Crop rotation can confer resistance to potatoes from Phytophthora erythroseptica attack

Abstract

The influence of 2- and 3-yr crop rotations and conservation tillage practices on the severity of pink rot of potato (causal agent: Phytophthora erythroseptica) was examined in Prince Edward Island, Canada. The 2-yr rotation crops included spring barley and potato (cv. Russet Burbank), and the 3-yr rotation was comprised of barley (undersown with red clover), red clover and potato. In the potato year only, the main plots were split to examine conventional and minimum tillage (sub-plot) treatments. Soil samples and potato tubers were extracted from field plots 6-7 yr after the initiation of the field trial. Following post-harvest inoculation of field-grown tubers with P. erythroseptica, we determined that pink rot disease development was significantly (P = 0. 05) less pronounced in potatoes from 3-yr rotational than from 2-yr rotational soils. The effect of tillage management was not significant. Potato plants grown in greenhouse trials in 3-yr rotational soils (from field plots) were significantly (P = 0.05) less diseased than those grown in 2-yr rotational soils following inoculation with P. erythroseptica. These results suggest that potato plants grown in soils managed under a 3-yr rotation are intrinsically more resistant to pathogen attack than those managed under a 2-yr rotation. We confirmed that crop rotation provides disease control benefits beyond those normally associated with pathogen population decline in the absence of the susceptible host. The possibility that beneficial soil microflora and tuber endophytes were involved in disease suppression is discussed. Key words: Phytophthora erythroseptica, pink rot, potato, Solanum tuberosum, crop rotation, minimum tillage, beneficial endophytes, biocontrol