Chemical control of blackleg, dry rot and verticillium wilt of potato

Summary

A number of chemical proprietary compounds were tested for the control of blackleg, dry rot and Verticillium wilt in potato. In most, but not all instances, blackleg was controlled by treatment of seed pieces with mercuric chloride, Semesan Bel or Agristrep. Phygon, Spergon, Dithane Z78, Captan, Terramine, Karathane, Sulfuron, Kolo 100, and Lime gave little or no control.

Dry rot and Verticillium wilt originating in seed stocks were controlled by seed treatment with Semesan Bel and acid mercuric chloride. Captan, Spergon, Phygon, Dithane Z78 and Agri-mycin 500 proved ineffective. Dry rot in stored potatoes was most effectively controlled by tuber treatment with Semesan Bel or Agri-mycin 500 (42.4 per cent copper).

Combinations of two or more of these diseases were controlled by Semesan Bel alone and by combinations of Semesan Bel and Agristrep, but not by combinations of Captan and Agristrep. Pronounced phytotoxicity always followed treatment with mercuric chloride, and occasionally followed treatment with Semesan Bel, but under good cultural conditions Semesan Bel gave marked disease control and did not adversely affect stands.