Disease control techniques of Radix scrophulariae

1. White silk disease: it damages the roots, which occurs in late April, and is serious from July to August until September. The diseased root and rhizosphere soil were covered with white sericeous hyphae and planted light yellow to tea-brown sclerotia, and the diseased plants wilted and died rapidly.

Prevention and control methods:

(1) rotation with Gramineae crops for more than two years

(2) rational fertilization, good water management, removal of weeds in the field, and timely removal of diseased plants at the initial stage of the disease.

(3) Drug control: choose 20% triadimefon EC 500x solution, 15% carbendazim water agent + 70% mancozeb 800x solution, 70% methyl thiophanate 800x solution, 5% Jinggangmycin water agent 500x liquid, 50% tianan water agent 500600x solution, 20% methyl risperidone 1000 times solution, 50% promethopril 1500 times and other medicine solution to spray rain alternately.

2. Leaf blight (Tiejiao leaf): it occurred in the middle of April, was more serious from May to June, and gradually alleviated due to the increase of temperature after July. In the early stage of the disease, purple-brown sunken spots appeared on the leaf surface, and the center was white or gray-white spots. With the continuous development of the disease, a large gray-white spot was formed, showing a polygonal irregular shape with a diameter of 1-5 mm. The plaque is sometimes divided into reticulate veins with purplish brown edges. There are many small black spots scattered on the disease spot, that is, the conidium of the pathogen. The size of the lesion is generally 0.5-2cm in diameter. In severe cases, the disease spots converge to form irregular spots, and finally the whole leaf dies.

Prevention and control methods: (1) agricultural measures are the same as white silk disease; (2) Chemical control: alternately spraying 75% chlorothalonil 1500 times solution, 70% methyl thiophanate 800 times solution, 70% mancozeb 800 times solution and so on.