2018 Volume 2018 Issue 65 Pages 61-64
Stem base rot, wilt and blight were found on seedlings or growing plants of Glycyrrhiza uralensis cultivated for experiments in Hokkaido since 2013. Stolon pieces for propagation of the plant rotted from vascular bundles and then bore white molds on both their ends in 2017. Similar fungi were often isolated from the damaged stem base and stolon pieces. The symptoms were reproduced by inoculations with representative isolates from stem and stolon to stem bases of healthy seedlings, and similar fungi were re-isolated from the diseased seedlings. Both isolates formed colonies with white aerial mycelia and yellowish brown to brown reverse side on PDA. Their microconidiophores were straight or slightly curved, smooth, hyaline, septate, sometime blanched, elongated obclubate to cylindrical, with monophialides on the apices, 70.5 - 133.9 (- 160.1) × 2.9 - 5.5 (- 6.9) μm in size. Microconidia were hyaline, 1 or 2-celled, smooth ellipsoid to boat-shaped, 6.0 - 15.9 (- 18.9) × 2.3 - 4.9 (- 5.5) μm in size. Macroconidia were mostly 3-septate, hyaline, smooth, falcate, 25.3 - 40.9 × (3.4 -) 4.2 - 4.9 (- 5.8) μm in size. Chlamydospores were hyaline, thick walled, 1 or 2-celled, sub- spherical to ellipsoid, smooth or verrucose, 7.0 - 11.3 (- 13.3) × 5.8 - 10.4 μm in size. Both isolates were identified as members of the Fusarium solani species complex based on the morphology and rDNA-ITS sequences. We propose the name, Base and stolon rot‘ ( kabugare byo’in Japanese), for this disease new to Japan.
