Improved Weed Control Methods in Maize (Zea mays L.) By Using Single Herbicides and Their Combinations at Reduced Rates with Mineral Oil Adjuvant

A field experiment was carried out in Mallawy Agricultural Research Station, Agricultural Research Center, El-Minia Governorate, during 2015 and 2016 seasons to evaluate the efficacy of certain single herbicides at full rate and their mixtures at reduced rate (50 % of full rate) with mineral oil on weed control and maize productivity. Each experiment comprised of fourteen treatments as follow: the first five treatments were pendimethalin, s-metolachlor, acetochlor, nicosulfuron and dicamba+topramizonused as single herbicidesat full rate 682.5, 672, 840, 24 and 63 g a.i./fed., respectively, the next six treatments were the sequential application of the same previous herbicides at half of the rate plus mineral oil at 1 % v/v and the last three treatments were (foramsulfuron sodium 3.35 %  + iodosulfuron–methyl sodium 0.11 + thiencarbazone–methyll1.07) used at full rate 22.65 g a.i./fed., hoeing twice and untreated treatment as control. Randomized Complete Block Design (RCBD) with four replications was used. The major weeds were Euphorbia geniculata, Ortega, Xanthium strumarium L., Corchorus olitorius L. and Ipomoea eriocarpa L. as broad-leaved weeds and Echinochloa colonum L. and Brachiaria reptans L. as grasses weeds.
The findings of this study showed that the sequential application of two herbicides with different site of action (pendimethalin or s-metolachlor or acetochlor combination with nicosulfuron or dicamba+topramizon) at reduced rate plus mineral oil at 1 % v/v gave better result in controlling broad-leaved and total weeds than applying the same previous herbicides alone at full rate, while, pendimethalin and s-metolachlor alone at full rate were the best in controlling grasses weeds.

The best total weed control efficiency (91.95 and 91.5 %) was achieved under treatment hoeing twice which was equal statistically with foramsulfuron sodium + iodosulfuron – methyl sodium + thiencarbazone – methyl (91.48 and 90.05 %) and with acetochlor mixture with nicosulfuron at reduced rate plus mineral oil (87.19 and 85.37 %) controlling effect as compared with untreated treatment at first survey in both seasons, respectively. Moreover, those treatments also gave the significantly higher grain yield (28.14, 27.20 and 24.98 ardab/fed.) and (26.90, 25.44 and 23.36 ardab/fed. in the both seasons, respectively), as well as ear grains weight and 100-grain weight as compared with untreated treatment.