the garden when it is wet which can result in spread of spores. Keep tools clean.

Asparagus Rust

  • Asparagus rust
    Asparagus rust

    Description. Fungus disease of massed reddish or black spores grows on asparagus ferns.

  • Damage. Tiny, rust-colored spores mass on asparagus ferns. Black spores mass in late summer. Fern growth is retarded. Yield is reduced. High humidity and wet weather encourage spread.
  • Susceptible plants. Asparagus.
  • Spread. Rust spores are blown by the wind or carried by gardeners, tools, animals or insects. Spores can over-winter in plant debris. Heavy dew and high humidity encourage this disease. Found throughout North America.
  • Prevention and controls. Plant resistant varieties. Cut plants to the ground at the end of each season. Remove and destroy plant debris. Keep water off of leaves. Use a preventative sulfur spray or dust every 7 to 10 days until 3 or 4 weeks before harvest.

Bacterial Blight

  • Bacterial blight bean leaf
    Bacterial blight bean leaf

    Description. Bacterial disease. Most severe where humidity is high for long periods.

  • Damage. Beans: large brown blotches bordered with yellow or red on leaves of beans. Water-soaked spots on pods. Pea stems turn purple or nearly black near the ground. Small water-soaked spots on leaves; yellow to brown spots on pods enlarge to reddish color.
  • Susceptible plants. Beans, peas.
  • Spread. Bacteria enter plants through small openings and wounds. Spread by wind, infected seeds. Over-winters in plant debris. Most severe where humidity remains high for long periods. Found throughout mid-North America, but rarely west of the Rocky Mountains.
  • Prevention and controls. Remove infected plants and discard them. Bacterial blight can not be cured. Do not save seed from infected area. Rotate crops. Avoid working in the garden when it is wet; this may result in spread of disease.

Bacterial Wilt

  • Bacterial disease
    Bacterial disease

    Description. Bacterial disease that clogs the capillaries transporting water and nutrients through plants. Common in moist soils; active where temperatures are greater than 75°F. Bacteria lives within cucumber beetles and can be transmitted to vine crops through their feces.

  • Damage. Begins with wilting of a few leaves or a small portion of the vine. Wilt spreads to whole plant within a week or so. When the vine is cut, white ooze will flow from the stem.
  • Susceptible plants. Vine crops: beans, cucumber, muskmelon, pumpkin, squash, tomato, watermelon, and corn.
  • Spread. Cucumber beetles, infected seedlings, soil, and water. Disease is most severe in central, southern, and eastern United States.
  • Prevention and controls. Remove and destroy infected plants before the disease spreads. Control cucumber beetles with rotenone or sabadilla. Wash hands and clean tools with a bleach solution.

Bean Rust

  • Bean rust on leaves
    Bean rust on leaves

    Description. Fungus disease of reddish orange to brown spore masses that cause leaves to drop.

  • Damage. Numerous, tiny, rust-colored spots appear on leaves of mature plants. Fungus may first appear as whitish raised spots on the underside of leaves. Leaves turn yellow and die. High humidity and wet weather encourage spread.
  • Susceptible plants. Beans.
  • Spread. Rust spores are blown by the wind or carried by gardeners, tools, animals or insects. Spores can over-winter in plant debris. Heavy dew and high humidity favor this disease. Found throughout North America.
  • Prevention and controls. Plant resistant varieties. Rotate crops. Remove and destroy plant debris. Keep water off of leaves. Spray or dust with a sulfur spray every 7 to 10 days until the disease is controlled.

Blackleg

  • Blackleg potato plant
    Blackleg potato plant

    Description. A fungus disease resulting in dry rot. Carried on seed and lives in the soil. Most severe in humid or rainy weather.

  • Damage. Sunken areas develop on lower stem, blacken, and girdle the stem. Gray spots and speck with black dots appear on leaves and stems. Leaf edges wilt and turn bluish or red. Plant wilts and dies.
  • Susceptible plants. Potatoes.
  • Spread. Infected seed. Spores can over-winter for 1 or 2 years in plant debris. Rain can spread spores. Tools. Black leg is found in central, southern, and eastern North America.
  • Prevention and controls. Fixed copper fungicides. Remove and destroy infected plants. Rotate crops. Clean up plant debris.

Black Rot

  • Bean rust
    Bean rust

    Description. Bacterial disease encouraged by wet weather.

  • Damage. Infects young and mature plants. Seedlings turn yellow and die. Mature plants develop wedge-shaped yellow regions and margins which expand to center of leaf. Leaves brown, die, and drop. Vascular tubes in plant turn black and foul smelling. Heads of plants may rot.
  • Susceptible plants. Broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, kohlrabi, turnips.
  • Spread. Bacteria over-winters in soil and plant debris. Rain, surface water, and insects can spread disease. Found in central, southern, and eastern United States.
  • Prevention and controls. Cannot be remedied. Remove and destroy infected plants. Clean garden in fall. Apply micronized sulfur to nearby but uninfected plants ever 7 days until harvest.

Blossom End Rot

  • Blossom End Rot
    Blossom End Rot

    Description. Environmental factors cause blossom end rot, not a pathogen. Irregular watering–water, then drought, then water, then drought–particularly when the fruit is forming is one cause. Too much water may also cause blossom end rot. A calcium imbalance in the soil may also result in insufficient water uptake.

