Axenic cultures of Pucciniastrum agrimoniae, P. boehmeriae and P. coryli.
Axenic cultures of the 3 rust fungi were established on modified Murashige and Skoog media (QMS-1 and/or QMS-5 media). For P. agrimoniae and P. coryli, good growth of colonies from urediospore-infected leaf segments took place on QMS-1 medium, containing 2,4-D (1 p.p.m.) and kinetin (0.1 p.p.m.) and on QMS-5 medium, containing NAA (1 p.p.m.) and kinetin (1 p.p.m.). For P. boehmeriae, good growth of colonies from leaf segments took place on QMS-1 medium but not on QMS-5 medium. The colonies of the 3 spp. were orange-yellow and mucilaginous and composed mainly of pseudoparenchymatous cells. The surface and underside of the colonies had plate-like or concave sori that produced urediospores. The urediospores produced in the colonies were smaller and more globular than those present on the host plants of all 3 spp. (Agrimonia japonica, Corylus sieboldianum and Begonia hiemalis, respectively). Structures which were round or polygonal and similar to peridia and ostiolar cells were produced in and around the sori and sometimes covered them.