See:
Photinia - Physiological Leaf Spot
Hawthorn (Crataegus spp.) - Leaf Spot
Cause Diplocarpon mespili, formerly Fabraea maculata (asexual: Entomosporium mespili), a fungus. The fungus overwinters in diseased leaves and shoots. Spores are disseminated by splashing water and need 9 to 12 hours of leaf wetness to infect leaves. Bright sun reduced spore survival during dry periods. Young expanding leaves are most susceptible.
Symptoms Small, dark reddish spots form; as they enlarge and grow together, the center may turn black then gray. Dark, fruiting structures (acervuli) also may be seen within spots. Defoliation can occur under severe conditions. Easily confused with physiological leaf spot.
Although this problem dominates the number of Photinia samples that have come into the OSU Plant Clinic, other leaf spotting organisms have been found including the fungus Phyllosticta sp. and the bacterium Pseudomonas sp.
Cultural control
- Space plants for good air circulation if possible.
- Remove and destroy fallen leaves.
- Take cuttings only from pathogen-free stock plants.
- Manage irrigation such that leaves do not stay wet for extended periods of time.
Chemical control Use in early spring as young shoots are developing.
- Armada 50 WDG at 3 to 9 oz/100 gal water. Do not use a silicone-based surfactant. Not for nursery or greenhouse use. Group 3 + 11 fungicide. 12-hr reentry.
- Avelyo at 3 to 5 fl oz/100 gal water. Group 3 fungicide. 12-hr reentry.
- Banner MAXX at 5 to 8 fl oz/100 gal water. Young plants may be stunted. Group 3 fungicide. 12-hr reentry.
- Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Group M5 fungicide. H
- BioAdvanced Disease Control at 0.75 fl oz/gal water. H
- Broadform at 4 to 8 fl oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
- Compass 50 WDG at 2 to 4 oz/100 gal water. Do not use organosilicate additives. Group 11 fungicide. 12-hr reentry.
- Concert at 22 to 35 fl oz/100 gal water. May cause injury to buds, blooms or tender new growth. Landscape use only. Group 3 + M5 fungicide. 12-hr reentry.
- Daconil Weather Stik at 1.38 pints/100 gal water. Group M5 fungicide. 12-hr reentry.
- Eagle 20 EW at 6 to 12 fl oz/100 gal water. Group 3 fungicide. 24-hr reentry.
- Grotto at 0.5 to 2 gal/30 to 100 gal water/A. Group M1 fungicide. 4-hr reentry.
- Heritage at 1 to 4 oz/100 gal water plus a non-silicone-based wetter sticker. Group 11 fungicide. 4-hr reentry.
- Insignia SC at 3 to 6 fl oz/100 gal water. Do not use with organosilicate-based adjuvants. Use preventively only. Group 11 fungicide. 12-hr reentry.
- Mancozeb-based products. Group M3 fungicides. 24-hr reentry.
- Fore 80 WP at 1.5 lb/100 gal water plus a spreader-sticker.
- Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker.
- Monterey Liqui-Cop at 3 Tbsp/gal water. H
- Mural at 4 to 7 oz/100 gal water. Group 7 + 11 fungicide. 12-hr reentry.
- Myclobutanil 20 EW T&O at 6 to 12 fl oz/100 gal water plus spreading agent. May observe a PGR effect. Group 3 fungicide. 24-hr reentry.
- Nu-Cop 50 DF at 1 lb/100 gal water. Group M1 fungicide. 48-hr reentry.
- Ortho MAX Garden Disease Control at 2 teaspoons/gal water. H
- Phyton 27 at 1.5 to 3 oz/10 gal water. Group M1 fungicide. 48-hr reentry.
- Propiconazole-based products. Group 3 fungicides.
- Banner MAXX at 5 to 8 fl oz/100 gal water. Young plants may be stunted. 12-hr reentry.
- Ferti lome Liquid Systemic Fungicide II at 1.5 fl oz/gal water plus another fungicide. H
- Infuse Systemic Disease Control at 2 Tbsp/gal water. H
- ProCon-Z at 5 to 8 oz/100 gal water. 24-hr reentry.
- Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens at 1 fl oz/gal water. Group 3 fungicide. H
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Group 1 + M5 fungicide. 12-hr reentry.
- Tourney EZ at 1 to 4 oz/100 gal water. Group 3 fungicide. 12-hr reentry.
Reference Baudoin, A.B.A.M. 1986. Environmental conditions required for infection of photinia leaves by Entomosporium mespili. Plant Disease 70:519-521.