From the pictures you provided and the search results on the webpage, it seems that your pine is suffering from "rust disease". The non-dying branches in the picture have two characteristics: first, yellow spots on the leaves; second, white membranous covering. The dead branch in the picture has two characteristics: first, there are branches and leaves falling off; second, there are dark brown leaves.

In Baidu library there is an article "common pests and diseases of pine" wrote: "Rust

1. Symptoms

A variety of pine trees on the occurrence of needle rust, its symptoms are basically similar to the susceptible needles initially produce greenish yellow segments of the spot, on which the birth of dense yellow dots, and then become yellowish-brown to blackish-brown, that is, the sex sporangia. Subsequently, orange-yellow capsule-like protrusions appeared on the spot, for rust sporangium, rust sporangium is often connected, irregular cracking after maturity, scattered yellow powdery spores. Diseased leaves often remain on the white membrane-like envelope. Finally, the diseased leaves withered and fell off or the upper part of the spot died.

2. Pathogen and pathogenesis

Pine needle rust is caused by some fungal infections in the genus Coleosp ium spp of the subphylum Aspergillus. Various pine needle rust disease occurs in a similar pattern. It is required to complete its life history on two hosts. Phellinus and Phellinus albus sheath rust fungus, to sex sporangia in the pine needles over winter, the next year, from early April to late May in the pine needles to produce rust sporangia, rust spores through the air flow, respectively, Phellinus, Phellinus albus, July to September in the abaxial leaf formation of summer spore stacks, and then produce winter spore stacks. From August to September, the winter spores germinate under suitable conditions to produce tanspores in the infested pines, and produce sex sporangia on pine needles to overwinter. The incidence of mountain shady slopes is heavier than the sunny slopes; the incidence of the mountain in the middle and the lower part of the mountain is heavier than the upper part of the mountain.

3. Control measures

(1) Avoid Phellodendron Bark and Pinus sylvestris when creating mixed forests.

(2) Conditional areas can spray sulfur powder or 0.3-0.5oBe stone sulfur compound, or use 80% diclofenac ammonium 500 times liquid, or use 50% retrogradation 500 times liquid, etc. to control."