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Effect of Doses, Application Dates, Adjuvants and Zinc Sulfate on Bromoxynil + Terbuthylazine + NicosulfuronWeed Control Efficacy and Maize Grain Yield in Mid-West Poland
Effect of Zinc Sulfate and Adjuvants on the Physicochemical Properties and Efficacy of Bromoxynil with Terbythylazine and Nicosulfuron Mixtures Against Echinochloa crus-galli L.
The study aimed to evaluate the effects of methyl esters adjuvant, pH reducer, and zinc sulfate on the physicochemical properties (contact angle, surface tension) of a spray liquid and a bromoxynil + terbuthylazine + nicosulfuron mixture’s efficacy. Cockspur (Echinochloa crus-galli L.) was used as the test plant. The placement of any adjuvant in the spray liquid affected the reduction in contact angle, with zinc sulfate reducing it from 75.9 to 66.3°, methyl esters adjuvant from 61.8 to 47.1°, pH reducer from 58.3 to 47.0°, zinc sulfate + methyl esters adjuvant from 64.9 to 58.4°, and zinc sulfate + pH reducer from 57.1 to 44.6°. A decrease in contact angle was found with a reduction in herbicide doses, from 65.6 to 59.0°. The highest pH of the spray liquid with herbicides was found when the methyl esters adjuvant was added to the liquid (6.82–7.17), followed by 6.43–6.80 when zinc sulfate was added, and 6.05–6.30 for zinc sulfate with methyl esters adjuvant. The inclusion of adjuvant pH reducer very strongly reduced the liquid reaction to 3.28–3.60, and it was reduced to 2.76–2.90 in the presence of zinc sulfate. Bromoxynil + terbuthylazine + nicosulfuron mixtures applied with methyl esters adjuvant and zinc sulfate with pH reducer showed the highest efficacy (85–98% and 82–96%), and the efficacy was 64–81% when methyl esters adjuvant with zinc sulfate were used. The effect of the herbicide mixture with only zinc sulfate was noticeably weaker (40–81%), and it was very weak (13–43%) in the presence of adjuvant pH reducer only. On the basis of the ED50 values, the most favorable mixtures were those containing methyl esters adjuvant, methyl esters adjuvant + zinc sulfate and pH reducer + zinc sulfate in addition to the herbicides. Research has indicated that zinc sulfate could be used as an adjuvant, and will support not only the action of herbicides, but also the development of maize plants.
Impact of Multifunctional Adjuvants on Efficacy of Sulfonylurea Herbicide Applied in Maize (Zea mays L.)
To reduce the cost of intensive herbicide application and environment pollution and enhance biological effectiveness, effective multifunction adjuvants should be used. A field study was conducted in 2017–2019 in midwestern Poland in order to assess the effects of new adjuvant formulations on the activity of herbicides. Treatments included the herbicide nicosulfuron at recommended (40 g ha−1) and reduced rates (28 g ha−1) alone and with the addition of tested MSO 1, MSO 2, and MSO 3 (differing in the type and amount of surfactants), as well as standard (MSO 4 and NIS) adjuvants. Nicosulfuron was applied once during the 3–5 leaf stage of maize. Results indicate that nicosulfuron with the tested adjuvants provided satisfactory weed control equivalent to that provided by standard MSO 4 and better than that provided by NIS. Nicosulfuron applied with the tested adjuvants led to a similar grain yield of maize as that achieved with standard adjuvant treatments and much higher than that measured in untreated crops.