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Effect of Compost Amendment or Straw Mulch on Potato Early Dying Disease

Single potato plants (Solanum tuberosum) cv. Superior were grown in field microplots to evaluate the effects of spent mushroom compost or straw mulch on early dying of potato caused by Verticillium dahliae and/or Pratylenchus penetrans. Prior to planting, soil was fumigated, placed in field microplots, and then infested with pathogens. Area under the senescence progress curve (AUSPC) was greater for plots infested with V. dahliae and/or P. penetrans than for noninfested plots. Plants grown in soil infested with both pathogens developed symptoms earlier than plants grown in soil infested with a single pathogen. Both V. dahliae and P. penetrans reduced yields; the combination of pathogens reduced marketable tuber yields by 22 to 44% (A- and B-sized tubers). Although the total number of tubers of all sizes was not affected by cultural or pathogen treatments, the addition of compost increased marketable tuber weight and decreased AUSPC. Soil amendment with spent mushroom compost may be a means of reducing the effects of potato early dying and increasing tuber yield when one or both pathogens are present.