Abstract:

Arceuthobium sichuanense is the most important vascular parasite on Picea crassifolia, Picea purpurea, Picea likiangensis var. balfouriana and Picea spinulosa in Sichuan, Qinghai and Tibet, and has severely damaged forest stands by dispersing explosive fruits in August and September in Sanjiangyuan area of Qinghai Province. A. sichuanense affects host growth through the interaction of the host with the mistletoe endophytic system, and expropriates water, minerals, and carbohydrates from the host, causes deformation of the infected stem, increases susceptibility to other disease agents or insect pests, and reduced the host longevity. To select the best measure for control ofA.sichuanense flowering buds in its early days and the flowering dynamics were investigated in its initial flowering phase (in the middle of May). The results showed that the flowering span of A.sichuanense populations was more than 40 days, while individual parasite was flowering for around 15 days. Greenish fruits emerged in 6-8 days after the flowering span, and the fruit pedicel elongated to 1-1.5 mm in its explosive span. Meanwhile, four kinds of plant hormones including 40% ethephon aqueous solution, 50％ daminozide water solution powder, 20% 1-naphthylacetic acid dust and 90.8% abscisic acid were applied to the flowering buds of A.sichuanense. The results showed that all diluted 40％ ethephon（diluted 100,200 and 400 fold）killed the flowering buds successfully and the mortality of flowering buds reached nearly 100%. The dilution of 1∶400 was the best choice because it was harmless to spruce needles and branches. Although the other three kinds of plant hormones also had relative effects, they were not suitable for epidemic prevention in large areas in regard of the cost and ecological concerns.

Key words: Arceuthobium sichuanense, flowering phase, flowering characteristics, ethephon