Synergistic interaction between plant-feeding nematodes and the fungus rhizoctonia solani in potato

• Stem canker caused by the pathogenic fungus Rhizoctonia solani is a major problem for potato cultivation throughout Sweden, especially as it leads to great economic losses. Advisors and growers have developed a theory that there is a correlation between the severity of stem canker and plant-feeding nematodes, as high occurrences of stubby-root and rootlesion nematodes were found in potato fields with high incidence of stem canker. The aim of this project was to investigate any interactions between these nematodes and the fungus under controlled conditions. In the first experiment, pregerminated minitubers (cv King Edward) were planted in pots with sterilised sand and placed in a climate chamber at conditions corresponding to a Swedish spring. Fungal mycelium and/or nematodes (Pratylenchus penetrans) were added to the pots in various combinations. The pots were harvested ten weeks after inoculation and the parameters measured were fresh and dry weight of stems, stolons, tubers and roots, as well as the gradation of the damage caused by the nematodes and the fungus of the different plant parts. The nematodes produced feeding symptoms on stems, tubers, stolons and roots, but the roots also became brownish to different degrees. The fungus caused stem canker of different severity on the stems, burned off stolons and produced sclerotia on the roots and on the majority of the tubers. We found a synergistic effect between R. solani and P. penetrans, as the tuber yield decreased significantly when both nematodes and fungus were present in the pots.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Jordbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Agricultural Science (hsv//eng)

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