Pine needle spot

Pine needle spot is a highly contagious disease caused by the fungi Aspergillus subsp. The major hazards are spruce and Pinus sylvestris. Symptoms: The disease usually occurs at the tip of the leaf. At the beginning of the disease, the center of the lesion gradually changes to brown, and as the lesion expands, it gradually changes from red to reddish-brown, showing a short strip (see picture). Onset of heavy needles, lesions covered with the entire leaf, resulting in yellow needles, early leaves. The needle on the lower branch of the canopy begins to develop and gradually develops above the crown. Severely diseased trees are fire-like. The diseased tree grows weak and gradually withers. Pathogenesis: Pathogens use hyphae and immature conidia plates to overwinter in pine needles. Conidia are produced from early May to early June. Conidia are spread by rainwater and scattered from stomata or wounds. Inside. Conidial spores are closely related to temperature and humidity. When the humidity is high after rain, spores are scattered. Control methods: (1) Strengthening quarantine: Pinellia rosacea is a newly discovered disease in China in recent years. There is a serious trend in Heilongjiang Province. Doing a good job in quarantine work is the main way to prevent the spread of the disease. (2) Pruning of diseased needles: Concentrate deep or burn, reducing important sources of infection. (3) Strengthen cultivation management, timely watering, increase fertilization, and increase the resistance of trees to disease. (4) Chemical control: After the trees grow new leaves, before the spores are released, and when the spores are prosperous, spray 75% chlorothalonil 600-1000 times, all have certain control effects. (Source: China Flower News, Qi Xiangjun, Zhao Guiqin)