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Effects of Metam-Sodium Applied by Drip Irrigation on Root-Knot Nematodes, Pythium ultimum, and Fusarium sp. in Soil and on Carrot and Tomato Roots. P. A. Roberts, Extension and Associate Nematologist, University of California, Kearney Agricultural Center, Parlier 93648. A. C. Magyarosy, W. C. Matthews, and D. M. May. Research Scientist, Department of Plant Pathology, University of California, Berkeley 94720; Staff Research Associate, University of California, Kearney Agricultural Center, Parlier 93648; and Farm Advisor, University of California Cooperative Extension, Fresno 93702. Plant Dis. 72:213-217. Accepted for publication 14 September 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0213.

Efficacy of metam-sodium in sandy loam and sandy clay loam soils was compared with that of dichloropropene (1,3-D) fumigation for control of Meloidogyne incognita and M. javanica and Pythium ultimum and Fusarium sp. on tomato and carrot. Metam-sodium (32.7% a.i.) was injected continuously through drip irrigation lines on tomato and carrot beds before planting at rates of 63702 L/ha in from 2.5 to 14.2 cm water. Applications treated the central 5075% of the bed width. Metam-sodium at all rates significantly reduced nematodes in soil before planting, as well as root gall ratings at midseason and harvest, and increased yield in most cases. The 63-L/ha rate was less effective than higher rates. These efficacious metam-sodium responses were similar to those obtained with 1,3-D at rates of 75144 L/ha. For P. ultimum and Fusarium sp., metam-sodium at rates of 187702 L/ha reduced the number of sporangia and propagules per gram of dry soil, respectively, and the number of infections per 50 cm of tomato root. Metam-sodium applied by drip irrigation is an effective preplant alternative treatment to 1,3-D for nematode control in tomato and carrot, with the possible added benefit of reducing certain fungal root pathogens.

Keyword(s): fumigation, soil treatment.