Variation in Incidence of Citrus Canker in Relation to Epidemiological Factors in District Toba Tek Singh, Pakistan

Citrus canker is the major threat to citrus production. Survey of different localities was conducted in the areas of Toba Tek Singh, Gojra, Kamalia and Pir Mahal for citrus canker disease incidence recording on five citrus varieties (Grapefruit, Sweet lemon, Lemon, Musambi and Kinnow). Maximum disease incidence (65%) was recorded in Kamalia during August and September and minimum disease incidence (18%) was recorded at Pir Mahal during May, 2019. Out of fifteen localities surveyed, maximum disease incidence (65%) was recorded in Chak 712GB from august to October and minimum disease incidence was recorded at Chak 330GB during May. Grapefruit being the most affected (65% in October) and Kinnow the least (7.5% in May). Environmental factors like maximum temperature, minimum temperature, rainfall, relative humidity and wind speed were correlated with citrus canker incidence on Grapefruit, Lemon, Sweet lemon, Musambi and Kinnow. Environmental factors...were positively correlated with disease incidence An increase in any of these parameters corresponded with an increase in citrus canker incidence. With every one-unit increase in maximum temperature, minimum temperature, rainfall, relative humidity and wind speed, disease incidence also increased. Characterization of environmental factors conducive for citrus canker disease development was determined on Grapefruit, Sweet lemon and Kinnow. Maximum disease development was recorded at 32-38oC maximum temperature, 18-29oC minimum temperature, 2-7.5mm rainfall, 2.5-6.5 km/h wind speed and 40-80% relative humidity. Special care of citrus orchards during August and September against citrus canker disease is suggested for citrus growers of Toba Tek Singh District.