Mulching soil to increase yield and manage plant parasitic nematodes in cucumber (Cucumis sativus L.) fields: Influence of season and plastic thickness

Experiments were conducted to evaluate the effects of mulching soil with cl ear plastic at different periods of the year, and also of mulching with two thicknesses of plastic on cucumber growth, yield, foliar concentrations of total nitrogen or ammonium, phosphorus, and potassium, soil concentrations of total nitrogen or nitrate, phosphate, and potassium, and rhizosphere po pulation densities of nematodes. Growth of plants in mulched plots often ex ceeded that in control plots. Yields fr-om plots mulched with 0.4-mm-thick plastic for five weeks, commencing December 1, 1995, and for six weeks, com mencing March 18, July 3, and August 2, 1996, and planted immediately after mulching, were greater than those from nonmulched plots. Yields fi-om plot s mulched for six weeks with 0.2-mm-thick plastic, commencing August 2, 199 6, were not significantly different from control yields presumably because the plastic deteriorated within four weeks. Rotylenchulus reniformis and He licotylenchus erythrinae were the most frequently detected phytoparasitic n ematodes. At the end of the mulching period, population densities of parasi tic and nonparasitic nematodes in plots mulched with the thicker plastic in March and October and with both thicknesses of plastic in August were lowe r than those in control plots. Foliar and soil concentrations of nutrients usually were similar for mulched and nonmulched plots. Increased growth and yield of cucumber plants in mulched soil were, thus, closely associated wi th the reduction in soil population densities of parasitic nematodes rather than with changes in soil fertility.