Estudo da sistemicidade e tenacidade de epoxiconazol, piraclostrobina e fluxapiroxade em plantas de soja e videira

Abstract

Study of the systemicity and rainfastness of epoxiconazole, pyraclostrobin and fluxapyroxad in plants of soybean and vine. The chemical control is one of the measures most used in the management of plant diseases, being essential in many agricultural pathosystems. Therefore, understanding the dynamics of the interactions between products and plants has great practical importance in providing knowledge that can support better the control strategies. The work has aimed to study the rainfastness and systemicity of the fungicides epoxiconazole, pyraclostrobin and fluxapyroxad in soybean and vine plants. The rainfall was simulated in different intensities and intervals after application in order to assess the rainfastness of the products.The pathogens, Phakopsora pachyrhizi and Phakopsora euvitis were inoculated and the severity and the area under the disease progress curve were assessed. For the uptake and translocation studies, it was used the radiolabeled molecules, 14 C-epoxiconazole, 14 Cpyraclostrobin and 14 C-fluxapyroxad, which were diluted with their respective commercial formulations. The parameters were assessed at 3, 9, 24, 48 and 72 hours after application (HAA). In particular for the fluxapyroxad were assessed the effects of its association with adjuvant and potassium phosphite on soybean plants, and their absorption and translocation in old and new vine leaves. Overall, the fungicides efficiency were boosted with the increasing interval between the application and the rainfall simulation. The addition of adjuvant improved the rainfastness of fluxapyroxad and the phosphite did not have the same effect.The systemicity on soybeans was high for the epoxiconazole, intermediate for fluxapyroxad and low for pyraclostrobin. In vine, pyraclostrobin was more absorbed, followed by epoxiconazole and fluxapyroxad. The fungicides epoxiconazole and fluxapyroxad translocated mainly acropetally and pyraclostrobin did not show translocation to long distances. The addition of adjuvant to fluxapyroxad has promoted greater and more rapid uptake and translocation on soybean plants, while potassium phosphite had antagonistic effect, which resulted in 53% reduction in uptake. There was no difference in the absorption and translocation of fluxapyroxad in old and new vine leaves. Nevertheless, the redistribution was higher in young leaves. The fluxapyroxad proved to be a fungicide with protective and curative potential. Protective because large amount of product (>65%) remains outside of the soy and vine leaves up to 72 HAA and curative because it showed an increased absorption over the time, which means that there is a continuous release of the product into the leaves. The soybean leaflets absorbed more the three fungicides than the vine leaves. The translocation to long distances in both crops were low (<1%) for all evaluated fungicides. The translocation of epoxiconazole and fluxapyroxad increases with the course of time on soybean plants and not in nursery trees of vine and the pyraclostrobin has limited and constant translo...

Chemical control of dieback and mango malformation in a semiarid region

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Influência do tratamento de sementes e da disponibilidade de água na arquitetura e no crescimento de plântulas de soja

“…6%) que foi significativamente inferior ao tratamento T1 (100,0%), os demais tratamentos obtiveram valores maiores que o tratamento T1 para o IPM, com os tratamentos T6 (110,7%) e T5 (110,5%) com os maiores valores sem DAS em condição sem estresse hídrico pode estar relacionado com suas características de sistemicidade intermediária e de translocação rápida no sentido acropetal, com um aumento desta translocação ao longo das horas para a cultura da soja(SANTOS, 2016). Estas características podem ter favorecido com que as plântulas apresentassem os efeitos positivos do Fluxapiroxade somente no experimento aos 12 DAS e em condição sem estresse hídrico.…”