  • Damage. Cells at the end of the blossom fail to receive sufficient water; the blossom end of fruit becomes dry, sunken, and leathery in tomatoes. Peppers can turn brown-black or light-colored and papery at the blossom end. Half of each fruit may be affected.
  • Susceptible plants. Tomatoes, peppers, watermelons, squash.
  • Prevention and controls. Maintain consistent and even soil moisture. Mulch and cultivate only shallowly during drought. The soil pH should be between 6.0 and 7.0, add limestone which contains calcium if the pH is below 6.0.

Botrytis Rot — Neck Rot

  • Neck rot onion
    Neck rot onion

    Description. Fungus disease that usually attacks onions in storage and over-winters in infected bulbs.

  • Damage. Leaves become water-soaked, gray to brown. Neck tissue of onions, garlic, and chives become brownish and soft. Dry rot occurs after harvest. Eventually, the entire bulb may rot.
  • Susceptible plants. Onions, chives, garlic, marjoram, oregano, rosemary, thyme. Sweet onions are most susceptible.
  • Spread. Fungus over-winters in plant debris. Prolonged wet weather will promote infections.
  • Prevention and controls. Keep soil healthy and rich. Remove plant debris from the garden at the end of the season. Keep plants leaves dry when watering; water at the base of the plant. Allow plants to mature completely before harvesting. Cure and store onions before storing. Do not store bulbs that have been bruised or damaged.

Clubroot

  • Clubroot
    Clubroot

    Description. A fungal disease which lives in the soil and enters a plant through its roots.

  • Damage. Roots become enlarged and swollen (clubbed) and begin to malfunction. They may crack or rot. Young plants are killed. Older plants have reduced yields. Plants yellow and wilt during the day; leaf heads are small. Plants may recover from wilt at night.
  • Susceptible plants. Broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, kohlrabi, turnips.
  • Spread. Fungal spores spread from infected plants by wind, water, or tools. Spores survive for at least 7 years.
  • Prevention and controls. Remove diseased plants from the garden. Use a 4-year rotation. Clubroot thrives in acid soil; add lime if the soil pH is below 6.0. Raise the pH to 7.2. Grow seedlings in a sterile soil mix.

Corn Smut

  • Corn smut
    Corn smut

    Description. Fungus disease causes gray-white galls on corn seedlings, stalks, and ears.

  • Damage. Whitish-gray galls appear on the ear or other part of corn plant. Galls mature, turn black, and burst releasing thousands of spores.
  • Susceptible plants. Corn
  • Spread. Fungal spores are spread by wind or transmitted by humans and tools. Warm dry weather encourages spread.
  • Prevention and controls. Plant resistant varieties. Remove and destroy galls before galls break open. Apply sulfur- or copper-based fungicide every 7 to 10 days. Remove all crop debris. Rotate crops. Do not compost diseased plants.

Curly Top

  • Curly top
    Curly top

    Description. Curly top is a viral disease. Leaves pucker, curl, and twist. Plant growth is stunted.

  • Damage. Leaves curl and yellow. Plants become stunted. Fruit does not set or yield is reduced.
  • Susceptible plants. Beans, muskmelons, pumpkins, tomatoes, watermelons.
  • Spread. Whiteflies and leafhoppers transmit the virus.
  • Prevention and controls. Curly top cannot be cured. Plant resistant varieties. Remove and destroy infected plants. Control weeds, insects, and nematodes. Cover plants with row covers if leafhoppers are a problem in the garden.

Damping Off

  • Damping off
    Damping off

    Description. Sclerotinia fungus disease lives in the soil, particularly where is high humidity and warm temperatures.

  • Damage. Base of the stem near the soil is pinched and bent over causing seedling to die.
  • Susceptible plants. Basil, beans, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, Chinese cabbage, chives, collards, kohlrabi, lettuce, marjoram, onions, savory, spinach, tomatoes.
  • Spread. Fungus lives in the soil, primarily in seed beds. Fungus can spread via transported soil or tools. Disease is present throughout North America.
  • Prevention and controls. Plant in well-drained soil. Use a sterile seed-starting mix. Water seedlings from below. Allow the soil surface to dry before nightfall. Use a fan to keep the air circulating.

Downy Mildew

  • Downy mildew on grape leaf
    Downy mildew on grape leaf

    Description. A fungal disease that thrives where nights are wet and cool and days are warm and humid. Fungus over-winters in crop and garden debris and spreads through infected seeds.

  • Damage. Yellowish to light green areas on the surface of older leaves. A felt-like, whitish growth will develop on the underside of leaves. A white, felt-like growth forms on the pods of beans, with a possible reddish discoloration around the white areas. Most common to the eastern US because high humidity and cool temperatures promote spread.
  • Susceptible plants. Beans, cauliflower, chard, cantaloupes, cucumbers, lettuce, melons, onions, pumpkins, radishes, spinach, squash, tarragon, turnips, watermelons.
  • Spread. Spores can be carried by insects, wind, rain, and tools. Spore production is greatest where temperatures are cooler than 65°F and humidity is near 100 percent. Common in the eastern United States where there are cool temperatures and high humidity.
  • Prevention and controls. Plant resistant varieties. Destroy infected plants and all crop debris. Rotate crops each year. Avoid wetting tops of plants when watering. Spray or dust with a copper-based fungicide every 7 to 10 days until harvest.

