Food Gardening Network

Growing Good Food at Home

Dealing with Eggplant Diseases

Eggplant damaged by fungal disease

Eggplant damaged by fungal disease

Like all food crops, eggplant is susceptible to various fungal diseases. Your best weapons against these are best planting practices, which help prevent disease in the first place.

This is especially important, as there are no fungicides approved for home use for many diseases.

These best practices are aimed at producing strong, healthy plants that can withstand disease, and at avoiding situations that contribute to the development of disease. They involve keeping plants clean, dry, and undamaged.

Companion Planting: Each crop has a garden buddy that helps in some way: repelling pests, attracting pollinators, contributing nutrients to the soil. We discuss this in more detail in the article “Planting Eggplants in the Ground or in Raised Beds” of this collection. You can also review our Food Gardening Network Companion Planting Chart for a full list of good planting partners for your garden.

Crop Rotation: As tempting as it might be, it’s best not to grow the same crops in the same soil—open garden, raised bed, or container—for more than one growing season. Each plant takes certain nutrients from the soil and leaves others behind. Some crops are susceptible to soilborne diseases or pests. For these reasons, you want to rotate your crops from growing season to growing season. This will help ensure better soil health and healthier, more productive harvests. This practice applies primarily to annual crops; perennial crops can usually continue to grow where they’re planted.

Now, in a perfect gardening world, you would be able to implement a crop rotation plan that spans decades. There are some soilborne diseases that can live in the soil for up to 20 years!

Even so, it’s a good idea to switch things up from season to season. Here’s a list of vegetable crops by category. The general rule of thumb here is to plant crops from one list in the growing space of the crops in the following list in the next growing season. So, you would go from List 1 to List 2 to List 3 to List 4 and then back to List 1.

  1. Root, Solanaceous (nightshade), and Tuberous Crops
    • eggplant
    • beets
    • carrots
    • celery
    • parsnips
    • potatoes
    • sweet peppers
    • sweet potatoes
    • taro
    • tomatoes
  2. Brassicas
    • broccoli
    • Brussels sprouts
    • cauliflower
    • kale
    • kohlrabi
    • mustard
    • radishes
    • rutabaga
    • turnips
  3. Legumes and Pod Crops
    • broad beans
    • lima beans
    • okra
    • peas
    • runner beans
    • snap beans
  4. Alliums
    • bulb onions
    • garlic
    • leeks
    • oriental bunching onions
    • scallions
    • shallots
    • welsh onions

Here’s a short example of common crop rotations:
potatoes > corn > cabbage > peas > eggplant > beans > root crops > squash/potatoes > onions.

If you can’t do a complete crop rotation, consider alternating what you grow from one season to the next—a virtual crop rotation of sorts. With containers and raised beds, you have the option of changing out the soil, depending on what you want to grow there. Some container soil, especially, will be severely depleted of nutrients at the end of the growing season and should just be replaced.

Mulch: Mulch can help with water retention—but be vigilant and check for insect or fungal activity.

Watering: Water your eggplant deeply about once a week (check the soil for dryness). Do not over-water. Soggy soil invites disease. Eggplant wants about 1 inch of rain or watering every week.

Other best practices include:

  • Buy healthy, disease-free seeds from reputable sources.
  • Plant your eggplants in full sun.
  • Plant in sites with good drainage; if planting in open ground, choose a higher spot for better drainage.
  • Check plants regularly for signs of disease.

Common Eggplant diseases

Here are some of the usual culprits that might infest your eggplant plants. Remember, it’s important to remove infected plant material (leaves, roots) to prevent the spread of disease once it’s found its way onto your plant. The best way to prevent these diseases is through crop rotation every year.

Blossom End Rot

Cause: calcium deficiency

Symptoms:

  • water-soaked area on end of fruit where the flower was
  • lesion on side of fruit
  • lesion enlarges and turns brown and leathery

How it Spreads:

  • caused by a calcium deficiency in the soil

Treatment:

  • keep soil pH between 6.5 and 6.8
  • lime soil to increase calcium content
  • mulch to retain soil moisture

Prevention:

  • test soil before planting
  • water consistently
  • avoid excessive amounts of nitrogen fertilizer

Eggplant Cercospora Leaf Spot

Cause: fungus overwinters in infected plant material and can emerge at any growth stage

Symptoms:

  • sunken spots on top of old lower leaves and stems
  • leaf spots grow and can be seen on both sides of leaves with yellow halos
  • older leaf spots may become grey on top and brown on bottom
  • curled and dropped leaves
  • does not affect fruit but will stop fruit from growing

How it Spreads:

  • fungus overwinters in infected plant material
  • wind, water, insects, and birds

Treatment:

  • removed and destroy infected areas

Prevention:

  • liquid copper fungicide
  • if necessary, sulfur-based fungicide
  • plant disease-resistant varieties
  • remove plant debris
  • rotate crops annually; see crop rotation guidelines above

Colletotrichum Fruit Rot

Cause: fungus that is most prevalent in warm, humid climates or when the summer is consistently humid

Symptoms:

  • brown lesions on the fruit itself
  • lesions that have pink fungal spores called “fungal ooze”
  • dropping fruits with brown lesions

