Atrazine application

Du Preez, L.H., Solomon, K.R., and Carr, J. A. et al. (2005). Population structure of the African Clawed Frog (Xenopus laevis) in maize-growing areas with atrazine application versus non-maize-growing areas in South Africa. African Journal of Herpetology 54, 61-68. 

In terrestrial ecosystems, atrazine effectively inhibits photosynthesis in target weeds and can also affect certain sensitive crop plants. Atrazine metabolites are not as phytotoxic as the parent compound. Degradation is usually rapid, although atrazine can persist in soils for more than one growing season. Soil fauna may be adversely affected shortly after initial atrazine application at recommended levels, but long-term population effects on this group are considered negligible. 

No effect on yield when planted at least 8 weeks after atrazine application (Brecke et al. 1981)... 

At least 10-week interval required after atrazine application for successful germination (Brecke etal. 1981)... 

Yerkes et al. (1996) reported that although chlorophyll fluorescence measurements and C02 assimilation in resistant jimsonweed leaves were affected within 1 day of atrazine application, they returned to normal (at rates and levels equivalent to those in untreated leaves) within 5 days. Atrazine-resistant jimsonweed was cross-resistant to simazine, but was susceptible to prometryn, metribuzin, terbacil, and other herbicides. Chlorophyll fluorescence was unaffected in triazine-resistant pigweed, which showed cross-resistance to some triazines, moderate resistance to metribuzin and terbacil, and negative cross-resistance to bentazon and pyridate. 

Atrazine use in ecofallow usually is supplemented with other herbicides. For example, the first herbicide application to wheat stubble often uses glyphosate and 2,4-D or dicamba, with the atrazine application postponed until later in summer to coincide with the emergence of volunteer wheat, cheat, and downy brome. Atrazine can be applied with glyphosate, but antagonism with some atrazine formulations is associated with this tank mixture (Stahlman and Phillips, 1979 Wicks and Hanson, 1995) because of physical binding of inert components in the atrazine formulation with glyphosate (Ahmadi et al., 1980). Farmers know that if rainfall does not move atrazine off the wheat residue and into the soil, control of weeds, and volunteer wheat will be unsatisfactory. 

All simulations assume that 20 days have transpired since atrazine application and that /u = 0.0098 day (27, 39). ... 

The second soil, collected at a depth of 0-20 cm from the rice crop fields of the Ebro Delta area (Tarragona, Spain), where the pesticides are currently applied, was naturally contaminated with aged residues corresponding to the last atrazine application carried out 40 days before its sampling. Characteristics of this soil are shown in Table 12.2 (Soil 1), and more details are available in Durand, Forteza, and Barcelo (1989). 

At 2.5 mg atrazine/kg soil, equivalent to 2 kg/ha in the top 10 cm, field and laboratory studies demonstrated that mortality in arthropod coUembolids Onchiurus apuanicus) was 47% in 60 days however, fecundity was not affected at dose levels up to 5.0 mg/kg soil. It was concluded that atrazine applications at recommended treatment levels had negligible long-term population effects on sensitive species of soil fauna. At 5.0 or 8.0 kg atrazine/ha, all species of soil fauna tested, except some species of nematodes, were adversely affected. One month post-application, population reductions of 65-91% were recorded in protozoans, mites, various insect groups, and collem-bolids at 5.0 kg/ha after 4 months, populations were still depressed by 55-78%. At 8.0 kg atrazine/ha, soil faun populations... 

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