Preliminary Investigations about the Mode of Transmission and Spread of Xanthomonas campestris pv. graminis on Forage Grasses

Abstract

Extensive studies showed that no disease was caused when seeds of different forage grasses were inoculated with Xanthomonas campestris pv. graminis. The disease could easily be induced by infecting the plants in the root system, leaves or flower. The inoculation site in the leaf proved to be of vital importance for the development of the disease. Wilting symptoms were quickly induced when the pathogen was inoculated near the leaf base. Plants in root‐contact with diseased plants showed disease symptoms. It is not known whether these symptoms were caused by the bacteria or by toxins released by nearby diseased plants. Cross inoculation trials on different grass varieties revealed that different pathovars exist in the group of xanthomonads, pathogenic to forage grasses. Some have a broad host range whereas others are more limited to a single plant genus. Field trials suggest that in Belgian climatic conditions, the losses caused by bacterial wilt are rather limited.

Epidemiological aspects of bacterial wilt of fodder grasses1

“…Cutting height has an influence on disease development (Leyns et al, 1988). Many observations have shown that the lower the inoculating instrument cuts the plants, the faster and heavier will the disease occur.…”

Effect of Plant Age and Humidity on Development of Bacterial Wilt of Forage Grasses

“…This indicates that old plants may be more tolerant to disease than young ones. Leyns et al (1988) reported that X.c.graiiriizis was easily isolated from flowering stalks and that wilt symptoms were quickly induced when the pathogen was inoculated near the leaf base. In our experiments, X.c.gr.mniiiis was readily isolated from young leaves and tillers, and especially from leaf bases.…”

Draft Genome Sequence of the Xanthomonas bromi Type Strain LMG 947

“…and thus suggest a high genetic distance for both X. bromi and X. translucens . Several studies on the pathogenesis ( 4 , 5 ) and genome mining of virulence-related traits ( 6 ) have contributed to an understanding of the underlying mechanisms of bacterial wilt caused by X. translucens pathovars; however, no genome information was available for X. bromi . Reports on bacterial wilt caused by X. bromi indicate a wide distribution of this pathogen throughout New Zealand and France among a variety of different Bromus spp.…”