Atrazine For Weed Control Research Articles

Effect of Post-Emergence Application of Nicosulfuron in Mixture with Atrazine for Weed Control in Sweet Sorghum

The objective of this work was to evaluate if different rate of a nicosulfuron and atrazine mixture applied post-emergence to effectively control weeds in sweet sorghum without interfering in the initial growth and gas exchanges of the crop. The genotypes BRS 506, BRS 511, and SF 15 were subjected to weed management with atrazine (2500 g a.i. ha−1) mixed with six different doses of nicosulfuron (10, 20, 30, 40, 50, 60 g a.i. ha−1). The herbicide mixtures were applied 12 days after sowing. At 7, 14, 21, and 28 days after application (DAA), phytotoxicity evaluations were performed in sorghum genotypes and weed control efficiency was evaluated. Initial growth (plant height, stalk diameter, leaf area, and number of leaves), gas exchanges, and relative chlorophyll index (a and b) were determined 7 DAA. The production of total fresh biomass, total soluble solids and ethanol yield were carried out at the end of the culture cycle. The mixture with doses higher than 40 g a.i. ha−1 of nicosulfuron with atrazine caused greater phytotoxicity in sweet sorghum and better weed control. Gradual increase in nicosulfuron reduced photosynthesis, transpiration, and initial growth of sorghum crop. The weed control did not interfere with production of fresh biomass, total soluble solids content and ethanol production, but showed different response in tested genotypes (BRS 511 > BRS 506 > SF 15). Thus, within the dose range evaluated, the mixture of 30 g a.i. ha−1 of nicosulfuron with atrazine was found effective in controlling weeds in sweet sorghum plantations without causing significant damage to the crop.

Tolpyralate Applied Alone and With Atrazine for Weed Control in Corn

Tolpyralate, an HPPD (4-hydroxyphenyl-pyruvate dioxygenase) inhibitor, is a relatively new herbicide for weed control in corn. Field studies were conducted in 2015 and 2016 to evaluate the effective dose of tolpyralate applied alone or mixed with atrazine for weed control in corn. The treatments included seven rates (0, 5, 20, 29, 40, 50 and 100 g ai ha-1) of tolpyralate applied alone or mixed with a constant rate (560 g ai ha-1) of atrazine. The evaluated weed species were common waterhemp (Amaranthus rudis Sauer), common lambsquarters (Chenopodium album L.), velvetleaf (Abutilon theophrasti Medik), henbit (Lamium amplexicaule L.) and green foxtail (Setaria viridis L.). Overall, POST-application of tolpyralate resulted in 58-94% visual weed control when applied alone; whereas, addition of atrazine provided 71-100% control of same species. Calculated dose of 19-31 g ai ha-1 (ED90) of tolpyralate applied alone provided 90% visual control of waterhemp, lambsquaters, henbit, and velvetleaf. Whereas, addition of atrazine resulted in significantly lower dose of 11-17 g ai ha-1 for the same level of control, suggesting synergy between the two herbicides.

Isolation and characterization of atrazine-degrading Arthrobacter sp. strains from Argentine agricultural soils

Three bacterial strains capable of degrading atrazine were isolated from Manfredi soils (Argentine) using enrichment culture techniques. These soils were used to grow corn and were treated with atrazine for weed control during 3 years. The strains were nonmotile Gram-positive bacilli which formed cleared zones on atrazine solid medium, and the 16S rDNA sequences indicated that they were Arthrobacter sp. strains. The atrazine-degrading activity of the isolates was characterized by the ability to grow with atrazine as the sole nitrogen source, the concomitant herbicide disappearance, and the chloride release. The atrazine-degrader strain Pseudomonas sp. ADP was used for comparative purposes. According to the results, all of the isolates used atrazine as sole source of nitrogen, and sucrose and sodium citrate as the carbon sources for growth. HPLC analyses confirmed herbicide clearance. PCR analysis revealed the presence of the atrazine catabolic genes trzN, atzB, and atzC. The results of this work lead to a better understanding of microbial degradation activity in order to consider the potential application of the isolated strains in bioremediation of atrazine-polluted agricultural soils in Argentina.

Warm‐season Grass Establishment with Atrazine1

AbstractWeed competition is a limiting factor in warm‐season grass establishment often delaying the first forage harvest 2 or 3 years. Weed control with herbicides could reduce this competition resulting in more rapid grass establishment. Field experiments were conducted to evaluate the effect of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] on weed control, warm‐season grass establishment, and forage yield during the seeding and following year.Several warm‐season grass species were spring seeded at locations having distinctly different soils. The soils involved were a Butler silty clay loam (Abruptic Argiaquoll) containing 3.8% organic matter and a pH of 5.2, a Crofton silty clay loam (Typic Ustorthent) containing 2.1% organic matter with a pH of 7.2 and a Nora silty clay loam (Udic Haplustoll) containing 2.8% organic matter and pH 5.8. Atrazine at various rates was applied preemergence shortly after grass seeding and at one site it was atso applied the preceding fall. Weed control, grass establishment, and forage yield were measured the year of seeding and the following year.Uncontrolled weeds during the year of seeding reduced stands and 1st year forage yields of big bluestem (Andropogon gerardi Vitman), indiangrass [Sorghastrum nutans (L.) Nash], sand lovegrass [Eragrostis trichodes (Nutt.) Wood], sideoats grama [Bouteloua curtipendula (Michx.) Torr.], and switchgrass (Panicum virgatum L.). Big bluestem and switchgrass tolerated preemergence atrazine applications of 3.4 kg/ha on the Butler soil. Big bluestem was less tolerant of atrazine than switchgrass on the Crofton soil. Some atrazine tolerance was present in indiangrass but not in sand lovegrass and sideoats grama. Seeding year forage yields of big bluestem and switchgrass were significantly increased by atrazine. Weed control during the seeding year sometimes resulted in higher forage yields the following year. Big bluestem and switchgrass can he readily established and produce substantial forage yields the year of seeding by using atrazine for weed control. This would make these grasses more attractive to farmers and ranchers.

Trifluralin and atrazine for weed control in lupin seed crops

Trifluralin and atrazine for weed control in lupin seed crops