Further Studies of Citrus Seedling Yellows Virus in the Deccan Trap Country

Seedling yellows virus was isolated from a declining ‘Mosambi’ sweet orange tree by using Toxoptera citricida (Kirk.) and maintained in culture in Mexican lime seedlings designated ASY source plants. When seedlings of Kagzi lime, grapefruit cv. ‘Marsh Seedless’, sour orange cv. ‘Seville’, ‘Eureka’ lemon and ‘Mosambi’ sweet orange were inoculated by leaf-patch grafting from the ASY source, Kagzi lime initially showed a shock reaction followed by vein flecking and wood pitting typical of the lime reaction. Grapefruit, sour orange and ‘Eureka’ lemon gave a typical seedling yellows reaction. ‘Mosambi’ sweet orange showed no visible symptoms but continued to carry the SY virus symptomlessly for at least 470 days. Back inoculation by leaf-patch grafting from recovered plants of ‘Eureka’ lemon and Kagzi lime indicated that the reaction in these test seedlings was caused only by the seedling yellows virus, a severe strain of the tristeza virus.