Journal of Plant Pathology (2007) 89, p. S38 (Davino et al.)

S. Davino, G. Sorrentino, M. Guardo, M. Davino and A. Caruso (2007)
Observations on the rapid spread of severe isolates of Citrus tristeza virus by Aphis gossypii
Journal of Plant Pathology 89 (3, Suppl.), S38-S38
Poster Presentation at S.I.Pa.V XIV National Meeting - Perugia, Italy 19-21 Sept. 2007
Abstract: The discovery of a large focus of Citrus tristeza virus (CTV) in Sicily has allowed to process a prediction model of CTV spreading at Baé in the province of Catania. Investigations were carried out in three different groves of sweet orange cv. Tarocco O.L. grafted on sour orange. All trees in each grove were sampled yearly in May and September from 2002 to 2007. Four young apical shoots were collected from each tree and analyzed by DASELISA and DTBIA. Molecular tests, SSCP and sequencing of P20 and P23 genes, showed that the viral isolates present in these groves belonng to the seedling yellow strain (CTV-DS2). Monitoring of aphid population in all plots confirmed the results reported in preceding works, indicating that Aphis gossypii Glover represented 85-90% of the aphid population. Our results about the percentage infected trees are very similar to nonlinear predictive model estimation of CTV spread, reported from other citrus areas where the vector is A. gossypii until the 7th-8th year from the beginning of infection. However, after eleven years the percentage of infected trees in all plots in our nonlinear prediction model was ca 98%, a figure which, elsewhere, is reached in the 14 th -15 th year. This more rapid spreading of CTV in Sicily, just after the 8 th year of infection, may depend on the severe CTV isolate present (seedling yellow) combined with the high susceptibility of Tarocco O.L. grafted on sour orange.
Database assignments for author(s): Salvatore Walter Davino, Maria Guardo, Guido Sorrentino

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aphis gossypii	Citrus (genus)	Italy
	Citrus tristeza virus	Citrus (genus)	Italy