How to control the main pests and diseases of Gentiana macrophylla such as leaf rust, root rot and aphids?

Gentiana macrophylla, also known as large-leaf gentian, large-leaf Qinjiao and West Qinjiao, is a perennial herbaceous plant and one of the main drugs for treating rheumatism, joint pain, tuberculosis, tidal fever, jaundice and other conditions.So what are the main pests and diseases of the herbaceous plant Gentiana macrophylla, such as leaf rust, root rot and aphids, and their control measures?Let's learn about them together below.

I. Main diseases of Gentiana macrophylla and control measures

1. Leaf rust: High temperature and high humidity in the field easily induce this disease. It mainly infects the leaves. In the early stage, yellow dot-like protrusions appear on the front of the leaves, and in the later stage the lesions spread, expand and merge. On the back are yellow protruding spots, namely spore pustules. When the disease is severe, the leaves wither, turn yellow and die.

Control measures: After autumn, thoroughly remove the diseased plant residues from the field and burn them in a centralized manner. For sporadic occurrence, use 25% triadimefon 200-fold solution, myclobutanil 800-fold solution, 50% kresoxim-methyl 800-fold solution and other agents, and spray them in rotation.

2. Viral disease: This disease is mainly transmitted by thrips. In the early stage of the disease, faded green yellow-green spots appear on the leaves, and as the disease gradually becomes more severe. In the later stage, the lesions expand and increase, covering the leaves with yellow-green round spots, and finally the entire leaf turns yellow until the plant withers and dies.

Control measures: Strengthen field management, and promptly clean up the remaining plants in the field after harvest to eliminate the primary infection source of the virus. Before early spring, thoroughly remove dead branches, fallen leaves and weeds in the field and burn them in a centralized manner to eliminate overwintering eggs. In the early stage of the disease, use 20% virus A, 1.5% zhibingling, 20% moroxydine hydrochloride wettable powder, 7.5% junduqing and other agents for spray control, and at the same time spray potassium dihydrogen phosphate foliar fertilizer.

3. Root rot: Injuries to the plant roots, continuous cropping and water accumulation in the field easily cause this disease. It mainly harms the roots. After infection, the roots gradually turn black, and later rot. The lower leaves of the plant turn yellow, and in severe cases the plant withers and dies.

Control measures: Implement crop rotation, drain water promptly after rain, and apply decomposed farmyard manure. In the early stage of the disease, use 70% thiophanate-methyl 600-fold solution, 75% chlorothalonil 600-fold solution, 50% chlorobromoisocyanuric acid 800-fold solution in rotation for root drenching.

II. Main insect pests of Gentiana macrophylla and control measures

The insect pests are mainly aphids and thrips.

The damage is most severe during the flowering period. When infestation occurs, biological control can be carried out using natural enemies such as ladybugs and hoverflies, or yellow and blue sticky boards can be used for trapping and killing, or 10% imidacloprid and 5% acetamiprid can be sprayed for control. For underground pests, emamectin benzoate poison bait can be used for trapping and killing.