Effects of inoculum source and irrigation on black dot disease of potatoes (Colletotrichum coccodes (Wallr.) Hughes) and its development during storage

The effect of seed-and soilborne inoculum ofColletotrichum coccodes on the incidence of black dot on potatoes

“…The above results confirmed the importance of soilborne inoculum of C. coccodes (Read & Hide, 1988, 1995: Read, 1991: Hide et al, 1994. It also showed that the contribution of soil-borne inoculum (P<0.001) to the incidence of black dot on progeny tubers is at least twice that of seed-borne inoculum, even when seed is severely infected with the pathogen.…”

“…Infection of tubers by C. coccodes originates primarily from inoculum on seed (Jellis & Taylor, 1974), or from microsclerotia occurring free or on colonised plant debris in soil (Blakeman & Hornby, 1966). According to Read & Hide (1988) the incidence of black dot on the progeny of disease-free tubers increased by augmenting C. coccodesinfested soil with laboratory-cultured inoculum of the pathogen, while Read (1993) indicated that seed infection, unless severe, is only important early in the season when soil inoculum level is low. However, no conclusive evidence has been presented concerning the quantitative contribution of the respective sources of inoculum to black dot incidence.…”

Treatment of seed potatoes with prochloraz for simultaneous control of silver scurf and black dot on progeny tubers

“…Of the fungicides previously reported effective against silver scurf, prochloraz appears to have the most pronounced inhibitory activity on growth (but not spore germination) of C. coccodes (Marais, 1990: Read & Hide, 1995, although the latter authors found it less effective for field control of black dot and silver scurf than fenpiclonil. Nevertheless prochloraz prevented increase in black dot on treated tubers during storage (Read & Hide, 1988).…”

“…It should nevertheless be emphasised that the present experiments were conducted in fallowed virgin soil not harbouring the two fungi. Unlike H. solani, which is almost exclusively tuber-borne (Jellis & Taylor, 1977a" Dashwood et al, 1991, infection by C. coccodes originates from tuber-borne and soil-borne inoculum (Jellis, 1972: Komm & Stevenson, 1978: Read & Hide, 1988. In the presence of soilborne C. coccodes, control of black dot by prochloraz could therefore be less effective.…”

A Comprehensive Overview on Black Scurf of Potato

“…Excessive soil moisture may affect potato tubers and lead to swollen lenticels and increased susceptibility to tuber borne infections (Adams and Stevenson, 1990). Moderate soil moisture was also to be conducive for black dot infection and disease development (Read and Hide, 1988).…”