How to prevent and control Scrophularia ningpoensis diseases? Detailed technical points

1. Southern blight: It damages the roots, occurs in late April, causes severe damage from July to August and continues until September. The diseased roots and the rhizosphere soil are covered with white silky hyphae, and light yellow to tea-brown seed-like sclerotia are attached. The diseased plants rapidly wilt and die.

Control methods:

(1) Carry out crop rotation with gramineous crops for more than two years;

(2) Apply fertilizer reasonably, manage water well, remove weeds in the field, and promptly remove diseased plants at the early stage of disease occurrence;

(3) Chemical control: options include 20% triadimefon emulsifiable concentrate at 500 times dilution; 15% hymexazol aqueous solution + 70% mancozeb at 800 times dilution; 70% thiophanate-methyl at 800 times dilution, 5% jinggangmycin aqueous solution at 500 times dilution; 50% tianan aqueous solution at 500-600 times dilution; 20% tolclofos-methyl at 1000 times dilution; 50% procymidone at 1500 times dilution and other solutions applied alternately as sprays for control.

2. Leaf blight (iron scorch leaf): It occurs in mid-April, is more severe from May to June, and after July the condition gradually lessens as temperatures rise. At the early stage of the disease, sunken purplish-brown lesions appear on the leaf surface, with white or grayish-white small spots in the center. As the disease progresses, large grayish-white lesions form, polygonal and irregular in shape, 1-5 mm in diameter. The lesions are sometimes divided by leaf veins into a net-like pattern, with purplish-brown edges. Many small black dots are scattered on the lesions, namely the pathogen's pycnidia. The lesions are generally 0.5-2 cm in diameter. In severe cases, the lesions merge with each other into irregular large spots, and finally the entire leaf withers and dies.

Control methods: (1) Agricultural measures are the same as for southern blight; (2) Chemical control: options include 75% chlorothalonil at 1500 times dilution; 70% thiophanate-methyl at 800 times dilution; 70% mancozeb at 800 times dilution and other solutions applied alternately as sprays for control.