Susceptibility of Selected Juniper Cultivars to Cedar-Apple Rust, Kabatina Tip Blight, Cercospora Needle Blight and Botryosphaeria Canker

Abstract

Abstract The susceptibility of 39 juniper (Juniperus L.) cultivars to cedar-apple rust (Gymnosporangium juniperi-virginianae Schwein.), Kabatina tip blight (Kabatina juniperi R. Schneider & Arx), Cercospora needle blight (Cercospora sequoiae Ellis & Everh. var. juniperi Ellis & Everh.), and Botryosphaeria canker (Botryosphaeria stevensii Shoemaker) was studied in field plantings located in Wichita and Manhattan, KS. Cultivars of J. scopulorum Sarg. showed variable susceptibility to cedar-apple rust and most were moderately to highly susceptible to Kabatina tip blight and Cercospora needle blight. Many were also severely damaged by Botryosphaeria canker. Most J. virginiana L. cultivars were susceptible to cedar-apple rust but were more resistant to other disease problems than J. scopulorum. Cultivars of J. chinensis were highly resistant to all four diseases observed in the plantings. Conidia of B. stevensii were primarily collected in spore traps in late May and June, suggesting this is a major period for fungal infection.