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

Abstract

The effect of plant age on the development of bacterial wilt of forage grasses was studied by dipping cut roots of Lolinm perenne L. cv. ‘Svea’ in a suspension of Xanthomonas campestris pv. graminis. The effect of humidity on disease development was studied by cutting leaves with scissors dipped in inoculum, and by spraying inoculum onto unwounded leaves. Young plants were more susceptible to the pathogen than old ones. X.c.graminis was easily isolated from young leaves and tillers, especially from the leaf bases. Disease symptoms were most severe at low humidity. However, high humidity is necessary for infection to take place through stomata and hydathodes.