Anthracnose of pepper is caused by a complex of Colletotrichum species, including but not limited to Colletotrichum truncatum, C. acutatum, C. gloeosporioides, and more recently, Colletotrichum scovillei. The two main species associated with peppers are C. gloeosporioides and C. acutatum. C. gloeosporioides 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.

Among these, C. scovillei has reemerged in recent years as an aggressive pathogen in the southeastern United States. It is part of the C. acutatum species complex and has been distinguished by its ability to infect immature (green) pepper fruit, unlike other species that typically infect only ripe fruit. C. scovillei also has a rapid disease cycle, allowing it to spread quickly under conducive environmental conditions. Although some Colletotrichum species can be seedborne, C. scovillei has not been conclusively shown to be transmitted through seed. The primary sources of inoculum are infected transplants, crop debris, and splashing water.

Figure 1. Anthracnose lesions on Caspsicum spp.

Rui map Zheng, Bugwood.org

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Figure 1. Anthracnose lesions on Caspsicum spp.

Rui map Zheng, Bugwood.org

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Figure 2. Anthracnose lesion on Capsicum annuum.

Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

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Figure 2. Anthracnose lesion on Capsicum annuum.

Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

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The host range includes a variety of Capsicum spp., including bell, hot, and ornamental peppers. Other solanaceous crops such as tomato may also be affected by Colletotrichum species, but are not commonly infected by C. scovillei. Extensive anthracnose outbreaks have occurred on bell peppers and specialty hot peppers. Additionally, these species may cause crown and fruit rot of strawberry.

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.

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 or orange to 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.

Figure 3. Anthracnose lesion on Capsicum spp.

Rui map Zheng, bugwood.org

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Figure 3. Anthracnose lesion on Capsicum spp.

Rui map Zheng, bugwood.org

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Figure 4. Colletotrichum spp. fungal fruiting bodies within a lesion on Capsicum spp.

Cesar Calderon, Cesar Calderon Pathology Collection, USDA APHIS PPQ, bugwood.org

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Figure 4. Colletotrichum spp. fungal fruiting bodies within a lesion on Capsicum spp.

Cesar Calderon, Cesar Calderon Pathology Collection, USDA APHIS PPQ, bugwood.org

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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.

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. Because strawberry is an alternative host, this crop should be avoided as well.
• 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. Alternatives to black plastic include straw or wood chip mulch, as long as these create and adequate barrier to prevent inoculum from contactnig plant material.
• 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).

There are several fungicides labeled for use on peppers to prevent anthracnose (Table 1). Fungicide applications are recommended starting at the first fruit set and should continue as the fruit ripens.

The most effective way for organic growers to avoid anthracnose is to be diligent with preventative measures. Crop rotations, the use of mulch, frequent disease monitoring, and removal of all potential sources of inoculum are extremely important. Currently, there are no strains of peppers resistant to the pathogen and chemical options are limited. OMRI-approved copper fungicide applications may help subdue disease spread.

Copper fungicide treatments are the main option for home gardeners in preventing disease. Garden beds should be scouted frequently and infected fruits should be disposed of immediately. However, there is little action that can be taken after the appearance of disease.

• The NCSU 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

This disease factsheet was prepared by Cecelia Stokes and Ella Reeves in the Meadows Plant Pathology Lab.