Tank-mix application of p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting herbicide (mesotrione, tembotrione or topramezone) with atrazine improves weed control in maize (Zea mays L.)

Field experiments were conducted to identify the effective tank-mix combinations of HPPD (p-hydroxyphenylpyruvate dioxygenase) herbicides (Mesotrione, tembotrione and topramezone) with atrazine for post-emergence grass and broadleaf weeds control in maize crop during the three kharif seasons of 2013 to 2015. The dominant weeds infested the experimental plots were crow footgrass{Dactyloctenium aegyptium (L.) Willd.}; large crabgrass, Digitaria sanguinalis (L.) Scop; barnyard grass, Echinochloa crus-galli (L.) Beauv.; Digera arvensis Forsk. and Horse purslane(Trianthema portulacastrum L.). All the three HPPD herbicides showed good crop safety and among them, for grass weed control, mesotrione 120 g ha-1 applied alone was inferior to topramezone 50 g ha-1 and tembotrione 120 g ha-1 applications. However, reduced doses of the HPPD herbicide (mesotrione 90 g or topramezone 37.5 g or tembotrione 90 g ha-1) with atrazine 900 g ha-1 as post-emergent tank-mixture gave better weed control and maize yield than their solo applications. The uncontrolled weed competition reduced the maize yields by 31.5 to 68.5%. Overall, topramezone + atrazine provided comparable or superior control of annual grass and broad-leaf weeds than mesotrione + atrazine or tembotrione + atrazine. Post applied (15-18 days after sowing) atrazine 1000 g ha-1 was better to pre-emergence atrazine in weed control and producing maize yield. In another field study, replacement of maize with puddle rice completely reduced the Johnsongrass {Sorghum halepense (L.) Pers.} density and therefore, in areas having its infestation, rice can be an alternative to contain its problem. The synergistic interactions between HPPD-inhibiting herbicides, and atrazine, were also observed against three grass weeds in pot experimentation as higher weed control achieved than what was expected from Colby's equation. The results show that tank-mixture of topramezone or tembotrione with atrazine can be effectively used for diverse weed flora control in maize.