Efficacy of four systemic nematlcides against Radopholus similis in coconut nursery

Four systemic nematicides, aldicarb, carbofuran, phorate and phenamiphos at 10, 15 and 25 kg a.i./ha, applied three times at the same rate for a period of one year against the burrowing nematode, Radopholus similis in coconut nursery, were evaluated. In general, all the treated plants recorded significant increase in plant growth but this increase was not consistent with increase in dosage of chemicals. Carbofuran @ 15 kg a.i./ha recorded maximum plant growth compared to 10 or 25; kg a.i./ha. Except 10 kg a.i./ha of aldicarb and 10 and 25 kg a.i./ha of carbofuran all the other dosages and chemicals reduced nematode population significantly. At all dosages, aldicarb treated plants recorded maximum plant growth compared to respective doses of the other three chemicals. Phorate and phenarniphos, at all three levels, were found to decrease the nematode population significantly but plants treated with phenamiphos always recorded better plant growth than phorate. There was no significant difference between three dosages of phorate and phenarniphos in the control of nematodes as well as their effect on plant growth. Complete control of R. similis was obtained with pheftamiphos and phorate @ 25 kg a.i./ha. Thus application of phenamiphos or phorate @ 25 kg a.i./ha is recommended for release of nematode free seedlings from infested coconut nurseries.