Application of Micronutrients Enhances the Quality of Kinnow Mandarin Infected by Citrus Greening Disease (Huanglongbing)

Citrus greening disease (CGD) is one of the economically significant diseases of Kinnow mandarin. Various management practices have been adopted to mitigate this disease. However, this disease can only be effectively minimized by the application of micronutrients which play an essential role in increasing the vigour of citrus against the disease. In the present study, typical symptoms of citrus greening, such as mottled leaves, were observed on the infected trees. The infected fruits were undeveloped and partially or entirely failed in attaining natural orange fruit colour. Moreover, the iodo-starch tests revealed that the color of HLB-positive leaves was dark grey to black across the sliced surface. Afterward, the Zinc sulfate and Manganese sulfate at the concentrations of 0.25 g/L, 0.5 g/L, and 0.75 g/L were applied on selected diseased plants in combination. Afterward, different vegetative, physiological, and biochemical parameters of citrus greening infected fruit include fruit diameter, fruit weight, flavedo thickness, total soluble solids, ascorbic acids, juice percentages, TSS/TA ratio, total soluble solids, and titratable acidity were statistically analyzed. The application of Zinc sulphate (0.75 g/L) combined with Manganese sulphate (0.75 g/L) had significantly increased the fruit diameter, fruit weight, flavedo thickness, total soluble solids, ascorbic acids, juice percentage, and TSS/TA ratio in the citrus greening diseased affected fruits. The other parameters such as titratable acidity, total sugars, reducing and non-reducing sugars in the citrus greening diseased affected fruits were not influenced significantly.