The results of a study of the action of 77 different substances on Acroptilon picris , Centaurea picris
Lobov, V.P.; Kalinin, F.L.; Leppik, L.A.
Nauchn Tr Ukrainsk Nauchn Issled Inst Fiziol Rast 23: 173-183
The study was made in the Ukrainian Scientific Research Institute of Plant Physiology. When methylene chloride and its distillation residues (I), carbon tetrachloride and other chloride mixtures were applied to the soil to a depth of 25-30 cm at 5-7 metric tons/ha, the root system of A. picris died off to a depth of 2-2.5 m. Winter wheat sown 15, 30, and 90 days after the application of I to the soil grew and developed normally. Spraying with trichloroacetic acid and its derivatives at 25-100 kg/ha, or with DCU, Fenuron, Monuron, CIPC, Simazine, or Atrazine (at 5-20 kg/ha) caused the death of all the above-ground organs of A. picris. Low effectiveness was shown by preparations having contact action when they were sprayed on the aboveground part of the plants or applied to the soil. The application of the triethanolamine salt of maleic acid hydrazide at 30 kg/ha delayed the formation of buds and the growth of the stem. Spraying esters or salts of 2,4-D on grain sowings at 1-5 kg/ha prevented the formation of A. picris seeds; if used over a long period of time it caused complete extermination of the weed. Data are also given on the translocation and distribution in A. picris roots of radioactive 2,4-D labelled on the carboxyl group.