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MANDARIN ORANGE Tristiza Virus

Name of Crop MANDARIN ORANGE
Scientific Name Citrus reticulate
Local Name Santra
Family Rutaceae
Common Name of Disease TRISTIZA VIRUS DISEASE
Local Name of Disease TRISTIZA VIRUS
Causal Organism Citrus tristiza virus
Distribution of Disease in Sikkim Through out the citrus growing areas of Sikkim
Disease Incidence Moderate
Dissemination of the Disease It is neither a seed borne nor soil borne disease. Disease is transmitted by aphids
Symptoms                                   The term ‘Tristiza’ means sad appearance. The first symptoms may appear only on one branch but a large portion of tree is involved later on. Older leaves become bronze                                      at first but slowly  may take various shades of yellow. The yellowing seems to be more intense in the mid rib or lateral veins. Older leaves fall off. Diseased trees have a                                           tendency to blossom heavily in the  early  stage of attack and usually set heavy fruits. The branches and stems are also severely pitted
Favourable enviromental condition
for disease		 Poor maintenance of orchard, lack of monitoring of crop infestation by aphids
Mode of Transmission The tristiza virus is mainly transmitted by the vector aphid
Plant Protection Measures                Grow resistant varieties. Use certified bud sticks free from tristiza virus. Use resistant root stock. Control vector by using organic pesticide (Nimbicidin) @ 3ml/lit water                                                                  fortnightly. Removal of  alternate hosts of insect vector. Insect proof netting to be done to nursery bed of the orange seedlings
Brief History of Disease                     Sikkim, Assam, Meghalaya, Nagpur, Darjeeling Nepal, Bhutan