Early Blight

  • Early blight
    Early blight

    Description. Fungus disease that over-winters in plant debris.

  • Damage. Irregular dark spots appear on older leaves followed by a series of concentric dark rings. Spots usually appear on older leaves first. Defoliation can follow. Collar rot at soil level girdles the stems of tomatoes. Cankers or decay can form on fruit and tubers. Warm, wet weather can cause the disease to spread rapidly over the entire plant. Yield is reduced.
  • Susceptible plants. Celery, potatoes, tomatoes.
  • Spread. Spores over-winter in plant debris. They can be spread by wind or insects. Spread is encouraged by heavy dew, rainfall, and warm temperatures. Early blight in found throughout North America.
  • Prevention and controls. Plant healthy seed potatoes and tomato seedlings. Rotate crops. Keep garden free of plant debris. Spray or dust with copper-based fungicide every 7 to 10 days.

Fusarium Wilt

  • Fusarium
    Fusarium

    Description. Fungal disease which infects plant vascular tissues. Fungus lives in the soil and infects plants through the roots. Fungus prefers warm, dry weather with soil temperatures between 60°F and 90°F.

  • Damage. Leaves and stems turn yellow beginning from the base of the plant. Plants wilt and become stunted. Yields are reduced. Plants may die.
  • Susceptible plants. Cabbage (called fusarium yellows), celery (called yellows), melons, peas (pea wilt), potatoes, spinach, tomatoes, turnips, watermelons.
  • Spread. Spores can live in the soil for up to 20 years. Water and striped cucumber beetles can carry the disease. Fusarium wilt is common throughout the United State, particularly from the Rocky Mountain east.
  • Prevention and controls. Plant disease resistant varieties. Rotate crops. Remove and destroy infected plants. Fungicides are not effective.

Late Blight

  • Late Blight
    Late Blight

    Description. Fungus disease that attacks plants after they blossom.

  • Damage. Water-soaked round spots or patches form on leaves. Leaf spots turn brownish black; a white fungal growth may form on the underside of leaves. Leaf stalks and stems may become soft and blighted.
  • Susceptible plants. Celery, potatoes, tomatoes.
  • Spread. Fungus over-winters in plant debris. Seed, water, and wind can carry the disease. Rainy, foggy weather with temperatures between 70°F and 80°F during the day and 20 degrees cooler at night are favorable to late blight.
  • Prevention and controls. Plant resistant varieties. Plant clean seed potatoes. Rotate crops. Keep garden clean of plant debris. Spray or dust with copper-based fungicide every 7 to 10 days.

Leaf Spot

  • Leaf spot Septoria
    Leaf spot Septoria

    Description. Fungus disease that attacks leaves, also called Septoria leaf spot or Septoria blight.

  • Damage. Leaves are dotted with small spots, gray on tomatoes or tan to light brown on blackberries. Spot may have purplish borders. As spots enlarge, black dots will appear in the center. The disease may cause leaves to drop.
  • Susceptible plants. Blackberries, parsley, tomatoes.
  • Spread. Seeds, rain, wind will transmit the disease, also transmitted by working with wet plants. Occurs in central and eastern United States.
  • Prevention and controls. Plant resistant varieties. Rotate crops. Keep garden free of plant debris. Apply copper dust or liquid copper spray every 7 to 10 days.

Mosaic

  • Mosaic on tomato
    Mosaic on tomato

    Description. Mosaic, common mosaic and tobacco mosaic: viral diseases that stunts plant growth. Mosaic over-winters in perennial weeds and is transmitted by aphids and cucumber beetles.

  • Damage. Leaves become mottled yellow and green and may curl and crinkle. Plants are stunted. Yields are reduced. Infected fruit is mottled, bumpy, and misshapen and will ripen unevenly.
  • Susceptible plants. Beans, cucumbers, lettuce, melons, peppers, potatoes, raspberries, squash, tomatoes, watermelons.
  • Spread. Mosaic cannot be cured. Aphids and spotted or striped cucumber beetles can spread mosaic to susceptible plants. Mosaic over-winters in perennial weeds. The virus can also be spread by people working with infected plants. Mosaic can be found throughout North America.
  • Prevention and controls. Mosaic can not be cured. Remove and destroy diseased plants. Plant healthy seed. Plant mosaic-resistant varieties. Keep perennial weeds out of the garden. Control aphids and cucumber beetles with insecticidal soap or a light horticultural oil spray. Do not work with plants when they are wet.

Powdery Mildew

  • Powdery mildew
    Powdery mildew

    Description. Fungus disease that lives in soil and plant debris. Encouraged by low soil moisture and high humidity.

  • Damage. Gray, white, or brown velvety mold grows on surfaces of leaves and young stems. Mold spreads to whole plant. Leaves may yellow and curl then plant may wither and die.
  • Susceptible plants. Apples, blackberries, blueberries, cherries, cucumbers, melons, peas, plums, pumpkins, raspberries, sage, squash, strawberries, tarragon, watermelons.
  • Spread. Over-winters in plant debris, also in apple and plum buds. Spores are spread by water and wind. Found throughout North America.
  • Prevention and controls. Plant resistant varieties. Remove and destroy infected plants and keep garden clean of plant debris and weeds. Allow space between plants for air circulation. Rotate crops. Disinfect garden tools clean; use one part bleach to four parts water solution. Spray or dust with sulfur or copper-based fungicide every 7 days.

