Strawberry

Anthracnose of Strawberry

Colletotrichum spp.

Fungus

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In a Nutshell

  • Light brown, water-soaked spots on ripening fruit.
  • Dark brown or black round, sunken injuries on ripe fruit.
  • Discolored plant tissue, mainly above the roots.
  • Black spots and damages on leaves.
  • Dark brown or black sunken, circular spots on all green parts.

Can also be found in

1 Crops
Strawberry

Strawberry

Symptoms

All parts of the plant can be affected by this disease that causes rot. The most obvious symptoms are rotting fruit and discolored tissue near and above the roots, also called ‘crown rot’. When the crown of the plant is infected, the whole plant may wilt. You can see discoloration by cutting open the crown of the infected plant. Fruit rot starts as light brown, water-soaked spots on ripening fruit, which turn into dark brown or black, hard injuries. Under humid conditions, orange-colored liquid may come out of the fruit injuries. Black injuries on buds and flowers and dried out flowers are an early sign of infection. Leaves may also have black spots and damages, but this alone does not mean the plant has anthracnose.

Recommendations

Organic Control

Look for products that explicitly say they control the disease. These are made from helpful bacteria or fungi. These products work best when used before the disease starts. Keep your soil healthy by maintaining and/or adding organic matter and removing plants debris from the previous year. A healthy soil may have many helpful organisms that stop soil-borne pathogens from spreading.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. It's very important to spray when the plants are at the stage of blooming. Do not wait until you see symptoms on the fruit before applying a treatment. Only use fungicides that are approved by the government. Change the type of fungicide you use to stop anthracnose from becoming resistant to the most effective fungicides. Read the label of the fungicides you choose and make sure you understand how they work, and follow the instructions and rules for using them. Some fungicide labels may also say that they can be used for dip applications at transplanting phase, which can provide further protection to your crop.

What caused it?

Anthracnose is a fungal disease and one of the most damaging disease for strawberries. It can cause big losses throughout the growing season and after harvesting. The disease usually enters the fields through new strawberry transplants. The pathogen may be there but not show any signs until the temperature and humidity is good for it to grow. The disease grows best when there is warm and humid weather. When rain drops hit the ground, they can push soil particles into the air and spread the disease. This is especially true if it is windy. It has also been reported that the pathogen can survive in the soil and plant debris for up to nine months and can infect weeds growing near the field. Even the movement of machines and people through the field can spread the disease.

Preventive Measures

  • Use healthy transplants and make sure to follow up with good cultural practices as it is sometimes hard to know if your transplants are really disease-free.
  • Use cultural practices that make sure the air can circulate around the crop and that the fruit dries quickly, both in the nursery and in the field.
  • Cover exposed soil with straw mulch to stop the disease from spreading through water droplets.
  • Avoid plastic mulches which favor the spread of the disease.
  • Use bottom watering or drip irrigation instead of overhead watering.
  • Apply fungicides, either conventional or organic, that work against anthracnose when the plants are blooming and if the weather conditions are favorable for the disease.
  • These fungicides are used to keep the disease from building up, even if you don't see any symptoms.
  • Plant in soil that is free of old plant debris and make sure the soil is healthy by adding new organic matter.
  • To make sure the soil is completely free of the disease, you can use methods like soil fumigation or heating the soil with the sun (solarization).
  • Keep the field free of weeds on a regular basis.

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