Summary
Pentachloronitrobenzene (PCNB) controlled potato scab in fine sandy loam of the Yakima Valley when applied at the rate of 50 pounds per acre broadcast before planting and mixed by discing or rotary tillage. Mixing with a harrow in the top 2 inches of soil was ineffective even when 80 pounds per acre were used. Control was also unsatisfactory when the material was applied after shallow planting followed by harrowing and hilling.
The stem-canker stage of rhizoctonia was controlled similarly with PCNB at the rate of 10 to 20 pounds per acre. Tuber sclerotia, however, were not controlled until rates of 40 to 50 pounds per acre were used. At these rates there was no reduction in total yield of tubers but some delay in emergence resulted. Limited data indicate only slight residual disease control in the second year.
These results were obtained with irrigation on fine sandy loam low in organic matter but at very high levels of infestation of the pathogens. Observations indicate that undecomposed plant residue in the soil may interfere with mixing and thus seriously reduce the effectiveness of treatment.
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Contribution from the U. S. Department of Agriculture, Agricultural Research Service, and the Washington Agricultural Experiment Stations, cooperating. Published with the approval of the Director as Scientific Paper No. 1567, Washington Agricultural Experiment Stations.
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Menzies, J.D. Dosage rates and application methods with PCNB for control of potato scab and rhizoctonia. American Potato Journal 34, 219–226 (1957). https://doi.org/10.1007/BF02855942
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DOI: https://doi.org/10.1007/BF02855942