Quantification of the effects of bacterial blight disease on rice crop growth and grain yield

Experimental and simulation studies on the effect of epidemics of bacterial leaf blight in rice showed that at high levels of nitrogen fertilization, crop damage in terms of reduction in grain yield and total biomass was greater with epidemics initiated at early and late tillering compared to epidemics initiated at flag leaf appearance. Higher levels of N application favoured the production of larger amounts of green leaf area and disease epidemics. A disease onset at early and late tillering caused more damage than an infection at flag leaf appearance. In a second experiment, the onset time of disease was fixed but duration of the epidemics was varied with three levels of bacterial blight disease epidemics at different N levels. The results on total dry matter production and grain yield indicated stronger reductions in the plots where the disease was maintained throughout crop growth followed by inoculations up to late and early tillering. These differences were more pronounced at higher levels of N application.