Different rates of granular formulations ofaldicarb,
carbofuran,
ethoprop,
fensulfothion, and
phenamiphos were applied directly onto garlic seed cloves in the seed furrow in sandy
clay loam,
clay loam, and loam
soils at planting to assess efficacy for control of Ditylenchus dipsaci in infected seed cloves. All treatments were compared to hotwater-
formalin clove dip disinfection treatment and to nontreated infected controls.
Aldicarb and
phenamiphos at 2.52 and 5.04 kg a.i./ ha, but not at lower rates, effectively suppressed
infection by D. dipsaci and increased yields. Although both nematicides slightly slowed the rate of plant emergence, normal stands were established. Trace levels of
infection occurred in all treatments, including the hotwater-
formalin dip.
Carbofuran at 5.04 kg a.i./ha controlled the nematode but was phytotoxic.
Ethoprop was phytotoxic.
Fensulfothion did not control D. dipsaci even at the highest application rate, 8.90 kg a.i./ha. Single and multiple applications of
oxamyl at 1.12-8.96 kg a.i./ha, applied as a surface spray or in furrow irrigation water, slowed the early progression of disease symptoms but failed to provide season-long nematode control.