Residual effect of atrazine on field-grown dry beans and sunflower

Abstract

The applicability of fixed recropping intervals for crops that are sensitive to atrazine (2-chloro-4-ethylamino-6-isopropylamino-1 ,3,5-s-triazine) was assessed. Atrazine carry-over was monitored 12 and 24 months after its application at six different rates to maize (Zea mays L.) grown in eight trials at six sites. The rotational test species were dry beans (Phaseo/us vulgaris L. cv. Teebus) and sunflower (He/ianthus annuus L. cv. SO 222). Yield reductions indicated the carry-over of phytotoxic atrazine residues. At 12 months after treatment dry bean yield was significantly reduced at one site and sunflower yield at six, on plots previously treated with the atrazine rates recommended for maize. During the next season significant yield reductions (dry beans 38%; sunflower 29%) occurred only on the single montmorillonite soil (pH 7.8). The relatively high tolerance of the dry bean cultivar in most soils at the first assessment is not reflected in the single recropping period of 18 months that is currently recommended for both species. Current recropping intervals for sensitive crops could be refined by assigning flexible intervals that are based on the herbicide's expected dissipation rate in a particular soil, as well as on the tolerance of the follow-up crop.Die toepaslikheid van rigiede wagperiodes wat vir gewassoorte met lae verdraagsaamheid teenoor atrasien (2-chloor-4-etielamino-6-isopropielamino-1 ,3,5-s-triasien) aanbeveel word, is ondersoek. Oordraging van atrasien is op 12 en 24 maande na toediening daarvan in mielies (Zea mays L.), in agt proewe by ses lokaliteite, gemonitor deur die opbrengs van twee opvolggewasse, droebone (Phaseo/us vulgaris L. cv. Teebus) en sonneblom (He/ianthus annuus L. cv. SO 222), te bepaal. Opbrengsverliese by hierdie gewasse het oordraging van atrasien aangedui. Twaalf maande na toediening van die aanbevole atrasienpeile in mielies is droebone in daardie persele betekenisvol beskadig by een lokaliteit, en sonneblom by ses. In die daaropvolgende seisoen is die opbrengs van be ide gewasse alleenlik verlaag (droebone 38%; sonneblom 29%) op die enigste montmorillonietgrond (pH 7.8). Die relatief hoe verdraagsaamheid wat die droebooncultivar by die eerste monitering daarvan vertoon het, word nie in die wagperiode (18 maande) wat tans vir beide gewasse gestel word, weerspieel nie. Die rigiede wagperiodes wat tans geld, kan verfyn word deur die gebruik van buigsame intervalle wat gebaseer is op die verwagte tempo van verlies van atrasien in 'n bepaalde grond, asook op die verdraagsaamheid van die opvolggewas.

The effect of Herbicides on Residual Effects of Atrazine under Conservation Agriculture

“…Atrazine had the lowest yield of 0.9t/ha (Figure 4). When atrazine is applied alone it tends to have a residual effect on the successive crop (Reinhardt, 1995). A combination of three herbicides had the highest yield of 1.2t/ha but no significant differences were observed between a combination of three herbicides and control plot.…”

“…Atrazine alone had the least pod length of 15.77cm (Figure 2). This is because when atrazine is applied alone it tends to have more residual effect on the crop (Reinhardt, 1995). Moreover, no significant effect (p>0.05) between control and a combination of three herbicides was observed.…”

Atrazine, mesosulfuron‐methyl, and topramezone persistence in North Carolina soils

“…In contrast, Pawlak et al (1987) observed up to 38% soybean injury 1 yr after atrazine application in a fine-loamy soil under reduced tillage in Michigan. Globally, cooler and drier soils have been shown to increase atrazine persistence and damage to subsequent crops (Frank et al, 1983;Moyer & Blackshaw, 1993;Reinhardt, 1995). Reinhardt et al (1990) recommended that guidelines for atrazine plant-back intervals be redefined based on soil properties, but more data are needed to make appropriate recommendations for many soil types.…”

Evaluation of the potential of jack bean [Canavalia ensiformis (L.) DC.] and velvet bean [Mucuna pruriens (L.) DC.] aqueous extracts as post-emergence bio-herbicides for weed control in maize (Zea mays L.)

“…The use of atrazine in maize (Zea mays L.)-legume rotations in Zimbabwe is likely to increase in CA since research done in several environments demonstrated that 1.8 kg ha -1 active ingredient (a.i) of atrazine that is recommended in maize does not affect soya bean (Glycine max L.) grown 12 months following herbicide application in the same field (Muoni et al, 2014). This is contrary to conventional tillage where broad-leaved crops susceptible to atrazine can only be safely grown after 18 months from the date of atrazine application (Reinhardt, 1995). Keeping in view the potential of allelopathy in weed management, studies were carried out to evaluate the efficacy of postemergence applications of jack bean and velvet bean leaf, stem, and root aqueous extracts on weed control efficacy as single treatments or in mixture with reduced dosage rates of atrazine.…”