DiseaseMedium Severity

Phomopsis Blight

Phomopsis juniperovora, Kabatina juniperi, Sclerophoma pithyophila

A fungal blight disease affecting numerous coniferous species, caused by multiple related fungi. Most severe on young trees and transplants under 4 years old, causing tip dieback, branch cankers, and progressive decline. Favored by cool, moist conditions.

Peak Season: Most active during cool, cloudy, moist weather conditions. Spore release occurs in warm, moist periods. Spring and fall conditions often favor disease development.
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Phomopsis blight showing characteristic browning and dieback in juniper

Identification & Symptoms

What to Look For

Tips of branches turn brown with progressive dieback
Small, sunken lesions on branches and stems
Trees may appear one-sided or flattened from lesion damage
Gray-black spore fruiting bodies (pycnidia) on diseased tissue
Gradual decline and eventual death in severe cases
Branch or entire tree death from girdling
Spore tendrils oozing from infected tissue in moist weather

Potential Damage

Most severe symptoms in seedlings and transplants under 4 years
Progressive dieback until entire branches are killed
Death caused by girdling of conducting tissues
Tree mortality in young plants and stressed specimens
Aesthetic damage from branch dieback and cankers
Economic losses in nurseries and young plantings

Lifecycle

Spores produced by thousands in pycnidia and acervuli on diseased twigs. Spores ooze out in tendrils during warm, moist weather. Spread by splashing water, insects, and pruning tools. Some species can enter unbroken tissue while others require wounds for entry.

Professional Treatment Approach

1

Apply preventive fungicide treatments like Fungisol during vulnerable periods

2

Improve air circulation around plants to reduce moisture

3

Avoid overhead irrigation and water splashing on foliage

4

Remove and destroy infected branches and plant material

5

Disinfect pruning tools between plants

6

Avoid mulches made from infected plant material

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against phomopsis blight.

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Mycoject Ultra

Professional-grade treatment specifically effective against phomopsis blight.

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