ABSTRACT

Residue of some of herbicides in oil palm cropping systems might have negative effects on some arable crops intercropped within the palm inter-rows.The study determined the residual effect of Indaziflam herbicide on some common arable crops, the relative persistence of varied concentration of Indaziflam in the soil and the effect of applied Indaziflam on weed seed bank. This is with a view to providing information on effecting proper weed management strategies in oil palm cropping systems. The experiments were carried at the greenhouse and field of Nigeria Institute for oil palm (NIFOR) Benin – City Edo State for two years cropping season 2016 and 2017. The experiments were conducted in a completely randomized design in three replicates. Experiment one consisted of Indaziflam concentrations of (0.000 , 0.0045,  0.0090, 0.0135, 0.0180, 0.029,  0.0315, 0.0360, 0.0360,  and 0.045 kg a.i  ha-¹) and five separate times of soil sampling for growing maize, cucumber, melon and tomato. While experiment two consisted of untreated plot as control, glyphosate applied at 1.5 kg a.i ha^-1, tank mixture of glyphosate plus diuron at 2.0 kg a.i ha^-1+ 1.5kg a.i ha^-1, glyphosate followed by Indaziflam ten days later at 1.5kg a.i ha^-1+ 0.04 kg a.i ha^-1, glyphosate followed by Indaziflam ten days later at 1.5 kg a.i ha^-1+0.05 kg a.i ha^-1, tank mixture of glyphosate plus Indaziflam at 1.5 kg a.i ha^-1+0.04kg a.i ha^-1, tank mixture of glyphosate plus Indaziflam at 1.5kg a.i ha^-1+0.05kg a.i ha^-1, indaziflam at 0.05 kg a.i ha^-1 Indaziflam at 0.045kg a.i ha^-1as herbicides treated plots and five separate times of soil sampling for growing maize, cucumber, melon and tomato. In the last experiment, soil samples were collected from the herbicides treated plot and placed in screen house for soil seed bank study.The results show that maize, cucumber, melon and tomato dry weight loss decreased as the soil samples time for application of indaziflam increased from 0-4 weeks . Germination of maize, cucumber, melon and tomato increased as the time of soil sampling after herbicide application increased from 0 - 16 weeks. Weed seed emergence was highest in the control plot and higher in glyphosate treated plot, but lower at 0 weeks of soil sampling after herbicide application with weed density of 100 m^-2 at 16 weeks of applied herbicides . In plots treated with tank mixture of glyphosate plus diuron, weed seed emergence density was between 5 m^-2 and 7 m^-2 at 0 weeks of soil sampling and was 100 m^-2 and 120m^-2 respectively at 16 weeks of soil sampling. In other plots where Indaziflam was tank mixed with glyphosate, used singly or applied ten days after glyphosate treatment had lower weed density up to 16 weeks of soil sampling after herbicide application. In conclusion indaziflam affect the height and dry weight of maize, melon, cucumber, and tomato till 12 weeks after herbicide application. However, the period of 16 weeks has to lapse before intercropping maize, melon, and cucumber in oil palm farm.