Trunk Injection Method for Introducing Chemical Formulations in to Rubber Trees

Abstract

Natural Rubber is an important commodity to the economy of Sri Lanka. This industry makesexport earnings, sustain the livelihood of over thousands of people, supplement thousands ofhectares to the forest cover and provide many other socio-economic and ecological benefits.The economically important diseases are regarded as a major constraint for achievingpotential productivity levels of rubber cultivations. Hence management of these diseasesprovides economic benefits to rubber growers. The most popular method of disease control ischemical control. There are various chemical application techniques and spray applications,soil drenching, dusting or broadcasting are popular methods. Based on the age, type of thedisease or the prevailing weather conditions, the application technology needs to be changed.These conventional technologies have many health and environmental drawbacks. Therefore,economical and environmental friendly chemical application techniques have becomeimportant. The present study was aimed at investigating the trunk injection method forintroducing chemical formulations into trees. Several types of potential injectors are availableand the chemjet injectors described by Guest et al., (1994) was used throughout theexperiments. These injectors [Chemjet Trading (Pvt) Ltd, Australia] contain 20ml of thesolution and have a working pressure of 1 – 1.5 bars facilitating the formulation into the treesthrough drilled holes. The injection process was tested at Dartonfield Estate, on the Heveabrasiliensis clone RRIC 121. The average girth at the tested plants was 89 cm. Two analysesviz. 45, 60 to a depth of 4 cm from the outer bark was done. The uptake rates weredetermined using 8% tebuconazole in aqueous solutions. Uptake of the fungicide was slightlyhigher in deep injected method compared to shallow injection. The two angles tested againstthe liquid uptake too were not significantly different from each other. No interaction wasobserved among the injection angle and the depth of injection on the liquid uptake. More than70% of the trees had uptaken the entire 20ml injected volume within 48 hrs of injection.Trunk diameter had no effect on the uptaking process. The results obtained proved thepossibility of injecting liquids / chemical solutions into rubber trees. Trunk injection requireslow volumes of chemicals resulting in reduced cost in chemical applications. Minimumwastage of chemicals could be achieved together with reducing the impact of hazardouschemicals on the environment. Compared to the currently practiced chemical applicationmethods into trees, this application technique has many advantages.