Effect of some maize herbicides on weeds and yield and residual effect on some following crops (wheat and broad bean).

A major factor limiting yield and quality of maize (Zea mays L.) is the spread of weeds in maize fields. Thus, two field experiments were conductedat sides Agricultural Research Station, Agricultural Research Centre (A.R.C.), during 2013 and 2014 to study the efficiency of four pre-emergence herbicidesat different rates:Acetochlor 84% EC (Harness) at 840, 1260 and 1680 g a.i. fed. (feddan= 4200 m ), Sulcotrione 15% SL 1 2 (Prestige) at 150, 225 and 300 g a.i. fed. , Metribuzin 70% WG (Marrin El-Nasser) at 210, 315 and 420 ga.i. fed. 1 1 and Pendimethalin 45.5%CS (Stomp Extra) 682.5, 1023.8 and 1365g a.i. fed. as well as hand hoeing (twice) and 1 unweeded control on yield, yield components and quality characters of maize. Also, study the residual effect of the four herbicides and their doses on the following winter crops wheat and broad bean. The data revealed that the herbicides used at different rates gave better and wide weed control spectrum of total annual weeds than hand-hoeing and the unweeded control. Dry weight of total annual weeds was generally correlated with herbicide rates, whereas metribuzin at the highest rate (420 ga.i. fed ) gave (85.7, 82.2%) controlling effect, 1 while at the lowest rate of pindemithalin (682.5 g a.i. fed ) gave (57.0, 51.8%) controlling effect, respectively 1 at first survey in both seasons. The yields in all herbicides treatments were significantly greater than the untreated control and there were no adverse effects on grain yield and its quality (Carbohydrate% and protein%), whereas metribuzin at 420 ga.i. fed gave the highest grain yield (29.3, 28.4 ardab fed ) 1 1 (ardab = 140 kg), while pendimethalin at rate 682.5 g a.i. fed gave the lowest grain yield (18.8, 19.4 ardab fed ). 1 1 Regarding the impact of the herbicides used on the following winter crops, results revealed no significant differences innumber of plants per square meter for both wheat and broad bean compared with plots after maize that were devoted to hand-hoeing or to the unweeded control. Therefore, it could be concluded that maize plots that were treated with Acetochlor, Sulcotrione, Metribuzin and Pendimethalin could be sown with wheat or broad bean after harvesting treated maize plants without any harmful effect. Key word: Maize Zea mays L. Pre-emergence herbicides Weed control Residual effect INTRODUCTION and yield through acquisition of required resources Maize (Zea mays L.) is one of the most important constraint on crop production if not controlled [3-5]. cereal crops in Egypt, whereas it is a multipurpose Thus, Massinga et al. [6] founded maize yield was crop (e.g. used as human food, animals and reduced up to 91 percent by compaction with 8 palmer poultry feed, also it produces row materials for amaranth (Amaranthus palmeri L.) plants m of row, starch industry and also used in the preparation of whereas maize grain yield was only reduced 13 to 14 other products. The total cultivated area of maize in 2012 percent by 10 giant foxtail (Setaria faberiL.) plants m was about 2,16 million feddans(=0.907 million hectares) [7]. [1]. To minimize the weed losses, several methods are Weeds are among serious constraints that limit maize available such as mechanical, cultural, biological and production. The competition between weeds and maize is chemical control methods. Exhausted by cultural methods, induced reducing the quality and quantity of maize yield farmers are moving towards other alternative methods of over 30%[2]. In addition, weeds interfere with crop growth weed control [8, 2]. including light, water, nutrients and are potentially a major