Number of pustules of garlic rust under different temperatures and leaf wetness

Abstract

Puccinia porri is an etiological agent of garlic rust. The disease symptoms are characterized by leaf lesions that initially appear as whitish spots. With the disruption of the leaf cuticle, yelloworange uredospores are exposed. These signs are commonly known as pustules. Bulb production is affected by the reduction of photosynthetically active leaf area. The decrease in production is most pronounced when the attack occurs before bulb formation. The objective of this work was to quantify the latency periods of garlic rust and the number of pustules formed under the influence of temperature (10, 15, 20 and 25ºC) and leaf wetness period (6, 12, 18 and 24h). The latent period for this pathosystem varied between 10 and 12 days when the plants were subjected to temperatures of 10, 15 and 20°C after inoculation. The number of rust pustules was higher in garlic plants subjected to a temperature of 15°C. However, there were also a significant number of lesions at temperatures of 10ºC, especially when the leaf wetness period was 24 hours. At temperatures above 20°C, the number of pustules was less expressive. The results are important to perform fungicide efficacy tests in optimal conditions for disease progression and epidemiological studies.