An Overview of the Epidemiology of Phakopsora pachyrhizi in the State of Mato Grosso, Brazil

Abstract

This review seeks to expand the knowledge about the epidemiology of Asian sybean rust in the state of Mato Grosso and contribute to ensuring the economic sustainability of soybean crop. It is discussed the Phakopsora pachyrhizi potential of dispersal from Asia to South America and finally to Mato Grosso state. The origin of the Asian soybean rust inoculum within Mato Grosso is addressed by the survival in volunteer and soybean weed plants (Pitelli, 2015) in other crops such as cotton. Data on the adverse environmental effect on the soybean plants survival are shown mainly the water deficit from June to August. Reports on the effect air temperature and mainly solar radiation on the mortality of airborne spores during their anemophilous spread on sunny days are also discussed. This increase of knowledge aims to make the soybean-free period more efficient by the knowledge on the soybean plants survival and on the fungus viability in the month of August. Due to the proximity of soybean farms, during the soybean-free period, in other states (Tocantins, Goiás, Rondônia, etc.) and in other neighbor countries we discuss the likelihood that inoculum in the state may also originate in out-of-state crops during the Mato Grosso soybean-free period.

Minimizing the Selection Pressure of Site-Specific Fungicides Towards Phakopsora pachyrhizi in Mato Grosso State: A Review

“…Only seeding time regulation is not the most effective strategy with the greatest impact to reduce P. pachyrhizi selection to site-specific fungicides, especially limited to December 31 th . Later sowing, February, evoking the escape principle, may be more effective as demonstrated in MT (Reis et al, 2021c). In other similar cases of resistance management, similar citations of legislation limiting the sowing period were not found in the literature (Gisi & Siertotzki, 2015;Schepers & Cooke, 2015).…”

“…Pathogenic fungi, such as P. pachyrhizi, with high reproductive potential are the most vulnerable to the resistance development. The proportion is one mutant for one million spores for the targe fungus: (i) in MT the cultivated area more than 10 million hectares; (ii) a soybean plant with high severity can produce 400 million spores (Reis et al, 2021); (iii) soybeans weed plants amid cotton crop attacked by rust, although ignored, also accelerate selection pressure (Reis et al, 2021c).…”

Lethality of Simulated UV and Solar Diffuse Radiations to Detached Urediniopores of Phakopsora pachyrhizi

“…Therefore, it has been questioned whether urediniospores. can maintain viability when detached from the host in this adverse weather period (Reis et al, 2021a(Reis et al, , 2021b.…”