Anthracnose of Pepper

Pathogen

Anthracnose is caused by a group of fungi within the genus Colletotrichum. The two main species associated with peppers are C. gloesporiodes and C. acutatum, but there are several species that may cause this disease. C. gloesporiodes is more likely to infect mature fruit, whereas C. acutatum is more likely to infect immature fruit. Many species of Colletotrichum infect more than one host and more than one species may infect a single host.

Host Crops

Anthracnose is known to infect a wide range of commercial pepper plants and related solanaceous crops. Extensive outbreaks have occurred on bell peppers and specialty hot peppers.

Host Parts Affected

All above-ground parts of the plant are susceptible to infection, but the fruits are most impacted by this disease. Ripe and over-ripe fruit tend to be more susceptible, but pepper plants can become infected at any growth stage, as well as at post-harvest.

Identification

Fruit lesions are the most common symptom. Initially, the lesions are small, depressed, and circular. As the disease progresses, they become much larger and develop mats of salmon to pink-colored spores, causing their surface to appear wet and gelatinous. The centers of the lesions can range from tan, orange, brown, or black. The colored spore mats seen on the fruit features are characteristic of this disease. Concentric circles commonly surround the lesions. Eventually, the entire fruit will rot. Anthracnose can cause a latent infection where contaminated, immature fruits may not show symptoms of disease until fully mature.

Favorable Environmental Conditions

The pathogen prefers temperatures of around 80⁰F (27⁰C) and high levels of precipitation. The pathogen survives inside or on the surface of seeds. It can also over-winter in soil in the form of microsclerotia, which are very small, compact masses of hardened mycelium containing nutrient reserves for extreme conditions. Rain splash carries fungal spores from infected soil, plant debris, and/or fruits onto nearby plants. Excess rain can lead to higher rates of infection and crop loss.

General Disease Management

Management of this disease requires an integrated approach that includes preventative practices and control measures. Implementing the following techniques can help prevent losses due to anthracnose:

Use pathogen-free seeds. Select seed sources that are certified or known to be pathogen-free to prevent disease introduction.
Rotate crops. Crops should be rotated to non-solanaceous plants for 2-3 years.
Do not use overhead irrigation. Irrigation systems that limit water splash should be incorporated. Additionally, limiting field operations when plants are wet will help reduce spread.
Control weeds and solanaceous volunteers. Regular weeding should be performed near transplants along with the removal of solanaceous volunteers.
Destruction of crop residue. After harvesting fruit, fields should be immediately mowed. All plant debris should be worked back into soil to encourage complete break-down of infected material.
Scout fields. Frequently monitor fields for signs of disease and remove infected fruit immediately.
Use black plastic or other material. Creating a barrier between the pathogen in the soil and the plants will minimize disease.
Adequate drainage in the fields. Good drainage is necessary to reduce extra moisture and water-logging of crops.
Use of fungicides. Fungicides are most effective when applied preventatively (before disease occurs).

Useful Resources

The NC State University Plant Disease and Insect Clinic provides diagnostics and control recommendations
The NC State Extension Plant Pathology portal provides information on crop disease management
The Southeastern US Vegetable Crop Handbook provides information on vegetable disease management