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Beginner

Scientific Name
Chondrostereum purpureum

Identification

• Silvering of the leaves, initially on one or two branches, eventually the entire tree.
• Symptoms can get progressively worse over the years and the trees decline and eventually die; in other cases infected limbs recover completely and exhibit no symptoms.
• Heartwood is usually stained brown and in autumn, fruiting bodies from the fungus appear on the surface of dead or severely infected limbs or the trunk.

Often Confused With

• Powdery mildew- Powdery mildew leaf symptoms occur at growing tips of the shoot as white, felt-like patches of fungal growth. Silver leaf is a silver sheen on mature leaves and usually occurs on one or two branches or the entire tree.

Period of Activity
Silver leaf disease appears after cold winters – it is an opportunistic fungi entering trees through damaged wood. Symptoms usually become apparent on apple after petal fall.

Scouting Notes
Look for symptoms during regular orchard monitoring, especially after petal fall.

Thresholds
 None established.

Advanced

Silver leaf disease is found on a wide range of deciduous trees and shrubs including apples, apricot, cherry, nectarine, peach, pear and plum.

Scientific Name
Chondrostereum purpureum

Identification
Silvering of the leaves occurs initially on one or two branches, but eventually spreads and the entire tree becomes silvery in appearance. Symptoms get progressively worse over the years and the trees decline and eventually die. In other cases infected limbs recover completely and exhibit no symptoms. Heartwood of infected trees is usually stained brown and in autumn. Fruiting bodies from the fungus appear on the surface of dead or severely infected limbs or the trunk.

Often Confused With

• Powdery mildew- Powdery mildew leaf symptoms occur at growing tips of the shoot as white, felt-like patches of fungal growth. Silver leaf is a silver sheen on mature leaves and usually occurs on one or two branches or the entire tree.

Biology
Fruiting bodies are common on the dead wood of the many tree species that silver leaf attacks. Infections occur through wounds or dead tissue.

Period of Activity
Silver leaf disease appears after cold winters – it is an opportunistic fungi entering trees through damaged wood. Symptoms usually become apparent on apple after petal fall.

Scouting Notes
Look for symptoms during regular orchard monitoring, especially after petal fall.

Thresholds
None established.

Management Notes

• Pruning cuts are susceptible to infections from spores during periods of rainy weather.
• Trees under stress are prone to infection, and winter injured tissues also provide an entrance for the fungus.
• Providing adequate drainage and fertilization helps reduce incidence of the disease.
• A strain of this fungus (Chondrostereum purpureum strain PFC2139) is registered as a bioherbicide treatment (called Chontrol Paste) to kill stumps of cut trees, but this strain does not infect apple.