Root Rot

  • Root rot
    Root rot

    Description. Fungus disease that lives in the soil and affects plant vascular system.

  • Damage. Leaves yellow and lower stems wither. Plants grow unhealthy. Roots covered with mold. Plants do not respond to water and fertilizer.
  • Susceptible plants. Beans, carrots, corn, peas.
  • Spread. Fungus lives in the soil. It can be spread with infected soil and by water. Clean tools after use.
  • Prevention and controls. Remove and destroy infected plants. Plant in well-drained soil. Water less frequently but for longer periods so that water reaches deep in soil. Rotate crops. Raise beds if the soil is too wet. Control harmful nematodes with beneficial nematodes.

Scab

  • Scab on potato
    Scab on potato

    Description. Fungus disease causes scab-like growth on cucumbers, potatoes, watermelons, peaches, and other fruits.

  • Damage. Dark, sunken or water-soaked spots on vegetable leaves that result in wilt. Stems can develop cankers. Fruit develops gray, sunken spots. Potatoes develop brown, rough, irregular spots or lesions. Dark, greenish spots appear on half grown apricots and peaches.
  • Susceptible plants. Apricots, beets, cucumbers, melons, peaches, potatoes, pumpkins, squash, watermelons.
  • Spread. Scab over-winters in garden debris and soil. It is transmitted to plants by the wind. Cool, humid weather encourages spread. Scab is found throughout North America.
  • Prevention and controls. Plant resistant varieties. Rotate crops. Remove and destroy infected vegetable plants. Keep garden free of plant debris. For fruit trees, use sulfur spray or dust 2 to 3 weeks after petals drop.

Sunscald

  • Sunscald on peppers
    Sunscald on peppers

    Description. Sunscald is an environmental disorder caused by too much exposure to sun especially during hot, dry weather.

  • Damage. Large, irregular, paper-like white spots on fruit after prolonged exposure to the sun. White or reddish spots may develop on leaves. Dark molds may grow on scalded areas. Sunscald can occur when leaves drop due to unrelated disease or environmental disorders.
  • Susceptible plants. Tomatoes, peppers, apples, cherries.
  • Prevention and controls. Control diseases that cause leaves to drop exposing fruit or stems and trunks to the sun. Plant varieties resistant to diseases which can result in leaf drop. Plant varieties with heavy foliage. Fertilize and water properly.

Verticillium Wilt

  • Verticillium
    Verticillium

    Description. Fungal infection of vascular tissues causing wilting. Soil-dwelling fungus infects plants through plant roots.

  • Damage. Leaves and stems turn yellow. Plants wilt. Stems turn brown. Plant growth is stunted, and yields are reduced.
  • Susceptible plants. Apricots, blackberries, cherries, eggplants, melons, mint, okra, peaches, plums, potatoes, raspberries, rhubarb, sage, strawberries, tomatoes.
  • Spread. Verticillium wilt lives in the soil and over-winters in plant debris. It can spread during cultivation or by running water. Perennial weeds can host verticillium wilt and transmit it to crops.Fungus develops during cool, humid weather.
  • Prevention and controls. Plant resistant varieties. Practice 4-year rotation. Use a sulfur fungicide ever 7 to 10 days to control disease.

Yellows – Aster Yellows

  • Yellows on cabbage
    Yellows on cabbage

    Description. Disease caused by mycoplasmas bacteria.

  • Damage. Leaves turn yellow, then brown, then drop. Plant becomes stunted. Yields are reduced.
  • Susceptible plants. Broccoli, Brussels sprouts, cauliflower, celery, Chinese cabbage, collards, kohlrabi, lettuce, spinach.
  • Spread. Mycoplasmas over-winters in weeds and other perennial plants. Disease is spread by leafhoppers.
  • Prevention and controls. Yellows can not be cured. Remove and destroy infected plants. Keep weeds which host leafhoppers cut. Control leafhoppers with diatomaceous earth, insecticidal soap, liquid rotenone or pyrethrum, or horticultural spray oil.

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40 Comments

  1. Hello Leong, Hmmm. First, I would compare the harvest size of your cucumbers to the normal size of that variety at harvest. Perhaps, it is a large variety. If, indeed, your cucumber is the size of a bowling ball (no hyperbole) then I would suspect a couple of problems: (1) Cucumber deformities often follow poor or incomplete pollination. Parthenocarpic cucumber varieties produce only female flower and do not require pollination to produce fruit. If, however, the flowers are pollinated, distorted fruits can follow. (So check the pollination requirments of the variety you are growing.) (FYI: Gynoecious cucumber varieties also produce female flowers only, but require a separate male plant for pollination. Other cucumber varieties produce male and female flowers on the same plant, like squash, and require pollinators.) (2) Secondly, are you harvesting your cucumbers on a regular basis, picking fruits just as they reach maturity or slightly before? If you leave cucumbers on the vine too long and don’t harvest regularly, the plant will concentrate its efforts on the fruits it has–sending water and nutrients to those fruits. This can result in large fruits that are mostly water and not very cucumber tasty. Harvest your large fruits right away and see how the fruits to follow look; pick them as they approach the size you would expect of that variety. If the deformities persist, I would take a sample into the nearest master gardener help desk or the country or state cooperative extension office for an exam and opinion.

