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Common Vegetable Garden Problems: Cures and Controls

Curled tomato leaves may be lack of moisture, weather related, or the start of a pest or disease attack.
Curled tomato leaves
Curled tomato leaves may be lack of moisture, weather related, or the start of a pest or disease attack.

Sometimes there will be problems in the vegetable garden. There is always a cause and there is often a cure or control.

Pest problems are often easy to spot: leaves or fruit look chewed or puckered from sucking pests. Diseases can be fungal, bacterial, or viral; often symptoms may look the same–brown or yellow spots on stems, leaves, or fruits. Environmental problems often appear after inclement weather.

Be patient and take a systematic approach to diagnosing problems. Some problems will be easy and some will be difficult. Don’t be discouraged. Look also at these two articles for a photo gallery of pests and diseases: Vegetable Pest Problem Solver and Vegetable Disease Problem Solver.

Here is guide to common problems with suggestions for possible causes and possible cures and controls.

Problem Possible Cause Possible Cures and Controls
 Seedlings do not emerge after sowing.  Not enough time has passed for germination.

Temperatures are too cold.

Soil is too dry.

Soil is too wet; seeds rotted.

Birds or insects ate seeds.

Seed was too old, no longer viable.

Wait.

Wait. Plant at proper time. Replant if necessary. Place a cloche or plastic sheeting over bed to warm soil before sowing.

Water.

Replant.

Replant. Protect beds with horticultural fleece or place bird netting over beds.

Replant with fresh seed.

 Seedlings wilt and fall over. Young plants die. Dry soil.

Damping off (fungal disease).

Rotting roots or stems.

Fertilizer burn.

Cutworms.

Root maggots.

Old seed.

Keep soil evenly moist. Bottom water seedlings growing indoors.

Avoid overwatering. Sow seed in sterile seed-starting mix. Treat soil with fungicide.

Avoid overwatering; add aged compost to soil

Follow fertilizer directions. Mix fertilizer thoroughly with soil.

Check for grubs curled in soil at base of plants. Keep garden clean of debris and plant residue. Keep garden weed-free. Use cardboard collars around seedlings.

Use floating row covers to exclude flies and moths from laying eggs in soil.

Use current season seed.

 Plants wilt. Lack of moisture in soil.

Too much water; poor drainage; waterlogged soil.

Disease.

Root rot (fungal disease).

Vascular wilt (fungal disease often affecting tomato, potato, eggplant, pepper).

Root knot nematodes.

Water deeply, thoroughly. Water when soil is dry to a depth of 3 or more inches.

Stop watering; improve drainage.

Grow disease-resistant varieties. Keep garden weed free and clean.

 Do not overwater. Rotate crops.

 Grow resistant varieties. Rotate crops. Solarize soil before planting.

 Plant resistant varieties. Rotate crops. Solarize soil before planting.

 Plants are weak and spindly. Not enough light; too much shade.

Too much water.

Plants are crowded, spaced too close to each other.

Too much nitrogen.

Locate garden where there is at least 6 to 8 hours of sunlight each day. Remove cause of shade or move plants.

Stop watering. Improve drainage.

Thin to spacing recommended.

Avoid excess fertilizing.

 Plants grow slowly; leaves are light green Insufficient light; garden shaded.

Cool weather; temperatures too low.

Improve soil pH.

Too much water.

Thin plants to recommended distance. Plant where garden receives 6 to 8 hours of sunlight each day.

Protect plants with hot caps, cloches, and floating row covers.

Test soil pH. If alkaline, add soil sulfur, aluminum sufate, aged compost, peat moss.

Do not overwater. Improve drainage by adding aged compost and organic. amendments to soil. Grow crops in raised beds.

Plant growth is stunted. Leaves are pale yellow and sickly looking. Too much water. Poor drainage.

Soil nutrient deficiency.

Compacted soil and not draining.

Acid soil; pH is low.

Insects or diseases.

Yellow or wilt disease, especially if yellowing attacks one side of the plant first.

Reduce watering. Improve drainage by adding organic matter to planting beds.

Apply an even “complete” fertilizer; follow application instructions. Add aged compost to planting bed. Add aged-manure to beds in fall. Test soil for nutrient deficiency. Add trace elements.

Add 5 to 6 inches of aged compost or organic matter to soil. Turn soil to a depth of 10 to 12 inches. Improve drainage.

Test soil pH; add lime if necessary.

Identify insect of disease damage and follow recommendations form your extension service. See Problem Solver charts.

Remove affected plants; plant disease-resistant varieties.

 Leaves yellow but do not wilt. Nutrient or mineral deficiency.

