VIEW ARTICLE

Interactions of Herbicides and Nematicides with Root Diseases of Snapbean and Southern Pea. Donald R. Sumner, Assistant Professor, Department of Plant Pathology, University of Georgia Coastal Plain Station, Tifton 31794; Phytopathology 64:1353-1358. Accepted for publication 24 May 1974. DOI: 10.1094/Phyto-64-1353.

In greenhouse experiments treating soil with trifluralin + dinoseb increased foliage wt and decreased root discoloration of snapbean, but treating soil with ethoprop had the opposite effect. Plants grown in soil treated with all three pesticides were similar to plants grown in nontreated soil. DBCP, trifluralin + dinoseb, and ethoprop reduced growth and increased damping-off of snapbean in soils infested with Pythium myriotylum. In contrast, treatment with ethoprop alone increased root rot in soil infested with P. irregulare, but treatment with trifluralin + dinoseb reduced root rot. Root rot of snapbean was most severe in soil infested with Rhizoctonia solani, or a combination of several fungi, and only treatment with dimethyl tetrachloroterephthalate increased root rot while none of the pesticide treatments decreased root rot. Root disease in snapbean was increased by treating with ethoprop in soils infested with Fusarium roseum and foliage wt was reduced in soil infested with F. solani. Effects of pesticides on snapbeans in soil infested with F. oxysporum or Sclerotium rolfsii were variable. Pesticides did not significantly affect root disease and foliage wt in southern pea. Inoculum density of F. solani was significantly increased in soil by treatment with trifluralin + dinoseb 1 day after snapbeans were planted, but there were no significant differences when plants were harvested 27 to 28 days later. Pesticides did not significantly influence inoculum density of F. oxysporum or F. roseum.