  2. I have a problem with my squash. The plants look healthy and they seem to bloom fine but almost all of the squash gets this fungus or moldy looking stuff on the bottom 1/3 or 1/2 of the fruit. It rots on the vine while the blooms and the plant look fine. Why?

  3. There are several fungal and bacterial diseases that cause the symptoms you describe. You can reduce disease attacks by keeping the foliage and fruit dry when watering and by not touching the plant when it is wet. Water close in to the base of the plant and avoid overhead watering. Keep your watering even and regular–try not to let the soil completely dry out between watering–that way the fruit will come to maturity quickly. Remove and dispose of any infected leaves or fruits. Mulch with straw under fruit or set the fruit up off the ground with a shingle or piece of wood.

  4. My first bell pepper of the year had a beautiful color but there was a whole in the bottom of the pepper and the inside had a brown spotty inside. the pepper was firm and sweet but we want to know what that is and how we can prevent it.
    Thanks mary

  5. There are a couple of possibilities–the hole in the bottom of the pepper may have been the entry point for a borer or weevil and the damage inside the fruit was simply the mess the insect left behind. Usually a borer or weevil hole will be the size of a pencil point–a simple entry or exit point. If the hole was gaping and large, it might be that the fruit cracked with inconsistent watering and a fungus or bacterial infection followed–this might leave the hole dark brown or black. For both possibilities, keep the soil evenly moist; keep the garden free of weeds and plant debris where insects might harbor–and keep your eye out for pests lounging around plants, under leaves. Pick and destroy pests. You can also check at the garden center for an insecticidal chemical or dust solution to pest problems.

  6. Roma tomatoes reach maturity in about 75 days from setting out. If you are growing tomatoes in a greenhouse with sufficient light and warmth, the tomato will not know it is winter. Check your planting calendar. If your Romas were seedlings 75 days ago, then they have reached the fruiting time of their life and are going about Nature’s business by ripening now.

  7. Thanks Stephen. The problem is that my Roma tomatoes are only tiny and so far they havent reached maturity, although they are getting there fast, Still quite a few of the tiny ones are ripening. Is there an answer to this maybe?
    thanx

  8. Yes, there is an answer to small tomatoes ripening before they reach full size: the answer is selective thinning just as you would with a fruit tree. If several tomato fruits form on one stem or branchlet you can thin away some of those fruits and allow the others to push on to full-sized maturity. You can do this by thinning blossoms early in the season, or by thinning just formed fruits at midseason, or even now, later in the season, by picking off the fast-ripening smaller fruits. This will allow the remaining fruits to use the plant’s energy to grow a bit larger and ripen. Early thinning is the best plan for the largest fruits later in the season. Your tomato plant’s genetic plan is to produce a lot of fruit and seed in order to reproduce–whether with many small fruits or fewer large fruits. Once the plant knows its fruit set it will try to push the number of fruits on board to ripening, seed production, and reproduction as quickly and as efficiently as possible. Nature’s plan.

  9. Everything I grow no matter where it’s planted grows slow and it’s fruit takes way to long to mature and are small in size, I have 3 separate above ground gardens witch are close together and I have two containers that are forty feet away. my ph in all locations runs between 6.5 and 7 . I test my soil at each location before planting using bone meal blood meal and muratic of potash to correct I had my soil tested by Texas A&M at the time I was told that I had to much phosphors and it was locking up everything, I have corrected this by replacing the soil with new and washing out some of the old, but everywhere I plant acts the same. Some plant grow fairly well while others close by just sit there all season. I have check for nematodes, not the problem. Could it be caused by viruses or bacteria? Or maybe being down wind from a oak tree farm a lot of wind where I live. I’m taking a stab at any possible cause this has been giving me problems for 4 years now. Got any ideas
    charlie

  10. You seem to have addressed your soil issues–getting an analysis from the university, correcting the problems, and closely monitoring your pH. Just to be sure you could have soil tests done each year to make sure the pH is staying balanced. Yes, soil diseases–viruses or bacterias–can cause stunted growth leading to a poor harvest. Since some plants are doing well and others are not, you might try grouping the poor performers together and see if there is a common thread–for example, are they all from the same plant family–if so you might suspect a diseases (or pests) that commonly plague that group of plants (for example, tomatoes, peppers, and potatoes can share the same diseases and pests). If that is the case, crop rotation is a start to reaching a solution (see my articles on crop rotation). Checking for plant diseases or common pests will be easier if you find that plants from the same family are not performing well; that is, you will have a list of diseases and pests to be on the lookout for. Apart from the soil and pests and diseases, there may be an environmental or physiological reason for poor plant performance: is the weather too hot or too cold for the crop you are growing–if that is the case modify your planting schedule to grow the crops in temperatures they each like best (my book will give you specific temperatures for best growing). Is your watering schedule right? Most vegetables do best with an even supply of water–avoid too dry and too wet. Is the garden site too shady or too windy (you mentioned wind). A constant breeze or wind can stress plants–all of the plant’s effort may be put into maintaining life, not flowering or setting fruit. (A vegetable garden will do best out of the wind–plant a hedge or erect wind breaks with plastic sheeting or horticulture cloth.) Perhaps the best place to start is by listing each crop and its plant family and then charting how it performs–a few months of close observation and record keeping may help you solve the problem and give you a blueprint for all of your future gardens. Keep me posted–I am certain you will find the solution in due course.

