Cause Many different fungi can cause leaf spots in the PNW. Phyllosticta sp. has been reported from Washington, and found by the OSU Plant Clinic. A survey in western Oregon found several fungi infecting symptomless leaves with Phomopsis sp. as the most prominent.
Symptoms Brown necrotic leaf spots, which may develop small black fruiting bodies (pycnidia) near the center.
Cultural control
- Remove and destroy infected leaves.
- Avoid overhead irrigation or apply to minimize the time leaves are wet.
Chemical control Three (3) applications, every 10 to 14 days, in spring.
- Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. H
- CuPRO 5000 at 1.5 to 2 lb/A. Group M1 fungicide. 48-hr reentry.
- Daconil Weather Stik at 1.38 pints/100 gal water. Group M5 fungicide. 12-hr reentry.
- Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker. Group M3 fungicide. 24-hr reentry.
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Group 1 + M5 fungicide. 12-hr reentry.
Reference Petrini, O., Stone, J., and Carroll, F.E. 1982. Endophytic fungi in evergreen shrubs in western Oregon: a preliminary study. Canadian Journal of Botany 60:789-796.