Control of Imperata cylindrica and Ischaemum muticum with glyphosate using CDA technique
1990
Leng, T. | Maclean, R.J.
Imperata cylindrica and Ischaemum muticum are two notorious perennial weeds in Malaysian plantations. Both weeds can have very significant depressive effect on the performance of oil palm and rubber. Chemical control at very high spray volume has been the norm in the control of these two weeds. High carrier volume of herbicide implies low labour productivity and high labour cost. Availability of clean water in sufficient volume during dry season could also be a problem in the use of controlled droplet applicator (CDA sprayer) as compared to conventional knapsack sprayer (CKS) in general weed control. To take further advantage of low spray volume in the use of CDA sprayer five trials were conducted to evaluate the suitability of CDA technique in the control of Imperata cylindrica and ischaemum muticum. In view of the massive rhizome mass of both weeds a tranlocative herbicide in the form of glyphosate was selected for use in all the trials. Results of 3 trials on Imperata cylindrica in open condition are summarised below: i) In Trial 1 glyphosate at rates up to 2 kg ae/ha did not provide satisfactory control irrespective of CKS and CDA sprayer used. Poor efficacy of glyphosate was attributed to high watertable and wet ground conditions at the trial site during the entire trial period. ii) Results of Trial 2 and 3 established interaction effect between rate of glyphosate and spray volume on the control of Imperata cylindrica with CDA. At low rate of glyphosate (1.55 kg ae/ha) increase in spray volume from 55 L/ha to 115 L/ha improved the efficacy of control. At medium rates of glyphosate (2.85-3.00 kg ae/ha) spray volumes exceeding 60 L/ha gave satisfactory control. At high rates of glyphosate (3.60-4.30 kg ae/ha) excellent control of the weed was also obtained at spray volume as low as 45 L/ha.
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