A seed treatment for the control of Pythium damping‐off diseases and Peronospora parasitica on brassicas

SUMMARY In soil inoculated with Pythium ultimum or Pythium irregulare, seed treatment with either Apron 70 (=1 g metalaxyl and 1 g captan/kg seed) or thiram gave control of pre‐emergence damping‐off of Brussels sprout and cabbage seedlings. On cauliflower, Apron 70 was significantly more effective than thiram. No post‐emergence damping‐off occurred in either of these crops or in oil‐seed rape following seed treatment with Apron 70 whilst post‐emergence losses from untreated seed ranged from 10·2–19·4% and from thiram treated seed from 5·7‐7·4%. Apron 70 gave complete control of Peronospora parasitica on cauliflower inoculated 10 days after sowing; thiram was ineffective. Following seed treatment with Apron 70, metalaxyl was detected in the cotyledons, true leaves and roots of cabbage seedlings up to 4 wk from sowing.