Virus Infection of Forest Trees by Mechanical Transmission

Abstract Back transmission trials on young forest plants with isolates of purified viruses from the same tree species were performed using different inoculation techniques. Spruce seedlings and willow plants were successfully infected with tobacco necrosis virus (TNV) by the conventional method of mechanical inoculation of virus suspension mixed with celite as abrasive. Cherry leaf roll virus (CLRV) was transmitted to birches only after adding poly-L-orithine (PLO) to the inoculum. The same method was successful with brome mosaic virus (BMV) on beech seedlings. PLO also improved the rate of infection on TNV in willows. In only one case, was CLRV transmitted conventionally to a white ash seedling. The infection of white ash was increased when frozen powders, of infected ash leaves were directly rubbed onto leaves. BMV could not be transmitted to beech seedlings by carborundum pressure-inoculation. Stem slashing-inoculation of BMV and CLRV was successful with CLRV in one beech out of 60 seedlings.