Chemical control of coppicing shoots of Brachystegia boehmii Taub., Brachystegia spiciformis Benth. and Julbernardia globiflora (Benth.) Troupin. 3. Cut stem application of Tordon 101, Tordon 225, Tordon 155 or 2,4,5-T

Killilea, D.M.; Heelas, B.V.; McNeill, L.

Zimbabwe Journal of Agricultural Research 19(2): 191-203

1981


Accession: 072904775

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Abstract
(1) The concn. of Tordon 101 (picloram + 2,4-D), applied by knapsack-sprayer to the point of run-off, that was required for 80% kill of coppice stools on a rangeland site in Zimbabwe was 11-153 g total a.e. per litre, according to species and season. Spraying in March or April was generally more effective than at other seasons. Addition of ammonium sulphate to the sprays did not increase response. ULV application gave poor control. The other chemicals tested (glyphosate, paraquat and S,S,S-tributyl phosphorotrithioate) caused defoliation but killed few plants. (2) The corresponding effective a.e. concn. for Tordon 155 (picloram + 2,4,5-T) in diesel oil was 13-116 g/litre. Treatments in Dec. or May were more effective than in Sept. (before leaf emergence), B. spiciformis being more resistant than the other species. (3) (by Heelas, B. V.; Killilea, D. M.; McNeill, L.) The water-soluble formulations Tordon 101 and Tordon 225 (picloram + 2,4,5-T) were generally more effective than the oil-soluble formulations Tordon 155 and KOP 250 (2,4,5-T). Arboricide effectiveness was increased 160 times by a 'cambial placement' method, viz. cutting back to expose the original stool and placing the arboricide in pockets made by prising back the bark with a chisel.