  11. My chilli pepper and bell pepper plants have got brown/black areas at stem junctions – with some plants I now see brown streaks developing on the stems. I also have what might be same problem with broad bean plants – but this starts with leaves blackening and then stem streaking. Any advice very welcome – thank you.
    Kit

  12. My cucumbers, squash and tomatoes are all flowering beautifully but produce no fruit. I’m not sure if the blossoms are falling off or are being eaten. What would cause this? Thanks. Helen

  13. For the last 2 seasons my tomato plants have been getting black spots that start by covering the leaves closest to the ground and work their way up the plant. Eventually the leaves turn yellow and then brown. It starts off when the plants are young and first planted and continues through the season. This year I have been very diligent about clipping the yellowing leaves off. I’m not sure if this is because my compost isn’t decomposing enough before I put it in the garden or it’s a different sort of problem. Any suggestions?

  14. Chili pepper and broad bean problems: First, chili peppers are susceptible to both bacterial and fungal diseases that can cause brown/black spots on stems and leaves. These diseases affect the vascular system of the plant and once detected it is likely already too late to save the plant. The particular disease you describe may be a bacterial canker–if in removing the plant you found a brown-red ooze in the stem, bacterial canker is likely. Bacterial and fungal diseases often visit plants of the same family and can live on from season to season in the soil or garden debris–so controlling an outbreak is an important step in protecting future crops. Here are important controls to protect future crops: keep the garden weed and debris free–clean up after every season; rotate crops of the same family (peppers are members of the tomato family) to new beds each season; clean the infected soil–place plastic over the growing bed and solarize the bed for two months or more; use certified disease free seed and seedlings–do not save seed from infected plants or from crops in the affected part of the garden. And always avoid overhead watering; irrigate at the base of all vegetable crops. As for the broad beans, again, it sounds like a fungal disease–perhaps anthracnose (which can infect beans, peppers, tomatoes). Anthracnose usually attacks leaves first. Remove infected plant parts or plants; spray or dust with sulfur to prevent spread, and again–keep the garden clean (bacteria and fungi overwinter in gardens), choose resistant plants or seed, and rotate your crops next season.

  15. Flowers and no fruit: there are a couple of potential causes. First, and easily fixed, is poor pollination. Flowers form but if pollination does not follow neither will fruit. In the case of tomatoes–a complete flower with male and female parts in the same flower–you can give your plant a gentle shake to help the pollen fall to the female part of the flower. Cucumber and squash have separate male and female flowers; the male flowers blossom first followed by the female flowers; if the weather is cloudy and pollinators are not active to bring pollen from the male to the female flower–you may need to hand pollinate cucumbers and squashes by introducing the male flower to the female flower and giving them both a little shake or use a cotton swab to transfer pollen from the male to the female. There are other potential causes of flowers and no fruit–these are sometimes lumped under the term blossom drop. There are a few potential causes of blossom drop: temperature extremes–when the night temperature falls below 60F or when the nighttime temperature is higher than 70F or daytime temperatures higher than 85F pollination will not occur; the solution–wait for the weather to change. Too much nitrogen in the soil can cause blossom drop as well; be careful to not overfertilize your garden beds–it’s best to use aged compost to feed the garden–aged compost will be balanced in its nutrients. Too much or too little water can also stress plants and cause blossom drop–keep your soil evenly moist. Finally, the tarnished plant bug will feed on tomato family plants and can cause blossom drop; keep the garden clean of weeds and debris to lessen the bug population or exclude bugs from crops with floating row covers.

  16. Older tomato leaves spotting then yellowing and eventually the entire plant is affected: these are descriptions of bacterial or fungal diseases at work. Leaf spots and wilts can be caused by bacteria that clog the plant’s water-conducting vascular system and attack and kill plant cells. Bacterial cells can be spread around the garden by splashing water, insects, animals–including humans, and tools–moving from one diseased plant to the next. Once in the garden bacterial diseases are very difficult to control; remove and dispose of infected plants–send them out with the household trash, don’t put them in the compost pile where they can live on if not fully decomposed. Clean tools with a 10 percent bleach solution. Some but not total control may come with copper compounds. Fungal diseases that display similar symptoms in attacking tomato plants are early and late blight, Fusarium wilt and Verticillium wilt. Fungal diseases are not uncommon in the vegetable garden or the tomato patch. Fungi attack and detroy plant roots and then spread to the plant’s vascular system–blocking the flow of water to stems and leaves. Keeping the garden clean of plant debris is one way to make sure fungi don’t stay in the garden indefinitely. Crop rotation is important–you have had the same problem for two seasons–so rotate tomato family crops to another part of the garden and don’t plant them again in the same spot for at least four years–this will reduce the buildup of fungi. Always water your vegetable crops at the base of the plant–cut out all overhead watering or splashing water that can spread fungi. Mulch to keep splashing water down. Plant disease resistant or tolerant varieties going forward; use certified disease-free seed. A bit of work, but you will get ahead of these diseases in time.

  17. Regarding bell peppers: damage at the base of the peppers is appearing. A red spot with a damaged section sometimes on both sides but no hole. The rest of the fruit is quite wholesome but this is affecting the quality of the fruit. Is this bottom end rot?

