1Contribution from Department of Agronomy, College of Agriculture, G. B. Pant Uni-versity of Agriculture and Technology, Pantnagar U; P. Pin-263145.
2,4-Dichloro-phenoxy acetic acid (2^-D) is a recommended herbicide for control of broadleaf weeds in wheat (Triticum aestivum L.). Malformation of spikes has been observed when 2,4-D was sprayed during the early stages of crop growth. Wheat plant escapes this injury when sprayed at 35 days after sowing.
Intraspecific differential response was observed in wheat. Varieties like Sonalika (RR-21) and UP-310have been found to be relatively more susceptible than Kalyansona and Moti. The spike malformation was exhibited as looped, gappy, branched, and elon-gated spikes.
Better fertilized crop was found to produce more malformed than poorly fertilized crop. Tank mix spray of 2,4-D at 0.50 kg/ha and six percent urea (volume = 500 lit/ha) did not alter the malformation behaviour.
Significant yield reduction in wheat was observed when 2,4-D was sprayed before 30 days after sowing as compared to late applications and weedfree check. Mixed application of 2,4-D and urea did not increase the wheat yield.
