THE ECOLOGICAL EFFECT OF SOME WILD OAT (Avenafatua L.) HERBICIDES ON WHEAT CHARACTERISTICS

Abstract

Four field experiments were carried out during 1994/95 and 1995/96 seasons at El­ Nubaria Res. Station (ARC), Egypt to evaluate the efficiency of some graminicides applied at two spraying dates to control wild oat (Avenafatua) in wheat fields. Bread wheat variety Sakha 69 was used in both seasons.

Each of the two experiments for each season dealt with one time of herbicides spraying date (30 and 60 days from planting). Each trial consisted of six weed control treatments, four herbicide treatments (Grasp, Illoxan, Suffix and Puma-S-), one unweeded check, and one handweeding check.

Results revealed that weed control treatments (herbicides and hand weeding) significantly reduced fresh and dry weights and number of wild oats. Spraying at 30 days after sowing was more effective to reduce fresh and dry weights of wild oats. Tralkoxydim (Grasp) was the potent herbicide in this respect, whereas the rest graminicides were found with comparable efficiency.

The heavier of wild oat infestation occured, the more the decline befell in wheat yield and yield attributes. Therefore, no treatment performed better than Grasp whereas Suffix and Illoxan were equivalent. In addition, early spraying date (30 days from planting) is favourable from the view point of wild oat control performance as well as the desirable wheat yield and yield componentS.

Weed control treatments did not cause significant alteration in carbohydrate content % of wheat grains. However, protein contents seems to be higher in favour of chemical weed control treatments then hand weeding; late spraying date then early one and in the first growing season than the second one. At harvest, Grasp residue in grains was less than straw indicating 0.450 and 0.793 ppm, respectively for the early spraying date and 0.489 and 0.832 ppm, respectively for the late spraying date.