First report of Melampsoridium hiratsukanum on common alder in Hungary

A leaf rust epidemic was observed on Alnus glutinosa at some nurseries in the south-western part of Hungary in October 2001. This rust disease of alder has been unknown in the country before.

Two Melampsoridium species were described on alders, M. alni (Thuemen) Dietel and M. hiratsukanum Ito (Gäumann, 1959). M. alni is very similar morphologically to the leaf rust of birch, M. betulinum (Pers.) Kleb. (Roll-Hansen, 1981). In contrast, M. hiratsukanum, found in Estonia in 1996 and in Finland in 1997 (Kurkela et al., 1998), is morphologically distinguishable from the two. The alder rust samples collected in Hungary were evaluated and compared directly with specimens of M. betulinum on birch. The urediniospores of the alder pathogen collected in Hungary were uniformly echinulate (Fig. 1.), 21-33 x 9-15 µm (26.24 x 11.46 µm on average), the thickness of the episporium, 1.2-1.5 µm, and the length of the ostiolar cells of the uredinia, 42 - 53 µm (Fig. 2); corresponding to the morphological descriptions of M. hiratsukanum, referred to in the literature above. The urediniospores of birch rust were smooth at their upper, rounded end, 25-34 x 10-15 µm (28.58 x 12.42 µm on average), the thickness of the episporium, 1.5-2 µm, and the ostiolar cells, 23 - 30 µm long; typical of M. betulinum.

From these comparisons, we conclude that the leaf rust disease observed for the first time on common alder in Hungary was caused by Melampsoridium hiratsukanum.