Since some years, an outbreak of brown rot has been noticed in fruit trees in northeastern Japan. Apothecia of this brown rot fungus were collected, probably for the first time in Japan, by Tetsuo Kudo in 1963 from mummified cherries in an orchard in Akita Prefecture. The fungus has the following morphological characteristics: sporodochia grey; conidia hyaline or light-colored, lemon-shaped or ellipsoidal, 10-20×6-12μ, with no disjunctors; microconidia hyaline, spherical, about 3μ in diameter; apothecia Pecan Brown (Ridgway), funnel-shaped, 5-15mm in diameter, with stipes of 15-50mm in length; asci cylindric-clavate, 130-210×7.5-12μ, 8-spored; ascospores hyaline or slightly colored, ovoid to elongate-ellipsoidal, unicellular with rounded ends, 9.5-18×6.8μ.
When cherry fruits are inoculated with this fungus, there occur typical symptoms of brown rot, with abundant conidia. On potato dextrose agar media the fungus spreads rapidly, forming uniform colonies with abundant conidia. The conidia germinate readily in 0.1% dextrose solution, and hyphal anastomoses commonly occur beween developing hyphae.
The grey sporodochia, large apothecia, and abundant conidial production distinguish this fungus from both
Monilinia fructigena and
M. laxa. On the other hand, these and other characteristics of this fungus agree with those of
Monilinia fructicola (Winter) Honey, and so the authors have identified this fungus with
M. fructicola. This same species has also been isolated from plums, apricots, peaches, and pears in this area.
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