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Anthracnose fruit rot of strawberry

Quick facts

  • Anthracnose fruit rot is a fungal disease that causes fruit rot and flower blight in warm, wet weather.
  • To manage this disease, buy hardy, disease-free plants, use mulch and drip irrigation and keep your patch clean.
  • There aren’t any varieties resistant to anthracnose that are hardy in Minnesota.
Fruit rot progression

How to identify anthracnose fruit rot

Fruit symptoms

  • Pink and red fruit develop light-brown spots or blotches that eventually turn darker brown and sunken.
  • Rotted areas of the fruit remain firm and dry.
  • Pale orange to salmon colored, spore masses cover the lesion during warm, humid weather.
  • Eventually, the fruit dries, shrivels and turns hard and black.
Infected fruit

Flower symptoms

  • Blossoms can be infected at any stage of development.
  • Infected blossoms quickly die, dry out and turn brown.
  • The brown discoloration often extends down the flower stalk.

How does anthracnose fruit rot survive and spread?

  • Anthracnose fruit rot is most commonly caused by the fungus, Colletotrichum acutatum and rarely by C. fragariae and C. gloeosporioides).
  • It is usually brought to a site on infected plants.
  • The fungus overwinters on infected plants, plant debris and dried out fruit.
  • Spores are produced in a sticky mass during wet weather above 68 F.
  • Anthracnose spores are spread by:
    • Water, through splashing or wind-driven rain.
    • People or equipment moving through the field.
  • Spores don’t become airborne so they don’t spread over long distances in the wind.
  • The fungus has the ability to attack all plant parts, but fully open flowers and ripening fruit are most likely to be infected.
  • Under warm, wet conditions, the fungus produces spores on any infected plant part which spread and infect nearby plants.

How to manage anthracnose fruit rot

Buy hardy, disease-free plants

  • There are no varieties resistant to anthracnose fruit rot that are hardy in Minnesota.
  • Purchase plants from a supplier with a good reputation.
  • Inspect all plants for symptoms of disease.
  • Plant only healthy, symptom free plants.

Use mulch, drip irrigation and good sanitation

To reduce the chance spores will be splashed between plants:

  • Maintain one to two inches of straw mulch between the rows or on walking alleys.
  • Avoid the use of overhead irrigation and use drip irrigation or a soaker hose. If overhead irrigation can’t be avoided, water early in the morning on a sunny day so leaves dry quickly.
  • Remove infected berries from the strawberry patch and bury them in a compost pile. This reduces the spread of the disease to developing fruit.

Fungicides

  • If anthracnose has been a problem in the past and weather is warm and wet during flowering and fruit production, fungicides can be applied to reduce infection.
  • Anthracnose is not easily controlled by fungicides. You should expect less disease but not complete control.
  • Fungicides with Copper, Captan or Bacillus subtilis listed as the active ingredient provide some protection from anthracnose fruit rot.
  • All label instructions must be read and followed when applying a pesticide.

Use Fungicides Safely

The name of the plant being treated MUST BE LISTED on the fungicide label or the product cannot be used! Some products are registered for use on ornamental plants but are not safe to use on strawberries that will be eaten. Always completely read and follow all instructions on the fungicide label.

CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

Michelle Grabowski and Karl Foord, Extension educators

Reviewed in 2019

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