  18. Perhaps this is blossom-end rot–a small water-soaked area at the blossom end of the fruit; the tissues dry and shrink and may become flat or sunken. It’s best to remove affected fruits so that the plant can put its energy into healthy fruits. Plant peppers in low raised beds covered with plastic mulch to ensure the soil if sufficiently warm. Make sure your soil is loose and well amended with aged compost. Maintain even soil moisture throughout the growing season. Avoid nitrogen-rich fertilizers. Adding bone meal and blood meal to the planting bed will offer your plants a slow, organic fertilizer rich in calcium and magnesium. As well, choose varieties that are resistant to blossom-end rot. Blossom-end rot develops when there is too little calcium in young fruits. Calcium comes from the soil dissolved in water. Making sure there is calcium in the soil and that plants are evenly watered can solve the blossom-end rot problem.

  19. Can anyone tell me why my red leaf lettuce is so red it is almost purple, my tomato, brussels sprout, brocolli, hosta, euonymous, and tulip leaves are all turning bright purple? They are all in diffrent gardens; all look wonderful but some of the tomato plants look very ill and are yellowing and drooping? I fertilize with very well composted horse manure from my own animals and have for nearly 20 years. I am just about to take a soil test, but it only checks for the 4 major home test problems and I would love to hear from fellow gardeners.
    Thank you kindly,
    Kim

  20. Lack of phosphorus in the soil can result in red to purple color changes in leaves. The top of older leaves can become dark green and the undersides turn red to bronze. Purple to reddish color may show in leaf veins and stems–particularly on younger plants. A soil test should tell you if this is the case. If so, soil applications of phosphorous-containing fertilizers would be in order. Use a complete fertilizer, bone meal, or rock or colloidal phosphate. Mix these into the top 6 to 8 inches of soil so that it gets to the roots quickly. Certain herbicides can cause red to purple color change in leaves, also; but this is usually accompanied by leaf distortion and then die back along the leaf margins.

  21. Peppers demand patience and very warm soil and air temperatures and the right nutrients to produce fruit. Since your peppers are growing large–warmth is probably not a problem. Give your peppers successive feedings throughout the growing season–a feed rich in phosphorous to encourage fruiting is in order. Aged compost with a dusting of kelp meal should work to start. Apply two pounds per square foot about three weeks after transplanting starts into the garden. Three weeks later apply an equal mix of compost and bonemeal and Epsom salts (rich in magnesium for development) at the same rate. In another three weeks side-dress the plants with aged compost. Make sure your plants get an inch of water each week–slow soak the soil to a depth of 4 to 5 inches.

  22. My zucchini stems are split and growing deformed tumor like spiky growths, the green beans next to them are wilting and the stems are deforming, the carrots next to that are deforming underground also, they appear
    to be turning inside out. Last year I had cabbage and Brussels sprouts in that area and they were deforming before I pulled them out thinking it was club root. It seems to be contained to one area of the garden, the rest of the row and hills are normal. I thought it was insects and treated with 7, took soil samples to the UW extension, and added topsoil and compost this year with no results. Any ideas?

  23. My zucchini plants are producing fruit, but the stems “crack” open at several places and the insides of the stem are exposed. The plants continue to grow and sometimes send out new stems. Eventually the plant dies. Is this a bacterial/viral problem, nutrient problem or weather/insect related? It has been extremely hot, humid and rainy here in Minnesota.
    Another problem, the “red” pepper plants that I purchase never produce red peppers – just green. I leave them on the plant as long as possible but finally have to pick them because they are large or to save them from the animals.

  24. Cracking squash and zucchini stems in hot, humid, and rainy weather is likely environmental. In these conditions it is difficult to keep your plants evenly moist and growing evenly. The soil becomes wet, then dries, then wet again; the plants grow in fits and starts–quickly, slowly, quickly taking up moisture and nutrients unevenly–and stems crack. Once stems crack, it is easy for bacterial and viral diseases to enter the plant’s capillary system and for disease to spread–eventually causing the plant to die. An organic mulch or plastic sheeting across the growing bed may shield plant roots from too much moisture and help to keep the beds evenly moist. Once stems crack, harvest your squash before disease can spread; smaller zucchini will be more tender and tasty than larger ones.
    Red color comes to red peppers in time; when the plant reaches maturity and ripeness. But red peppers do not have to achieve redness to be picked and brought to the kitchen. As long as the your day and night temperatures remain above 65F, your peppers should continue to mature and ripen. Keep a notebook with the expected days to maturity for each crop so you have a solid idea how your crops are maturing. To protect crops from animals drape bird netting across the plants or across frames set over plants–this will exclude larger animals and birds.

  25. Deformed vegetable fruits and roots: one would suspect a soil-borne disease or organism. Send a sample of one of the deformed fruits or roots off to the extension and see if a plant pathologist can give you a definitive answer. Rotate your crops out of this section of the garden for four years; don’t plant there. You may want to place a clear plastic sheeting over the planting bed during the warm season to solarize the soil; this will likely kill both bad and good organisms in your soil. If you can not allow this part of the garden to rest and restore for several years, then plant in newly established raised beds. Make sure your soil is well-draining and rich in aged compost and organic matter.

