The effect of ringbarking Brachystegia spiciformis Benth., Julbernardia globiflora (benth.) Troupin and Terminalia sericea Burch. ex DC. trees at different heights with or without the addition of a picloram/2, 4-D mixture.

Abstract

Trees were ringbarked at three different heights relative to ground level (1 000 mm above the ground, at ground level and 100 mm below ground level). In a separate trial, arboricide was applied at four different rates to the lower lip of the ringbarked trees either 1 000 mm above the ground or at ground level. Ringbarking without the arboricide was most effective when carried out in February and at a height of 1 000 mm above the ground. Application of a pricloram/2, 4-D mixture to the lower lip of ringbarked trees in January or April resulted in higher kill rates than applications made in June or October. Using this method, somewhat less picloram was necessary than was required to effect the same kill rate to these tree species by applying the arboricide to cuts in their stem bases. In both trials, the kill rate was positively related to the amount of coppice removed.

Keywords: arboricide; brachystegia spiciformis; bush control; coppice; girdling; height; julbernardia globiflora; kill rate; method; picloram; ring-barking; terminalia sericea; trees; zimbabwe