Insufficient light; too much shade.

Test soil for deficiencies. Add complete fertilizer. Add aged-compost to beds at least twice a year.

Thin plants to recommended distance to reduce shading. Move garden to sunnier location.

 Leaves mottle yellow and green, mosaic pattern. Leave pucker leaves; stunted plants.  Virus disease.  Remove and destroy infected plants. Remove plant debris. Practice insect, weed control. Plant disease resistant varieties.
 Leaves and stems are spotted; darkened spots on stems and leaves. Seedlings turn brown and die. Fertilizer or chemical burn; fertilizer placed directly on plant tissue or too much fertilizer added to soil.

Disease.

Follow fertilizer instructions. Keep fertilizer off plant unless recommended. Apply at recommended rate. Mix fertilizers in soil to a depth of 3 inches or apply in bands to side of crop. Leach fertilizers from soil with water.

Identify disease and treat. Remove diseased plants. Grow disease-resistant varieties.

Brown spots on leaves. Fertilizer or chemical burn. Fertilizer placed directly on plant. Chemical placed on plant or drifted on wind to plant. Follow fertilizer or chemical application instructions. Do not use fertilizers or chemical unless recommended for use on the plant. Apply fertilizer and chemicals at recommended rate.
Leaf margins look scorched, turn brown and shrivel. Dry soil.

Salt damage.

Fertilizer burn.

Potassium deficiency.

Cold injury; low temperatures.

Water deeply, thoroughly.

Salts applied to walkways and roads in winter may splash into garden; keep salty water off foliage. Flush soil with good water. Test soil for soluble salt level.

Avoid over application of fertilizers. Flush fertilizers from soil with water. Test soil for soluble salt level.

Test soil for deficiency. Apply fertilizer rich in potassium fertilizer; add wood ash or green sand at rate of 2 to 4 pounds per 100 square feet; add aged-compost, or aged-manure.

Protect plants with floating row covers, hot caps, or cloches. Plant at recommended times.

Leaves curled, puckered, or distorted. Wilt.

Viral disease

Moisture imbalance.

Aphids.

Herbicide injury.

Remove and destroy affected plants. Rotate crops. Grow disease-resistant varieties. Be aware of diseases that attack this plant.

Control aphids which spread viruses. Remove and destroy diseased plants. Be aware of diseases that attack this plant. Plant resistant varieties.

Keep soil evenly moist; avoid over-watering. Mulch to conserve soil moisture in hot weather.

Hand destroy. Spray away with water. Use insecticidal soap.

Apply herbicides when there is no wind. Follow herbicide directions; do not apply herbicides in middle of day. Control weeds by hand.

Young leaves curl down, edges roll. Leaf surface become distorted and veins turn light color. Weed killer damage. Avoid using herbicides in garden. Hand weed.
Leaves stippled with tiny white spots. Spider mites.

Air pollution (ozone).

Spray with insecticidal soap or treat with registered miticide.

Wash foliage with water; allow to dry before night.

Powdery white coating on upper surface of leaves, stems, and flowers. Powdery mildew (fungal disease); occurs when leaves are dry but weather is humid. Plant resistant plants. Space plants widely to ensure good air circulation. Plant in full sun.
Leaves have holes; seedling and fruits chewed. Insects, slugs, birds, rodents, rabbits.

Heavy winds or hail.

Identify pest; exclude with floating row covers, bird block or fencing. Use slug bait.

Protect plants from prevailing winds with hedges or cloth barriers. Protect crops from severe weather with row covers.

Leaves shredded or stripped from plant. Rodents, deer, slugs, hail damage. Protect crops with fence, netting, for floating row covers. Use slug bait.
Blossom ends of tomatoes and peppers rot. Dry weather following a wet spell. Uneven irrigation.
Insufficient calcium in the soil.Compacted soil; water and nutrient uptake impeded.Too-deep cultivation; root injured disrupting water uptake
Mulch to even out soil moisture. Water evenly.

Add lime.

Cultivate. Add aged-compost and organic matter to beds.

Avoid cultivating too deeply.

 No fruit. Weather too cold; temperatures low.

Weather too hot.

Too much nitrogen.

No pollination.

Plants not mature enough.

Plant at proper time.

Plant so that crop comes to harvest before or after hot weather.

Follow feeding directions for variety. Avoid nitrogen-rich fertilizers. Feed soil with aged compost.

Pollinate with brush, or by shaking plant so that pollen will fall to female flowers (depending on kind). Attract pollinators to garden. Do not kill pollinating insects.

Wait.

