Influence of Crop Rotation, Weed Control and Nematicides on Spraing in Potatoes

SUMMARY Surveys made during 1972–75 of 113 potato crops (cvs. Pentland Dell and Pentland Crown) growing in sandy soils, mainly in north Yorkshire, showed that the incidence of spraing caused by tobacco rattle virus tended to decline with an increase in the number of barley crops growth in the three years prior to potatoes. In five potato crops the incidence of spraing was not affected by varying weed control in the preceding barley crop. Field trials during 1973–75 tested the effects of aldicarb, oxamyl, fenamiphos, carbofuran and phorate on the incidence of spraing in cvs. Pentland Dell, Pentland Crown and Pentland Hawk. All these chemicals except phorate decreased spraing, but aldicarb and oxamyl were the most effective. Broadcast applications followed by rotavation seemed more effective than in‐furrow treatments.