Forecast Of Pest Disease On The Tender Tip Of Picea Crassifolia In Gansu Qilian Mountain Nature Reserve

Monitoring and investigation of pest disease on the tender tip of Picea crassifolia in Gansu Qilian Mountain were conducted from 1998 to 2005, through combination of fostering in rooms and timely monitoring and investigation in the forest. Based on the monitoring and forecast of pest disease conducted in Qilian mountain as well as the available data, research on the occurring, distribution and forecast of pest disease on the main tender tip of Picea crassifolia was conducted systematically. The following results were gained: (1) The relation between the phenology of plants in the forest and the occurring time of five key pest diseases (D. schuetzeella Fuchs, Lozotaenza coniferana (Issiki), Choristoneura diversana(Hubner), Acantholyda piceacola Xiao et zhou, C. danbaica Xiao) was observed and recorded; the ecological characteristics of pest disease, such as life habit, life span, food requirement, sexual ratio and reproductive capacity, were described. (2) Through investigation along the road, combined with investigation in the standard plot, the effect of climatic factors, landforms, tree species and artificial factors on occurring of pest disease were investigated; the climate under which pest disease occurred was observed; relationship between climate and pest disease was analyzed. The investigation reveals: the harm from pest disease on tender tip is more severe in the area with low elevation than that in high elevation, more severe in lower slope than that in middle and upper slope, more severe along the edge of forest than that inside the forest, more severe in the forest with low canopy density (lower than 0.4) than in that with high canopy density, more severe in south slope than that in north slope, more severe in the year with little rain than that with plentiful rain. (3). The community dynamics, distribution and harm of pest disease on the tender tip of Picea crassifolia in Qilian Mountain nature reserve was analyzed. The result shows: D. schuetzeella Fuchs, Lozotaenza coniferana (Issiki) and Choristoneura diversana(Htibner) are the 3 main pest diseases in the tender tip of Picea crassifolia, with large quantity of communities, wide distribution and serious damage. Normally, they mixed with other small moths. The small moths usually have one generation each year, the larva will eat out leaves and tips, which will cause reduction of leaves on the tip, death of the tip bud and poor growth of trees, thus no fruits can bear. Pest disease occurs in the forest with different elevation, while the harm of that occurred in the forest with low elevation is more serious. (4) The quantity and harm of pest disease on different tender tip was researched, and the regulations of quantity and harm of pest disease were basically mastered. (5). Through field investigation and observation, the death rate of C. danbaica Xiao in different periods were made clear, and the life span table of natural C. danbaica Xiao was made. (6). Based on the occurring period and death rate of pest disease, forecast model of short and medium-term occurring of D. schuetzeella Fuchs, Acantholyda piceacola Xiao et zho, Lozotaenza coniferana (Issiki) and C. danbaica Xiao was set up through applying effective baseline method. (7). Forecast and analysis of pest disease occurring tendency in the tender tip were undertaken. (8). The reasons causing pest disease were analyzed, and the comprehensive measures for killing it were put forward. (9). Mechanical measures for controlling pest disease on tender tip of Picea crassifolia were applied, which have effectively stopped it from spreading, well protected the forestry resources and eco-environment in Qilian mountain. Significant economic, ecological and social effects have been gained in this regard.