Seed potato contamination with fusarial propagules and their removal by washing

Abstract

Seed potatoes from Maine, New Brunswick (Canada), Wisconsin, Minnesota and North Dakota were examined during 4 years for contaminating fusarial propagules on tuber surfaces. The degree of contamination was estimated by counting the number of infections that developed on cut surfaces of 100 pieces cut from 50 tubers removed from the tops of 6 cwt bags. Lesion counts were made after 2-weeks incubation at 13 to 16 C. Of seventy-seven seed stocks examined, 29 developed lesions on 91–100% of the seed pieces. Twenty-four of these heavily contaminated stocks came from Maine and New Brunswick. For the different years,Fusarium solani was obtained from 70 to 90%, andF. roseum from 5 to 28% of the lesions cultured each year. BothFusaria were on potatoes from the different production areas. The infectious propagules were in soil washed or brushed from tuber surfaces, and surface-borne inoculum from the tubers. A preliminary report on identifying contamibefore cutting. Plant emergence and productivity were correlated with tuber contamination.