Alternaria Rot
Beginner
This pest affects:
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Scientific Name
Alternaria alternata and Alternaria spp.
Identification
- Found mainly on the fruit of cherries and apricots
- Circular to oblong, initially slightly sunken lesions
- Later become firm, flattened, wrinkled and covered with olive green to black sporulation
- Rotted tissue can be readily separated from the surrounding flesh
- Most severe on overripe fruit or where rain-induced cracking or various physical injuries that expose the flesh to infection
- Can spread from infected fruit into attached healthy cherries
- Early infections on apricot appear as red rings on the fruit and can occur when the fruit is still green. As the fruit matures the centre of these rings becomes sunken and brown
Often Confused With
San Jose Scale on apricot fruit – bright reddish halo around a light-coloured centre which has a scab-like texture when the scale insect is present and a smooth texture when the scale has been removed
Peach scab on apricot fruit – lesions start as small, greenish spots and become olive-brown and velvety as they age
Bacterial spot on apricot fruit – dark brown lesions with cracking and/or pitting
Period of Activity
Pre-harvest if fruit are split due to rain.
Post-harvest and storage.
Advanced
This pest affects:
|
|
|
Scientific Name
Alternaria alternata and Alternaria spp.
Identification
- Found mainly on the fruit of cherries and apricots
- Circular to oblong, initially slightly sunken lesions
- Later become firm, flattened, wrinkled and covered with olive green to black sporulation
- Rotted tissue can be readily separated from the surrounding flesh
- Most severe on overripe fruit or where rain-induced cracking or various physical injuries that expose the flesh to infection
- Can spread from infected fruit into attached healthy cherries
- Early infections on apricot appear as red rings on the fruit and can occur when the fruit is still green. As the fruit matures the centre of these rings becomes sunken and brown
Often Confused With
San Jose Scale on apricot fruit – bright reddish halo around a light-coloured centre which has a scab-like texture when the scale insect is present and a smooth texture when the scale has been removed
Peach scab on apricot fruit – lesions start as small, greenish spots and become olive-brown and velvety as they age
Bacterial spot on apricot fruit – dark brown lesions with cracking and/or pitting
Biology
The fungus is common in orchard debris and its spores are disseminated in the air. Infection is usually associated with injury and in cherries this usually takes the form of splitting or cracking while the fruit is still on the tree. Infection may also occur through wounds created during harvest or handling. The fungus can infect sound apricot fruit via natural openings (stomates) or directly through the cuticle but these lesions are small.
Period of Activity
Pre-harvest if fruit are split due to rain.
Post-harvest and storage.
Management Notes
Cherry varieties Lapins, Summit and Sylvia are resistant to Alternaria; Bing, Sunburst and Sweetheart are susceptible.
Calcium sprays may help with reducing cherry splitting.
Handle cherries carefully during harvest and storage.
Some information included above excerpted from;
