Studies on parsnip canker

SUMMARY In field experiments at Wellesbourne, reductions in both black and orange‐brown canker of parsnips were obtained either by late sowing (in May or June), or by singling the plants to a narrow interval (3 in.), or by a combination of both treatments. The treatments reduced mean root size, and small roots had less canker than large ones. It seemed that much of the disease reduction obtained was a consequence of the reduction in mean root weight caused by the treatments. There was evidence, however, that the reductions in black canker obtained by late sowing were also dependent to some extent upon the shorter period that the roots were in the ground. Marketing assessments were made on four occasions in an experiment in which crops were grown from seed sown in March and May and were singled to 3 in. or 6 in. in rows 15 in. apart. They showed that the highest total and highest marketable yields were generally obtained from the earlier‐sown crop at the narrower spacing.