Protective, curative and eradicative activities of fungicides against grapevine rust

Abstract

The protective, eradicative and curative activities of the fungicides azoxystrobin, tebuconazole, pyraclostrobin+metiram, and ciproconazole against grapevine rust, were determined in greenhouse. To evaluate the protective activity, leaves of potted ´Niagara´ (Vitis labrusca) vines were artificially inoculated with an urediniospore suspension of Phakopsora euvitis four, eight or forteen days after fungicidal spray; and to evaluate the curative and eradicative activities, leaves were sprayed with fungicides two, four or eight days after inoculation. Disease severity was assessed 14 days after each inoculation. All tested fungicides present excellent preventive activity against grapevine rust; however, tebuconazole and ciproconazole provide better curative activity than azoxystrobin and pyraclostrobin+metiram. It was observed also that all tested fungicides significantly reduced the germination of urediniospore produced on sprayed leaves.

Comparative epidemiology of grapevine and soybean rusts

“…Asian grapevine leaf rust symptoms and spore production started 8 days post inoculation at 25 ºC, on average. The Asian grapevine leaf rust latent period under equivalent inoculation conditions observed in other reports was similar to our data (Angelotti et al, 2014;Alves, 2015). Incubation and latent periods of Asian soybean rust are in general 6 to 10 days post inoculation at 22 ºC (Pivonia & Yang, 2006;Alves et al, 2007;Danelli & Reis, 2016).…”

“…Monocyclic components can be used to compare pathosystems at an individual level, and the variables can be: (i) incubation period, corresponding to the time interval between pathogen inoculation and the appearance of symptoms; (ii) latent period, corresponding to the time interval between pathogen inoculation and the urediniospore production; (iii) infectious period, corresponding to the time interval of urediniospore production; (iv) number of lesions; (v) average size of lesion; and (vi) final biomass of each pathogen. Data from the literature can be useful for the analyses of comparative epidemiology; however, in the case of rusts caused by Phakopsora, the diversity of experimental conditions in several published reports and a lack of evaluation of certain monocyclic components do not allow this approach based only on literature information (Berger et al, 1995;Alves et al, 2007;Bonde et al, 2007;Angelotti et al, 2014). On the other hand, from the literature it is possible to obtain the weather conditions that are most favourable for disease development.…”

“…meliosmae-myrianthae urediniospore germination and the appearance of symptoms of Asian grapevine leaf rust with wetness periods longer than 12 h (Angelotti et al, 2014;Alves, 2015;Navarro et al, 2015). The ideal temperature for the appearance of bean rust symptoms ranged from 16 to 21 °C (Bassanezi et al, 1997); the ideal leaf wetness period was longer than 10 h (Coelho et al, 2003).…”

“…In grapevine 'Niagara Rosada' inoculated with P. meliosmae-myrianthae, the latent period ranged from 7 to 13 days; the temperature response curve of the latent period presented a typical asymmetric U-shape (Alves, 2015), as also observed for other rusts in other cultures (Zadoks & Schein, 1979;Kolnaar & van den Bosch, 2001;Hernandez-Nopsa & Pfender, 2014). When grapevine plants inoculated with P. meliosmae-myrianthae were incubated at minimum (15 °C), optimal (25 °C), and maximum (30 °C) temperature for disease development, the latent periods were 13 to 15, 6 to 7, and 6 to 9 days, respectively (Angelotti et al, 2014;Alves, 2015). A tissue collapse expressed as foliar necrosis between lesions and defoliation was observed when plants were incubated at 30 °C (Alves, 2015).…”

“…Although there are several reports of the monocyclic components of soybean and grapevine rust in the literature, no comparative epidemiological analysis has verified whether P. meliosmae-myrianthae is classified as a pathogen adapted to the tropics. Data from monocyclic components are fragmented in the literature and in general are not comparable between pathosystems, either because the methodology of the experiments was variable or because data acquisition methods differed (Berger et al, 1995;Alves et al, 2007;Bonde et al, 2007;Angelotti et al, 2014).…”