  26. I discovered a bright pink fungus-like clusters growing in my parsley plant, on the soil around the stem. The parsley seems fine – so far – any idea what this is? cause? problem? Thanks.

    • The fungus you see may be Microdochium patch — a pink fungus that can grow where there is organic debris. Clean organic material from under the plants. Look for an organic fungicide at the garden centers and spray the pink patches. Often horticultural oil will suffocate fungal spores.

  27. Hello! I just found some very small purple dots covering one of the leaves of a small green bell pepper plant I have (at least I think it’s a bell pepper;they did get mixed up somehow). Otherwise it looks pretty healthy, and I didn’t know if that could be caused by a disease or if it is even a cause for concern. I also found a couple similar pin-size purple dots on another bell pepper plant, though its coverage of the leaf wasn’t as thorough. I’m growing here in South Dakota in pretty bare soil and lots of sun and watering with occasional organic fertilization. Any advice you have would be appreciated, thanks!

    • The purple dots on pepper leaves could be insect eggs (if that’s the case you can crush them with your thumb) or they could be the start of a fungal disease called bacterial leaf spot. If leaf spot is the culprit, the spots will turn from purple to black in time. Leaf spot can appear as slightly raised spots on the undersides of leaves; they usually darken and take on a greasy appearance. This disease can spread quickly through the garden. Clip off the leaves that are infected and put them in the trash. Spray the plants with compost tea (a natural fungicide) or with a copper-based fungicide. If the disease continues to spread you will need to remove the plants from the garden and dispose of them in the trash. Next year make sure you get disease resistant seed.

  28. My banana pepper plants are growing great but once my pepper gets to be mid sized, they get this brown mushy spot about half way down the pepper. It happens almost overnight. Tlive had to pick and toss 5 peppers over the last 2 days and another one got it today. The spot also seems to grow in size fairly rapidly.

    • Periods of dry soil followed by excess water can cause this; also lack of calcium. Avoid wetting the foliage and fruit; water at the base of the plant. Feed the plant with an all-purpose fertilizer with calcium and magnesium added such as Lily Miller Mor-Crop.

    • Check soil moisture to be sure it is moist at 2 to 3 inches below the surface. Check to see if plants may have been hit by herbicide drift from nearby spraying. Be sure excess fertilizer was not applied. Feed the plants a dilute solution of fish emulsion every 10 days.

  29. My garden was beautiful then a few leaves on my cucumbers got brown spots and started to turn yellow and wilt and dry up and very quickly all the cucumbers plants were dying. Then my tomato leaves started with brown spots on the lower portion of plant then turned yellow the lower stems started wilting and then leaves became brown and brittle, then the leaves on my melon vibes started with brown spots leaves started to yellow then wilt and get very dry looking and die. Something is spreading and killing my garden. I wish I could post some pictures. I am devastated after putting in so many hours tilling, planting and weeding.

    • The plants are likely infected with a fungal or bacterial disease. Fungal diseases can be slowed by applying a fungicide to the foliage of plants; do this immediately; treat both healthy and unhealthy plants. Water at the base of plants, not overhead. If plants decline rapidly, you may want to remove the most diseased to slow the progression to other plants. If stems turn brown or black and begin to ooze, then the disease is bacterial and all infected plants should be removed right away. Bacterial diseases can sometimes be traced to poor soil fertility or drainage; add aged compost or organic planting mix to the soil.

  30. Moved to Florida early this year, about an hour north of Tampa and not near the beach. Because we’re mostly on sugar sand, We built raised beds. Brought in tree compost/dirt from the local tree trimming company to fill them. Everything started off wonderfully. Tomatoes grew to 5′ tall, Peppers to 2′, Squash huge. Dark green and healthy looking. But then the corn didn’t get more than 2′ tall and died off before the ears developed, tomato leaves started turning yellow from the bottom up. I got a few large zucchini then the plants suddenly almost overnight died followed by the summer squash. At the same time I got deluged by bugs, stink, leaf legged, citron, cucumber and cucumber worms and several others I haven’t been able to identify. I sprayed with an insecticidal soap that didn’t seem to have any effect. I ordered “Army Nematodes” that never came. Was trying to keep it organic and pretty much chemical free. Guess that was a mistake. None of it ever fruited normal size, Everything was small except the first zucchini. Now the pepper leaves are getting covered in tiny brown spots. I’ve fertilized with nitrogen (the guy I got the compost/dirt from recommended this) and standard vegetable fertilizer. I did make the mistake of watering with a sprinkler overhead as the garden is a long way from the well and there was no way to run soaker or drip systems in a short time. I won’t make that mistake again. I trimmed back all the bad leaves and branches on the tomatoes and bought some sulfur fungus killer and some Seven (uck) for the bugs yesterday but am hesitating to use them. Any advice would be appreciated.

    • Every year we learn something new from the garden. It will take a bit of detective work to figure out what went wrong. Was there environmentally stress–temperatures consistently greater than 87F? If so, replant as temperatures moderate. Could the soil ingredients added to the raised beds have been tainted? Was watering even throughout the growing season–could the soil have gone dry; adding commercial organic planting mix or aged compost can help the soil retain moisture around roots. Overhead watering wets foliage but may not bring enough moisture to roots. Since you have a long growing season; you may want to replant; perhaps introduce a different soil, drip or soaker hose or hand irrigation. Keep a garden log may help you discover what might have gone wrong.

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