Poor fruit yield; small fruit; poor flavor. Uneven soil moisture.

Poor soil fertility.

Improper temperature.

Mulch to retain soil moisture. Water during dry periods. Make sure watering is even and deep.

Add aged compost or aged manure to planting beds.

Plant at right time of year.

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40 Comments

    • Squash and cucumbers plants produce male flowers first, followed by female flowers. The female flowers will have tiny fruits at their base–that’s how you can tell them apart from the males. Insects pollinate the blossoms, but they must visit both the male and female flowers. If the weather is cloudy or cool or rainy, the insects may not be active. If only male flowers have appeared, wait a few days and the females will follow–and the insects can do their job of pollination. If all else fails, you can hand pollinate the female flowers: use a cotton swab to transfer pollen from the male flowers to the female flowers. Or pick a male flower, pull off the petals, and rub the pollen directly on the stigma of the female flower.

    • Yes calcium and even watering will help. You can add crushed eggs to a watering can full of water or spread the crushed eggs around the plant stem and water. Or spread a fertilizer rich in calcium around the plant. Keep the soil evenly moist so that the plant cells grow uninterrupted.

  1. My garden plants are not growing well, just not growing taller or developing well. Some tomatoes blooming, but growth very small. Pepper plants still very small. If I add organic compost or peat moss, should I do this right on top of the existing soil and just lightly turn it around the existing plants, or do I wait until this season is over and just start in the fall? I hate to waste the remainder of the season. THanks for any help!

    • You can either add the compost across the soil surface or turn it lightly under without disturbing plant roots. Irrigation or rain water will then carry the nutrients down to the feeding roots. Small fruit growth on tomatoes and peppers may be the result of cool days or cool nights as well.

  2. I have a vegetable garden as well s many flowers. Last week as I was weeding, I found a huge jelly like substance around one of my celery plants. I dug this out and thought everything was okay. Today I noticed in a windowbox with flowers, the same jelly like substance around each flower and a bunch of flies all over the plants. What is this? And more importantly, how do I get rid of it?

    • Have you added a commercial potting mix or soil to your window boxes or planting beds that contains a moisture-retentive polymer? These ploymers soak up water and then slowing release back into the soil; they have a clear jelly like appearance when hydrated.
      Another possibility is slime molds, a single-celled organism, that lives on dead plant material, often in lawns or garden beds. If you suspect slime mold, take a sample to a nearby office of the state agriculture office for identification. You can dig around slime mold organisms and remove them from the garden and dispose of them, but the spores that begin their growth may remain in the garden and form new organisms.

    • White patches on cucumber leaves is likely a sign of powdery mildew (white mold on fruits is likely southern blight or white mold). To control and kill fungal spores of powdery mildew get a fungal spray at the garden center or add a tablespoon of baking soda, 2.5 tablespoons of vegetable oil, and a teaspoon of liquid soap (not detergent) to a gallon of water and spray the plants.
      Bean leaves that shrivel: the first thing to check is soil moisture–the soil should stay evenly moist early in the season when roots have not yet grown deep; make sure your plants are getting water every couple of days. If watering is not the problem, then bacterial blight or mosaic virus may be attacking your plants–remove diseased plants and replant with disease resistant cultivars.

    • This is my first year doing a raised bed garden. We planted vegetable starts on March 16th. Nothing appears to be growing at all. Leaves are light green. Soil test showed extremely deficient in Nitrogen, Phosphorus, and Potassium. We dumped gallons and gallons of 20-20-20 on garden 4 days ago. Also, moisture tester shows moisture several days without water. Is our garden not draining properly? Redoing soil test again today for N,P,, and K. Any help would be greatly appreciated.

      • The slow growth may be linked to air or soil temperature. Seedlings demand warm temperatures to thrive; they will linger or die if temperatures are too chilly–especially at night. If temperatures remain in the 50s or 60s at night you should consider placing spun poly row covers over the plants until temperatures warm. Your moisture meter will tell you if the soil is too wet or too try. Be careful adding too much fertilizer, especially nitrogen; nitrogen can burn seedling roots. Light green leaves could indicate (1) cool air temperatures, (2) too much or too little moisture, (3) too little or too much nitrogen–that diagnosis may not be helpful but you can begin to eliminate possible cause one-by-one. Keep us posted on your progress.

    • Be sure you are not overwatering–tomatoes that have been in the garden a few weeks can be watered every three or four days. Allow the first inch of soil to dry before watering again. Pale leaves may also be an indication of pest insects feeding on the leaves; check the undersides of leaves to be sure pest insects are not harboring there.

