Disease Development and Symptom Expression of Xanthomonas axonopodis pv. citri in Various Citrus Plant Tissues

Abstract

Experimental inoculations of Xanthomonas axonopodis pv. citri in different tissues of Tahiti lime and Pineapple sweet orange were conducted monthly under natural conditions on Réunion Island. The interactions between a set of environmental and epidemic variables associated with disease expression and 184 different factor combinations were investigated to determine the parameters needed to explain Asiatic citrus canker (ACC) disease expression. Area under the disease progress curve (AUDPC), inoculation date (Id), fruit and leaf age ratings (FAR and LAR), and number of days during the first 2 weeks postinoculation for which the temperature was less than 14 degrees C (T(min)) or more than 28 degrees C (T(max)) were retained by principal component analysis and canonical correlation analysis as the most meaningful epidemic and environmental variables, respectively. AUDPC as the strongest dependent variable and combinations of the environmental variables as independent variables were used in multiple regression analyses. Tissue age rating at the time of infection was a good predictor for disease resulting from spray inoculation on fruits and leaves and also on fruits following a wound inoculation. Temperature, as expressed by T(min) or T(max), was also a significant factor in determining disease development described by AUDPC. Mature green stems were highly susceptible after wounding, similarly to leaves, but buds and leaf scars expressed the lowest susceptibility. These variations in disease expression according to the tissues will have different impacts on ACC epidemiology.

Comparative ultrastructure of nonwounded Mexican lime and Yuzu leaves infected with the citrus canker bacterium Xanthomonas citri pv. citri

“…These plant responses to wounds are known to be a deterrent against further invasion by plant pathogens (Dienelt and Lawson, 1989). The effect of wounding was particularly severe on mature citrus leaves in canker development and symptom expression (Verniere et al, 2003). The formation of a periderm, suberized and lignified cell walls, surface lamellae, and layered cell wall thickening was associated with an array of wound healing processes of Mexican lime leaves that were needle-inoculated with the citrus canker pathogen (Dienelt and Lawson, 1989).…”

Present status of the black rot disease of tea in Bangladesh

“…Young fruit and leaf tissues of citrus are more susceptible to Xanthomonas axonopodis pv. citri (citrus canker) than mature tissues (Verniere et al, 2003). The Survey areas intimate mixing of varieties is a proven method in certain cropping systems of introducing diversity to reduce plant disease (Wolfe, 1985, Akem et al, 2000and Zhu et al, 2000.…”

Produção de frutos e incidência de cancro cítrico em laranjeiras "Monte Parnaso" enxertadas sobre sete porta-enxertos

“…Portanto, essas lesões se tornariam visíveis só algum tempo mais tarde e, como no intervalo não foram feitas verificações, as lesões só foram computadas em junho. Observou-se também que, no período de abril/maio, houve temperaturas em torno de 25ºC e chuvas de até 190mm, suficientemente altas para possibilitarem a brotação das plantas e as infecções de CC (AMARAL, 2003;VERNIERE et al, 2003).…”