Improved store management of diseases affecting seed tubers and its effects on the subsequent crop

There are numerous pathogens which damage potato seed health, with significant economic and agronomic consequences. Seed disease impacts greatly on potential markets whereas an established reputation for healthy seed enables new business opportunities to be exploited. The aim of the project was to examine the effects of different storage regimes on seed-borne diseases and seed tuber quality attributes and how these regimes impact on the subsequent agronomic performance of the crop. Three pathogens Fusarium coeruleum (dry rot), Helminthosporium solani (silver scurf) and Phoma exigua var. foveata (gangrene) were the major disease targets of the study.

Storage treatments included two pull-down regimes, good (1°C/day) and poor (0.25°C/day), two storage temperatures, low (3°) and (5°C), each with and without fungicide treatment. Generally there was a clear difference between the different pull-down regimes with a lower incidence of this disease found in good compared to poor pull down regimes. Application of fungicide reduced the incidence of silver scurf in most storage treatments. 

Despite widely contrasting seed storage regimes having an effect on both disease development and sprouting, they generally had limited or no effect on final yield in either variety. Extensive sprout development following storage at 5°C advanced emergence but effects on stem and tuber populations were limited and were not consistent across experiments. Fungicide treatment consistently delayed emergence although virtually complete emergence was eventually achieved. The study was unable to establish the impact of seed disease thresholds on field disease, in part because the relationship between pathogen DNA on the tuber and disease was not direct.