How it Spreads:

  • excessive watering
  • over-ripe fruits
  • fruits that have been weakened by pests
  • overhead watering

Treatment:

  • destroy and remove infected crops
  • fungicides after disease is present

Prevention:

  • don’t water overhead, or when fruit is ripe
  • rotate crops every year
  • destroy and do not compost infected crops

Phomopsis Fruit Rot

Cause: fungus called Phomopsis vexans that is most prevalent in warm, humid climates or when the summer is consistently humid

Symptoms:

  • pale sunken lesions on the fruit itself
  • mummified fruit in dryer regions
  • circular gray/brown lesions on stem
  • small black pimples

How it Spreads:

  • splashing rain
  • insects
  • unsterilized pruners
  • excess moisture on plants

Treatment:

  • destroy and remove infected crops
  • use fungicides after disease is present

Prevention:

  • don’t water overhead, or when fruit is ripe
  • practice three-year crop rotation
  • destroy and do not compost infected crops
  • buy disease-resistant varieties like Florida Market and Florida Beauty

Damping-off

Cause: fungi

Symptoms:

  • water-soaked, decomposing seeds
  • infected roots are gray and water-soaked
  • seedlings grow but then collapse and die
  • older plants that get infected are severely stunted

How it Spreads:

  • spores thrive in moist soil and cool temperatures

Treatment:

  • liquid copper fungicide if infection is severe
  • remove and discard infected parts

Prevention:

  • minimize soil moisture
  • plant in well-draining areas
  • avoid overhead watering; water at soil level
  • treat seeds with fungicides before planting
  • rotate crops annually; see crop rotation guidelines above

Bacterial Wilt

Bacterial wilt is one of the most devastating soil-borne diseases for many plants, but the good news is that there are many varieties of eggplant that are bred for resistance to bacterial wilt.

Cause: soil-borne bacterium named Ralstonia solanacearum

Symptoms:

  • wilting plants that are not yellow
  • wilting starting from the top
  • bacterial ooze when you cut stems

How it Spreads:

  • soil: this soil-borne disease can lie dormant in the soil for years

Treatment:

  • destroy crops
  • remove and discard infected plant matter

Prevention:

  • buy certified disease-free plants
  • rotate crops regularly
  • before planting, turn soil over and allow it to dry; repeat
  • destroy diseased plants to prevent continued contamination of soil
  • cover soil with black plastic to heat up the soil

Verticillium Wilt

Cause: fungus, which prevents the plant from absorbing water

Symptoms:

  • vascular streaking in leaves and stems
  • leaves fade, curl inward, and turn brown
  • begins at the bottom of the plant (as opposed to the top with bacterial wilt)

How it Spreads:

  • from the soil and within the root system

Treatment:

  • destroy infected plants
  • soil fumigant (by professionals)

Prevention:

  • fungicide (benomyl) can be used on roots prior to planting
  • crop rotation
  • keep area free of weeds, which carry pathogens
  • purchase disease-resistant seeds or plants

Southern Blight

Cause: fungi present in the soil

Symptoms:

  • leaves wilt and turn brown
  • fungus visible on plant stem and surrounding soil
  • discolored stem

How it Spreads:

  • fungus living in the soil
  • disease emerges in times of high temperatures, high humidity, and acidic soil
  • most frequently found in southern U.S.

Treatment:

  • remove and discard infected plant matter

Prevention:

  • buy disease-free seeds
  • avoid planting in cool, wet weather
  • avoid overhead watering; water at soil level
  • make sure plants have good air circulation and lots of sun
  • rotate crops annually; see crop rotation guidelines in this collection

Early Blight

Cause: fungi present in the soil, seeds, and transplants

Symptoms:

  • small dark spots on mature leaves closer to ground
  • target-like rings in spots
  • leaves wilt and turn brown before falling off

How it Spreads:

  • fungus living in the soil
  • wind and water splashing on plants
  • wet garden tools
  • flea beetles and other pests

Treatment:

  • remove and discard infected plant matter

Prevention:

  • liquid copper fungicide
  • disease-free seeds
  • avoid overcrowding crops
  • avoid overhead watering; water at soil level
  • make sure plants have good air circulation and lots of sun
  • rotate crops annually; see crop rotation guidelines in this collection

Phytophthora blight

Cause: fungus-like organism, Phytophthora capsici

Symptoms:

  • large, brown leaf spots
  • rotting fruit
  • crown rot
  • dieback
  • blackening of roots
  • wilting plants
  • bottom of leaves may have white spores
  • fruit may also be covered in white spores as they rot

How it Spreads:

  • over-watered soil
  • splashing of water from infected soil
  • can live in the soil for years
  • contaminated seeds

Treatment:

  • remove and discard infected plant matter
  • soil solarization

Prevention:

  • straw mulch
  • liquid copper fungicide
  • drip irrigation
  • disease-free seeds
  • rotate crops annually; see crop rotation guidelines in this collection

Which diseases have you had to treat on your eggplants? Please tell us how you prevent and handle diseases. If you spot other symptoms on your eggplants that are not mentioned here, contact your local extension center or garden center for a consult—and please let us know what you discover.

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