DiseaseMedium Severity

Hawthorn Leaf Spot

Entomosporium mespili

A fungal leaf spot disease affecting hawthorns and photinias during cool, wet weather. The disease causes distinctive bright red spots that can merge into large maroon blotches, leading to early defoliation.

Peak Season: Most active during cool, wet weather (60-80°F with 12-24 hour leaf wetness). May continue year-round in mild winter climates on evergreen hosts.
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Hawthorn leaf spot showing characteristic dark spots and leaf damage

Identification & Symptoms

What to Look For

Small, circular, bright red spots on leaves during cool wet weather
Many small spots growing together to form large maroon blotches
Early and heavy defoliation on severely infected plants
Reduced landscape screening value
Increased sensitivity to cold injury and other stresses
Lesions on young green twigs in some cases

Potential Damage

Severe defoliation reducing plant aesthetic value
Weakened plants more susceptible to cold injury
Increased vulnerability to other diseases and insects
Loss of landscape screening function
Reduced plant vigor from repeated infections

Lifecycle

Fungus persists through winter in lesions on young twigs or in acervuli on fallen leaves. Primary infection begins when spores splash onto new leaves in spring. Many secondary cycles follow, with new generations of conidia causing successive lesions throughout the growing season.

Professional Treatment Approach

1

Apply Fungisol preventively before wet weather periods

2

Improve air circulation through proper spacing and pruning

3

Avoid overhead watering to reduce leaf wetness

4

Remove and destroy fallen infected leaves

5

Plant resistant varieties where available

6

Apply treatments early in disease cycle for best results

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against hawthorn leaf spot.

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Arborfos

Professional-grade treatment specifically effective against hawthorn leaf spot.

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