Anthracnose
Beginner
Scientific Name
Colletotrichum spp.
Identification
- Fruit lesions appear as small, sunken, water-soaked, circular spots
- The lesions gradually expand and darken in the centre
- The lesions develop a pattern of concentric rings and black, orange, or tan fungal structures may appear in the centre
- Lesions can form on green or ripe fruit
Often Confused With
N/A
Period of Activity
The pathogen can infect immature or mature fruit. Disease development is greatest during warm, wet weather. The longer the fruit is wet, the more severe the disease.
Scouting Notes
Latent infections can occur on immature fruit and only later develop into visible lesions. Once the fruit are infected, fungicide applications will not prevent symptoms.
Thresholds
None established.
Advanced
Scientific Name
Colletotrichum spp.
Identification
Fruit lesions appear as small, sunken, water-soaked, circular spots. The lesions gradually expand to 30 mm (1 ¼ in.) or more and develop a pattern of concentric rings. The lesions darken and small black, orange, or tan fungal structures appear in the centre. Lesions can form on green or ripe fruit of any size. Inconspicuous irregularly- shaped brown spots with dark edges may develop on stems and leaves.
Often Confused With
N/A
Biology
Anthracnose overwinters in infected plant debris but can also survive in the soil for a short time. Many common weeds and some crops are symptom-less hosts. The disease can also be seed-borne. Once leaf or fruit lesions are present, they act as inoculum for more infections.
Infection can occur from 10- 35°C (50- 95°F) with the optimum at 20- 24°C (68- 75°F). Lesion development is most rapid at 27°C (81°F). Disease development is greatest during wet weather. The longer the fruit is wet, the more severe the disease.
Period of Activity
The pathogen can infect fruit at any stage of development.
Scouting Notes
Latent infections can occur on immature fruit and only later develop into visible lesions. Once the fruit are infected, fungicide applications will not prevent symptoms.
Thresholds
None established.
Management Notes
- Plant clean seed.
- Rotate out of host crops (solanaceous crops, strawberries) for at least three years.
- Minimize leaf wetness when irrigating by using drip irrigation or overhead irrigating early in the day, so plants dry as quickly as possible.
- Some cultivars show a level of resistance to Anthracnose.
