Beautiful scenery tip rust of spruce

Beautiful scenery tip rust is a newly discovered disease on Qinghai spruce, which is mainly distributed in the spruce forest at an altitude of 2600-2800m in the eastern section of the northern slope of the Qilian Mountains in western Gansu. It is second only to Qinghai spruce leaf rust, and the onset period is about one month earlier than Qinghai spruce leaf rust.

The diseased buds of symptomatic spruce germinated 10-15 days earlier than those of healthy buds. At the beginning of June, the diseased buds expanded into a conical shape, showing peach red, and the surface was densely punctuated, which was called the diseased spore apparatus. The new leaves on the tender shoots are deformed, the leaf shape is slightly curved into a banana shape, and the surface is covered with yellowish-brown sporangium, and many orange strips and slightly raised spores appear one after another, and the color of the diseased tip changes to orange, which is bright in color and looks like beautiful flowers, so it is named spruce beautiful shoot rust. In the middle of June, the sporidium matured one after another, the capsule ruptured, and a large number of yellow powdery spores were released. In late June, the diseased tip gradually turned dark brown and withered, but it did not fall off on the branch all the year round, and the last year's damage could still be seen until the following year.

Pathogen PeridermiumgansuenseWusp.rov. It is called Rust in Gansu Province, which belongs to basidiomycete subphylum fungi. The sexual spore organ is nearly bottle-shaped, almost all protruding from the host tissue, with a diameter of 64-205 μ m; the gonospore is a long strip along the stomatal line of the needle, with a length of 4-12mm, some of which are almost as long as the diseased leaves, with a diameter of 210-705 μ m, and the maximum diameter can reach more than 1mm; the coated cells are irregularly long, with a size of 19-45 μ m × 17-32 μ m, with inner wall thickness of 3-5 μ m, outer wall of 5-7 μ m, and dense verrucous spots on both inner and outer walls. The spores are long ovate, ovate or suborbicular, 15-23 μ m × 21-37 μ m, 1-3 μ m thick, fine and dense verruca on the surface, yellowish brown.

The pathogen overwintered in the diseased bud and began to occur at the beginning of June of the following year, forming diseased shoots and becoming the source of primary infection. The disease is highly regional and selective to hosts, and often occurs in high, cold, shady and humid ecological conditions.