Epidemiology and Chemical Control of Soybean Rust in Southern Africa

Abstract

Phakopsora pachyrhizi was discovered on soybeans in Uganda in 1996. This was the initial confirmation of the pathogen on soybeans in Africa, although there had been earlier unsubstantiated listings on other legumes. Thereafter, it was wind-dispersed southward to Rwanda, Zimbabwe, and Zambia in February 1998, where it severely damaged commercial plantings. It also devastated small-scale fields in eastern Nigeria at about this time. Rust continued its southward movement to southern Mozambique in early 2000, and into eastern South Africa in March 2001. By early 2003, substantial losses were being reported from western Cameroon. Scientists in Zimbabwe and South Africa have coordinated their research to combat the pathogen and have developed a strategy based on the effective, economical use of fungicides and the development of resistant germ plasm. The chemical and spraying recommendations resulting from field studies are discussed in relation to their practicalities, and a preliminary analysis of the meteorological data recorded will show the fundamental factors that influence the development of an epidemic.

Droplet spectrum and fungicide efficiency in the control of Asian soybean rust (Phakopsora pachyrhizi Syd. & P. Syd.)

“…When comparing the number of lesions and uredia.cm 2 in untreated and treated leaflets, these last were four and nine-fold higher, respectively. In fact, the efficiency of fungicides has also been demonstrated by other authors as Levy (2005), and there is a positive association between uredia and lesions.cm 2 (Garcés-Fiallos & Reis, 2012). The use of fungicides in soybean leaflets promotes a higher leaf area duration (Garcés-Fiallos & Forcelini, 2011b) and an increasing in grain yield (Cunha & Ruas, 2006;Cunha et al, 2008;Henry, Johnson & Wise, 2011;Levy, 2005).…”

Pathogenic Variation of South American <i>Phakopsora pachyrhizi</i> Populations Isolated from Soybeans from 2010 to 2015

“…One of the most damaging diseases of soybeans is soybean rust caused by Phakopsora pachyrhizi H. Sydow & P. Sydow (Hartman et al 2011, Miles et al 2003, Pennisi 2010. Soybean rust can result in a 10%-80% reduction in yield or losses of over 80%, particularly when the disease develops under preferable environmental conditions for P. pachyrhizi (Hartman et al 2005, Levy 2005, Li et al 2010, Pennisi 2010, Rosa et al 2015, Yorinori et al 2005. Since the first outbreak of soybean rust caused by P. pachyrhizi in Paraguay and Brazil in 2001 and in Argentina in 2003 (Ivancovich 2005, Rossi 2003, Yorinori et al 2005, it has rapidly spread to most of the soybean fields throughout South America, and has continuously impacted soybean production in the region, resulting in tremendous economic losses.…”

A FERRUGEM ASIÁTICA DA SOJA CAUSADA POR Phakopsora pachyrhizi Sydow e Sydow

“…Estudos realizados mostram também que, em condições severas de epidemia, são necessárias de três a cinco aplicações em intervalos de 10 dias (Sinclair e Hartman, 1995). Já (Levy, 2005) com relação a momento de aplicação, conduzindo ensaios na África, mostraram que três ou mais aplicações foram necessárias para manter o potencial produtivo, enquanto que uma ou duas aplicações foram insuficientes para controlar a doença.…”