NEMATODE INFESTATION SYMPTOMS ON BARLEY AS A MEANS OF DETERMINING THE EFFICIENCY OF CHEMICALS AS LETHAL AGENTS AGAINST TYLENCHUS DIPSACI KUHN

Abstract

Barley is suggested as a detector crop for the presence of living nematodes, Tylenchus dipsaci, in soil, owing to rapid development of nematode disease symptoms on barley.A satisfactory source of inoculum consists of the white masses of coiled nematodes that can be seen when the basal plate is removed from badly diseased narcissus bulbs. These masses remain viable for six months or longer when removed from the bulbs.Low temperatures and high light conditions favor the development of the nematode disease symptoms in barley seedlings, after nematodes are transferred from narcissus bulb to autoclaved soil planted with barley. Such barley seedlings were broad-leaved and stocky. Under low light and high temperatures, conditions that favor the development of spindly seedlings, the nematode disease symptoms are inconspicuous or absent.Few chemicals appear to be lethal to the bulb nematode. Of 100 tested only phenol, silver nitrate, and potassium or sodium bisulphite were lethal at dilute concentrations.