The effect of temperature and light intensity on growth and sporulation of Puccinia striiformis on wheat

Urediniospore production by Puccinia striiformis on wheat per unit leaf area infected was much lower at low light intensities than at high light intensities. The number of pustules per unit area of infected leaf and the daily sporulation rate per pustule increased linearly with increasing light over the range 10–50 W/m². Increasing temperature between 7 and 20°C shortened latent period and reduced the longevity of sporulating leaves. Colonization rate and the frequency of pustules per unit area of infected leaf increased between 7 and 15°C but declined markedly at 20°C. Spore production reached its peak earlier and declined more rapidly with increasing temperature between 7 and 15°C. this decline being less marked in the highly susceptible cultivar Maris Beacon than in the more resistant Maris Nimrod and Maris Huntsman.