Critical time for the occurrence and development of tungro infection in the field [Philippines].
1987
Tiongco E.R. | Cabunagan R.C. | Flores Z.M. | Hibino H.
Tungro infection, at very low rates, occurred in plants from uncovered seedbeds. However, no difference in infection to any of the tungro viruses occurred between the plants from covered and uncovered seedbeds after transplanting in the field. Although no symptoms were discernible, RTSV [Rice Tungro Spherical Virus] infection was detected in the plants by latex test at 14 DAT [days after transplanting]. Tungro symptoms were manifested by the infected plants between 22 and 35 DAT coinciding with the detection of infection with both RTBV [Rice Tungro Bacilliform Virus] and RTSV. Tungro infection on IR62 and IR64 also occurred in the same period of time. At 37 DAT, no difference in infection in the three distance classes of surrounding (direct neighbor, diagonal, distant) hills was obtained in TN1, IR36, and IR54 plants. With time, more direct neighbor hills of TN1 plants were infected while the infection rates in the three distance classes in IR36 and IR54 plants did not differ. Under controlled conditions in field cages, viruliferous leafhoppers spread tungro to rice plants nearer the virus source. Hence, the spread of tungro infection is more likely to occur in plants in proximity to the infected plants of a susceptible variety. The possible role of RTSV and the seedbeds in tungro epidemiology is discussed.
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