Distribution of bacterial wilt and races and biotypes of the pathogen in India
Abstract
The bacterial wilt incited by Pseudomonas solanacearum Smith was endemic in India throughout the west coast, central and Deccan plateau of Karnataka, Western Maharastra and Madhya Pradesh, in the eastern plains of Assam, West Bengal and Orissa and Chotta Nagpur plateau on potato, tomato, brinjal, chillies and wild Datura metel; the incidence being 10 to 50%. In the North-western (alt. upto 2200 m), Eastern and Southern hills it was also endemic but affected only the potato; the incidence being 5 to 30%. The disease was more widespread in heavy and acidic (pH 3.5–6.5) soils than in light and neutral (pH 6.5–7.5) to alkaline (pH 7.5–8.5) soils. It was not observed in Bundelkhand and northern Malva plateaus, North-central and North-western plains where mean monthly maximum temperatures remain above 40°C accompanied with water deficit in soil continuously atleast for 45 days during summer and in the high hills (above 2200 m) where mean monthly minimum temperature during December–February remain below 0°C.
In the hills only the race-3 and biotype II of the pathogen were prevalent, while in the eastern plains and Deccan and central plateau race 1 and biotype III were predominent; biotype IV was recorded only at a few places.
