Uredospore Germination and Development of Some Cereal Rusts from South‐central Chile at Constant Temperatures

Abstract

The minimum and maximum temperatures for germination of uredospores of Puccinia striiformis, P. recondite, P. coronata and P.gramnis isolates from south‐central Chile were 0°C and 26°C, 0°C and 32°C, 8°C and 30°C, and 4°C and 34°C, respectively, whereas the shortest latent period was 8.5 days for P. struformis at 20°C, 5 days for P. recondite at 26°C, 5.5 days for P. coronata at temperatures, reaching the minimum and maximum threshold temperatures at 0.006°C and 23°C for P. strüformis, 0.31°C for P. recondita, 2.87°C and 30°C for P. coronata, and 1.72°C and 32°C for P. graminis. rspectively. The cardinal temperatures give no explanation as to the observed sequential appearance of these rusts during the growing season. Other phenomena like the systemic mycelial growth of P.striiformis might be involved here. At temperatures between 19°C and 22°C, the average daily increase of the area of sporulation of P.striiformis in wheat leaves varied between 9.05 and 22.48 mm2/infection site. This variation was due to substrate (plant) history and environmental factors.

The role of temperature and rainfall in the epidemiology of Puccinia striiformis f.sp. tritici in the summer rainfall area of eastern Australia

“…1950;Tollenaar & Houston, 1966;Osman-Ghani & Manners. 1983;Tollenaar, 1985). In all of these studies uredospores were germinated on artificial media such as water agar for periods up to 48 h. Sharp (1966) examined infection of seedlings by an isolate of P. striiformis from the USA at constant temperatures, and found the optimum and maximum temperatures to be 7 C and 15 C, respectively.…”

Over-summering of wheat stripe rust (Puccinia striiformis f.sp. tritici) in the California Central valley: A case study

“…However, an ALTQ10 of 0.829 was obtained, pointing to a substantial underestimation of the lethal impact of high temperatures on stripe rust. This can be mainly attributed to the fact that with the present method of calculation the harmful effect of daily temperatures between 25 and 30 ºC (Tollenaar and Houston, 1967;Tollenaar, 1985;Dennis, 1987) goes unaccounted for. The explanation for this omission is that detailed information to quantify the lethal impact of temperatures between 25 and 30 ºC on stripe rust is lacking and therefore, although incorrectly, this effect has been considered here to be non-existent.…”

Wind-dispersed diseases

“…The smaller growth rates at low temperature are partly compensated by a longer duration of colony growth (Eckhardt et al, 1984a). (-♦-Tollenaar, 1985;--Zadoks, 1961), Puccinia triticina on wheat (-♦-Tollenaar, 1985;--Tomerlin et al, 1983;--Johnson, 1980;-∆-Eversmeyer et al, 1980), Puccinia graminis f.sp. tritici on wheat (-♦-Tollenaar, 1985) and Blumeria graminis f.sp.…”