The prediction and manipulation of Colletotrichum coccodes on Solanum tuberosum

As all underground parts of a potato plant can be infected with Colletotrichum coccodes it was speculated that it may be possible to predict black dot development on harvested tubers by assessing stems and stolons for the presence of the disease in the growing crop. In a 3-year study stems and stolons were assessed for black dot in 123 potato crops and its incidence related to disease on the tubers at harvest. In cvs Estima and Maris Piper, if stems or stolons showed black dot symptoms as the onset of crop senescence then the disease was likely to be present on tubers at harvest. No relationship between black dot on stems and stolons in the growing crop and disease on tubers at harvest was found in the cv. Saxon. To explain these results a series of glasshouse and field experiments were performed to identify when symptoms of black dot developed on underground parts of a potato plant. Results showed that infection by C. coccodes could occur soon after these plant parts had formed. Visual symptoms did not appear on stems and stolons till just prior to foliage senescence and on tubers until after the start of foliage senescence. Further research considered whether a reduction in black dot symptoms on tubers is achievable through haulm destruction methods in the field. Results indicated that in a crop of cv. Maris Piper, where there was a high incidence of black dot, and no one technique gave a significant reduction in symptom developing on tubers. These inconclusive results are discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo