Effect of ammonium sulfate on the phytotoxicity, foliar uptake, and translocation of imazamethabenz in wild oat
Experiments were conducted in greenhouse, growth chamber, and laboratory conditions to determine the effect of ammonium sulfate [(NH4)2SO4] on the phytotoxicity, foliar uptake, and translocation of imazamethabenz on wild oat. Rates of (NH4)2SO4 up to 5% (w/v) applied with a greenhouse sprayer did not affect the phytotoxicity of the herbicide when the mix was applied at the one- to two-leaf stage. However, inclusion of 1 and 2% (NH4)2SO4 increased the phytotoxicity of the herbicide when the mix was sprayed at the two- to three-leaf, or the three- to four-leaf stage. At 10%, (NH4)2SO4 decreased the phytotoxicity of the sublethal dosage of the herbicide. When the herbicide was applied as individual drops to the growth chamber-grown plants, inclusion of (NH4)2SO4 at 1% did not affect phytotoxicity as measured by shoot growth. The presence of (NH4)2SO4 did not affect the amount of imazamethabenz retained by wild oat foliage, but it decreased [14C]imazamethabenz absorption, slightly antagonized acropetal translocation, and increased the basipetal translocation of [14C]imazamethabenz. It was concluded that application methods greatly modify the effect of (NH4)2SO4 on imazamethabenz phytotoxicity. Herbicide absorption and translocation as determined by one method do not necessarily represent the absorption and translocation patterns when different application methods are used. Absorption and translocation were not the factors that were responsible for the observed effect of (NH4)2SO4 on the herbicide phytotoxicity.
Jointed Effects of Mesosulfuron-Methyl + Iodosulfuron-Methyl-Sodium and Clodinafop-Propargyl Mixed with Adjuvants on wild Oat (Avena ludoviciana Durieu.)
Reduction of herbicide application rate is of major importance in IWM systems. Two dose-response experiments were conducted to determine the effects of mesosulfuron- methyl + iodosulfuron-methyl-sodium and clodinafop-propargyl mixture with or without adjuvants on wild oat (Avena ludoviciana Durieu.). Treatments included of six doses of mesosulfuron-methyl + iodosulfuron-methyl-sodium or clodinafop-propargyl alone and in six mixing ratios of 100:0%, 75:25%, 50:50%, 25:75%, 10:90% and 0:100% with adjuvants. Herbicides binary mixtures were evaluated by concentration addition (CA) model. Herbicides performances against wild oat were increased with adjuvants. ED50 values of the herbicides mixing were reduced significantly with Citowett, Frigate and Lower7 adjuvants. However, a significant increased in herbicides efficacy was observed. Dose-response curves of the two herbicides alone mixture showed that the lowest effects compared to two herbicides mixture with Citowett, Frigate and Lower7 adjuvants on wild oat. Among evaluated adjuvants, the addition of Citowett and Lower7 had the highest and the lowest effect, respectively. Keyword: Additive effect, adjuvant, binary mixture, dose-response, reduce herbicide. Abbreviations: Citowett, alkyl aryl polyglycol ether; Clodinafop, Propynyl (R)-2-(4-((5-chloro-3- fluoro-2-pyridinyl)oxy) phenoxy)propanoate; Concentration addition (CA); Effective dose to 50% of test plant (ED50); Frigate, ethoxylated long-chain fatty amines; Iodosulfuron-methyl-sodium, methyl 4-iodo-2-(3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)ureidosulfonyl)benzoate, sodium salt; Lower7, ureic nitrogen (N): 22.5% w/v (15% w/w), sulphuric anhydride (SO3): 60% w/v (40% w/w ); IWM, integrated weed management; Mesosulfuron-methyl, methyl 2- (((((4-methoxy-6- methyl-1,3,5-triazin-2yl) amino) carbonyl) amino) sulfonyl) benzoate; Wild oat, Avena ludoviciana Durieu. AVEST.
Genotypic diversity in field isolates of Babesia bovis from cattle with babesiosis after vaccination.
OBJECTIVE
To determine whether particular genotypes of Babesia bovis were common to field isolates obtained from cattle properties in Queensland where the B bovis vaccine had apparently failed.


DESIGN
A comparative study of polymerase chain reaction genotypes in different populations of B bovis.


PROCEDURE
Two polymerase chain reaction assays were applied to analyse DNA extracts of B bovis vaccine (K, T and Dixie strains) and 27 field isolates from 24 properties where disease outbreaks had occurred despite the use of the vaccine. To evaluate the stability of the genotypes identified, 11 of the field isolates were inoculated into experimental cattle that had either been previously vaccinated with T strain or not vaccinated.


RESULTS
No particular genotype of B bovis was responsible for the problems observed in previously vaccinated herds. None of the isolates had genotypes identical to the vaccine strains used. No geographic trends among the genotypes were observed. Isolates that originated from the same property also had different genotypes. Blood passage of the 11 field isolates in either previously vaccinated or nonvaccinated cattle did not alter the original genotype.


CONCLUSION
No particular genotypes identified by the Bv80 and BvVA1 polymerase chain reaction assays could be associated with vaccine failures.