... c khoai t y b nhim nhiu virus cựng lỳc (X, S, M) (V Triu Mõn, 1986) [6] 1.2.2.2 Lan truyn ca virus khoai t y Cỏc virus khoai t y c truyn cú hiu qu bi rp Rp cú th nh c khoai t y hay di c t c y ... quan trng nht l ging khoai t y v chng virus 1.3.6.2 Cỏc chng v cỏc bin th ca PVY khoai t y PVY khoai t y c chia thnh chng (PVYO, PVYN v PVYC), nhiu bin th PVYO, PVYN v PVYC c phõn bit da trờn ... chng (PVYO, PVYN, PVYC) g y cỏc triu chng khỏc c y khoai t y: + PVYO: Khi l y nhim ln u (primer), phn ng ca c y vi chng virus ny ph thuc vo ging khoai t y Lỏ c y cú th cht hoi, to m hay ng vng,...