Effects of rotation length, fungicide treatment of seed tubers and nematicide on diseases and the quality of potato tubers

Abstract

SummaryIn 1982 – 88, potatoes were grown in 2‐, 4‐ and 6‐course rotations with spring barley on a field infested with Globodera rostochiensis. Severity of stem canker and black scurf increased with increasing frequency of previous potato crops, and seed tuber treatment with tolclofos‐methyl became less effective in controlling diseases. This suggested that previous crops had increased the amounts of soil‐borne inoculum of Rhizoctonia solani. Oxamyl soil treatment increased stem canker in one year and decreased black scurf in four years.Seed tuber treatment with imazalil or prochloraz decreased stem base infection by Polyscytalum pustulans and skin spot and silver scurf on tubers. Black dot was prevalent on tubers in all years and was not affected by seed tuber treatment or previous cropping. Oxamyl increased black dot and common scab in five years and decreased % tuber dry matter in six years.Cysts of G. rostochiensis were found attached to Désirée but not to Maris Piper tubers in August. At harvest tubers of both cultivars were affected by superficial pitting and its severity was related to soil populations of G. rostochiensis at planting. This damage was controlled by oxamyl. It is suggested that the pitting developed from holes made in the tuber skin at larval invasion.In 1989, Désirée seed tubers and healthy mini tubers were planted in all plots and severity of stem canker and black scurf increased with increasing proximity of previous potato crops and with the number of previous crops. Black dot on stems and tubers was not affected by previous cropping but was much less severe in a plot that had not grown potatoes during the seven years of the experiment. The severity of common scab generally decreased as the number of preceding potato crops increased.

Influence of crop rotation and conservation tillage practices on the severity of soil-borne potato diseases in temperate humid agriculture

“…Although H. solani is a pathogen of tuber-bearing Solanum species only (Rodriguez et al 1995), saprophytic colonization of senescing alfalfa, sorghum, rye, oats, corn, wheat, rapeseed, red clover, and buckwheat was also observed, suggesting a mechanism for overwinter survival (Mérida and Loria 1994). Based on the apparent presence of soil-borne inoculum, crop rotation has been suggested as a management tool for control of silver scurf (Hide and Read 1991;Secor and Gudmestad 1999).…”

“…Crop rotation has often provided little benefit for control of common scab (Scholte 1990;Hide and Read 1991), since the ability of pathogenic Streptomyces spp. to survive in soil or on plant residues for over a decade can circumvent any short term rotation benefits (Kritzman and Grinstein 1991).…”

“…The duration and frequency of crops in a potato rotation can influence potato soil-borne disease incidence and development (Specht and Leach 1987;Hide and Read 1991;Honeycutt et al 1996). For example, continuous potato production has been shown to result in 58% of plants developing stem lesions caused by Rhizoctonia solani Kühn, as compared to 12 to 22% stem disease in potatoes grown with other rotation crops (Honeycutt et al 1996).…”

Development of Rhizoctonia solani on Stems, Stolons and Tubers of Potatoes I. Effect of Inoculum Source

“…In contrast, our results indicated that soil inoculum only occasionally played a significant role in stem and stolon disease incidence. Previous studies have shown that disease incidence increases with increasing soil inoculum level and potato cropping frequency (Banville 1989;Hide and Read 1991;Gilligan et al 1996). Gilligan et al (1996) showed that when following a susceptible rotation crop 70% to 80% of potato plants could become infected from soil-borne inoculum.…”

Effects of herbicides on growth and survival, and influence of latitude on anastomosis group diversity in Rhizoctonia solani

“…This has led to epidemics of many plant diseases including those caused by Rhizoctonia solani (Hide and Read, 1991;Huiskamp and Lamers, 1992). On the other hand, decline in Rhizoctonia diseases also has been observed with mono-culture in raddish (Wijetunga and Baker, 1979) and potatoes (Jager and Velvis, 1980).…”