Soil conditions and root diseases V. Symptomatology of wilted cotton and red gram

Abstract

1. Wilt symptoms in cotton and red gram caused by the soil-borne pathogens F. vasinfectum and F. udum as seen by the naked eye and clearly made out by photographing with tricolour red filter on panchromatic film are recorded. 2. Wilt symptoms in cotton when sown in F. vasinfectum infected soils appear on the seventh day in variety M. 9 and thirteenth day in variety K. 2 after germination of the seeds as very distinct vein clearing discernible to the eye in cotyledonary leaves. Later, the first leaves also show vein clearing not clear to the eye but detectable by photographing with tricolour red filter. 3. Wilt symptoms in red gram by F. udum do not culminate in vein clearing as in cotton although there is a general and well-marked dechlorophyllation presenting almost a toxemic condition. This is first seen on the eighteenth day after germination. 4. The possibility of these vascular wilts interfering with the normal uptake of some of the essential chlorophyll forming heavy metals is discussed.