  3. Squash plants- beautiful blossoms open, are pollinated ( I see bees inside ) and the next day fall off the plant. No fruit. any ideas? Would the male flowers just fall off the next day? I’ll try to see if they are male or female. could the plants be all males? Thank you!

    • Blossom drop can be caused by poor pollination–or no pollination. But blossom drop can also be caused by weather too hot or too cold, too much or too little water, or too much nitrogen in the soil. Blossom drop is often the result of environmental stress.

      • Good news- we worked some organic fertilizer into the soil- left for the weekend and came back to 5 or 6 growing squash. We are on the mend. Thank you for your insights- we are in CT(I should have mentioned that) and the weather has been dry, was cold and now hot etc.

  4. Im having an issue with my zucchini & Yellow squash. . . . The leaves have turned from dark green to a dusty gray color and the plants are dying. . . I dont know what to do about this!!! It seems to be spreading to other squash plants as well.
    I use an organic oil based 3 in 1 garden spray. . . The bottle says for Insecticide, fungicide, miticide. ( ingredients are Sesame oil- 5%, Other ingredients Lecithin, edible fish oil, potassium sorbate, water – 95%) I add Neem oil and a tspn of liquid soap to the spray bottle when I mix it up. . . . . . I have used this spray on all my plants, but it is Not working on these squash. . . .

    • Squash and zucchini leaves turning a dusty gray indicate (as you note) the plants are in serious decline. The spray solution may be partially to blame; if sprayed in the middle of the day the oil could exacerbate sunburn to leaf tissue. Generally, it’s best to try any spray on a few leaves before treating the entire plant. You could give the plants a compost-tea boost or feed the plants with a dilute fish emulsion drench at the base of the plants. That said, it may be too late for these plants. Plant seed or seedlings in another part of the garden; there is still enough season to get a crop.

  5. I have a garden with vegetables. My cucumbers and squash are loaded with littles. The zucchini get to about – 1/2” , the flower dries off and so does the zucchini . The yellow squash are doing the same. What is my issue?

    As for my cucumbers, they have little cukes after about 1/2” to 1” they are turning yellow and drying up. What is my issue.

    I’m in Texas! Thank you!

    • The baby squash and cucumbers are aborting. The likely cause is lack of or insufficient pollination. Early in the season this is not uncommon. Make sure you are attracting bees and other pollinators to the garden.

  6. Wonderful post and such fantastic information that you gave to us. Thank you so much for it. You made a good site and also you sharing the best information on this topic. I am impressed with your site’s blog. Thank you.

  7. Thank you for this blog! I have a couple questions. We live in the central valley California, daytime temps are around 90 to 100, evening temps 65-70.
    We have a raise bed garden and a small inground garden too.
    The small inground has two tomato plants, one is blooming ferociously and has a couple tomatoes that have matured well over the past two weeks but have ceased to continue to mature. The existing blossoms on this plant as well as the second plants bloom beautifully, begin to yellow as if they will fruit and then die and fall off. Both plants have strong structures & beautiful leaves – nearly without pest or blemish. I noticed plant number two is beginning to display some ‘curl’ on the larger leaves. Thoughts? TIA! Christine

    • The daytime temperatures are too hot; most vegetables will stop growing and be dormant until temperatures fall back into the 80s every day; the flowers fail because of the heat as well. Keep the soil just moist, shield the plants from the mid-day sun, and wait for temps to moderate–then the plants will continue to grow and set fruit.

    • I have these Mandarin trees which are drying up. Have observed that on removing the bark from the main stem just beneath the soil are all dried up from within. Please help

  8. My Zucchini Plants looking fine but I got only finger size Zucchinis. My Eggplants plants are looking good, but the fruits themelves grow just one third the size and the skins taste leathery. Too little water, too much water, too little fertilizer, too much fertilizer or what?

    • It is likely the plants are small and stressed from too little water. Keep the soil evenly moist–it should be moist 3 inches below the surface this time of year. Feed the plants a dilute solution of fish emulsion or kelp meal every 10 days.

  9. Hello there, my long squash or opa plants are well bloomed and leaves are all healthy. But opa squash fruit size is only finger size and not growing and some are half way through turning brown and burning. Donot know what to do. Please help

    • If temperatures are hotter than 87F there is not much to be done but wait for temperatures to moderate. Keep the soil evenly moist, do not let it dry out; feed the plant with a dilute solution of fish emulsion every 10 days.

    • Roots that are crowded will not mature; so be sure to thin root crops. Too much nitrogen in the soil will result in green top growth and little root maturation. Feed root crops with low nitrogen, high phosphorus fertilizer.

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