Occurence of fungal diseases on lemon balm (Mellisa officinalis L.) and peppermint (Mentha x piperita L.) in the region of Malopolska.

This paper presents the results of the researches carried out on the subject of the diseases on herbs such as lemon balm and peppermint focusing on the health status of the plants grown in the region of Malopolska. The field and laboratory research proved that perpetrators of the diseases on the examined plants were fungi species with the numerical majority. On lemon balm septoria leaf spot (Septoria melissae) was most often observed. Moreover, fungal genera of different taxonomic groups were detected. Alternaria, Epicoccum, Fusarium, and Sclerotinia sclerotiorum occurred most often on the medicinal plant samples. The disease mint rust Puccinia menthae, has caused major problems for the peppermint growers. In the populations of fungi found on the diseased leaves the dominating were Alternaria, Epicoccum and Sphaceloma menthae. It has been stated that among all fungi isolated from lemon balm, the species Fusarium avenaceum had the highest pathogenicity to seedlings (80% of diseased seedlings). For peppermint plants the highest pathogenicity had species Epicoccum purpurascens, and caused 82% of diseased seedlings. Conducted evaluation of health status of plants showed that the lemon balm mean disease index was yearly differentiated and was the highest in 2003 (44.39). For peppermint, the highest disease index was in third year of cultivation (62.75) and was statistically higher than in previous years.

Carrot infection by Alternaria radicina in field conditions and results of laboratory tests.

Carrot black rot caused by the fungus Alternaria radicina (Meier) Drechsler et Eddy, the economically important disease of carrot (Daucus carota L.). Research was carried out in 2004 and 2005 in order to establish correlation between plant infestation in the field and laboratory experiments. To determine the incidence and severity of the disease in mature crop, a 5-degree scale was used, where 1 meant no visible disease symptoms and 5 meant total foliage infestation. Plants were rated individually and the disease index was calculated. Fungus pathogenicity in laboratory conditions was determined using a petiole assay and a root disc assay. The petiole assay was conducted during the vegetation period; basal parts of petioles detached from fully developed carrot leaves were put in contact with the growing A. radicina mycelium. The root disc assay was conducted during storage of carrot roots; root discs were inoculated with toothpicks overgrown by A. radicina mycelium. The isolate of A. radicina was pathogenic to petioles and carrot discs. Differences in the reaction of the examined cultivars in the field and laboratory experiments were revealed. However, no significant correlation between plant infestation in the field and the results of laboratory experiments were observed.