versão impressa ISSN 0006-8705
ROSSETTI, Vitória e SALIBE, Ary A.. Prevalência das doenças de vírus dos citros no estado de São Paulo. Bragantia [online]. 1962, vol.21, n.unico, pp. 107-121. ISSN 0006-8705. http://dx.doi.org/10.1590/S0006-87051962000100009.
A survey of the virus disease conditions of the citrus orchards, giving special attention to bud-transmitted virus diseases was carried out in the State of Soo Paulo, Brazil, in order to lay a basis for a Budwood Certification Program. The field survey was based on a sample corresponding to 10% of the total population of 14 million citrus trees in the four main citrus areos of the State. In each area a certain number of orchards were selected according to scion and stock varieties and oge. tn each orchard counts were made for visible symptoms of psorosis., exocortis and xyloporosis on 100 trees taken at random. From the percentage of disease affected trees of each variety, found in the orchards, the weighted mean percentage was calculated for the total number of trees of the local samples considered for each disease, in each citrus area. Whereas a variable percentage of trees of the Pera variety with both exocortis and psorosis was recorded pointing to different sources of budwood, the trees of Baianinha and Hamlin varieties were practically 100 per cent infected with exocortis, which is to be expected since they all have originated from the same budwood sources. Psorosis was not found on Hamlin trees, but proctically in all trees of the Baianinha variety. Symptoms of xyloporosis were observed on the Barão variety only. Observations on the occurrence of more or less severe strains of the tristeza virus were made, and symptoms of the disease were found on Pera orange, grape-fruit and West Indian lime.