September 2017. The writer (no country given) said that after a brief visit to a green he found Bulbophyllum species with leaf spots. does anyone know what might be the cause. At first there were no replies. Then in October, Ia Pestnet moderator had a look on the Internet and found that Septoria in known on orchids and is a candidate. However, the images were sent to Tony Cooke at DAF Queensland, and he suggested “fly speck”, thqt occurs on apples, and perhaps other plants.
Symptoms on apples can be seen above. An account on “fly speck” is given below:
Fly speck of apple
Flyspeck symptoms appear as small, black, shiny dots on the fruit surface.
The fungus Schizothyrium pomi.
On fruit, roughly circular groups of small black dots resembling marks made by flies on walls can be seen. The dots are superficial and easily rubbed off. It is often seen in association with smoky blotch, and is more common in organic production systems.
Source of infection and spread
Fly speck overwinters in fruiting bodies on infected apple twigs and on woody hosts in adjacent vegetation. Spores are released during cool, humid weather.
This is a late summer disease of minor importance in well-managed orchards. The disease may be a problem on fruit ripening during cool, wet weather. This can become a significant problem in organic orchards in wet seasons.
Ensure fruit are properly thinned as clusters of small fruit provide ideal conditions for disease development.
Use spray programs for black spot that include some broad-spectrum fungicide