Review of strobilurin fungicide chemicals

Strobilurins are natural products isolated and identified from specific fungi. Natural strobilurins were named in the order of their discovery as strobilurin-A followed by strobilurin-B, C, D etc. Their discovery opened the door for new chemistry of synthetic fungicides. Applying Quantitative Structural Activity Relationship (QSAR) on the structures of the natural strobilurins, many pesticide companies were able to discover many synthetic analogues that are more efficacious and more stable fungicides. At present there are about eight synthetic strobilurins in the fungicides worldwide market. Some of these products are worldwide registered for use as agrochemical and some are in the process of registration. This class of fungicides is relatively new, as crop protection products and information about them is still fairly scarce. In this review, syntheses and chemistry of natural and synthetic strobilurins are discussed. Also, the mode of action, efficacy, biotic/abiotic degradation, analytical methods, and agricultural uses are discussed.     

Persistence of repeated triadimefon application and its impact on soil microbial functional diversity

The effects of repeated applications of the fungicide triadimefon in agricultural soil on the microbial functional diversity of the soil and on the persistence of the fungicide in the soil were investigated under laboratory conditions. The degradation half-lives of triadimefon at the recommended dosage, simulated by a first-order kinetic model, were 23.90, 22.95, and 21.52 days for the first, second, and third applications, respectively. Throughout this study, no significant inhibition of the Shannon-Wiener index (H′) was observed. However, the Simpson index (1/D) and the McIntosh index (U) were obviously reduced (p ≤ 0.05) during the initial 3 days after the first triadimefon application and thereafter, gradually recovered to or exceeded the level of the control soil. A similar trend in variation but with a faster recovery in the 1/D and U was observed after the second and third triadimefon applications, respectively. Taken together, the above results indicate that the repeated application of triadimefon enhanced the degradation rate of the fungicide and the recovery rate of the soil microbial functional diversity. It is concluded that repeated triadimefon applications in soil have a transient or temporary inhibitory effect on soil microbial communities.     

Effect of some preparates on soil microflora on the basis of soil bioassay

Abstract

Trials for control of soil‐borne plant pathogen fungi with biological and chemical fungicide preparates have been carried out in our Biological Control Laboratory for more than 10 years. During all these experiments soil bioassay was always carried out in order to observe the soil microflora. Here we mention one trial which confirms the general opinion that chemical treatments significantly change the soil microflora. The tested biological fungicide did not cause such changes.     

Arachis hypogaea derived activated carbon steered remediation of Benzimidazole based fungicide adsorbed soils

Sorption characteristics of the Benzimidazole fungicide Carbendazim were assessed in seven different soils using batch equilibrium method and analysed by UV-Vis spectrophotometer. The values of adsorption co-efficient K_d ranged from 14.3 to 39.8?µg/mL depending upon unique physiochemical properties of soils. Negative values for Gibbs free energy (ΔG) proposed an exothermic and low interaction between Carbendazim and soil samples leading to physiosorption. Statistical analysis showed a negative correlation of soil pH and K_d (R²= ?0.80) and a positive correlation with organic matter (R^2?=?0.77). Activated carbon prepared from Arachis hypogaea (peanut shells) by acid activation for Carbendazim removal from soils was characterised by FTIR spectrometry, indicating the change in functional groups. The highest percentage removal observed was 70% in 5?ppm initial Carbendazim concentration while 65% in 7.5?ppm concentration. This method can be implied in agricultural soils as an efficient and cheap technique for removing the hazardous pesticides from the environment.