Broccoli Black Rot Control Methods and High-Yield Cultivation Techniques for Edible Fungi

Symptoms of Broccoli Black Rot

Broccoli black rot damages leaves and the head. Infected cotyledons become water-soaked and then rapidly die off or spread to the true leaves. There are two types of infection on true leaves. When the pathogen enters through water pores, it causes disease at the leaf margin, forming a "V"-shaped necrotic spot that starts from the leaf margin and extends inward; the pathogen spreads downward along the veins, forming a larger necrotic area or irregular yellow-brown large spots, with the leaf tissue at the edge of the lesion appearing pale yellow. When the pathogen enters through wounds, it can form irregular light brown lesions on any part of the leaf, often with a yellow halo at the margins; the lesions expand laterally or inward, causing the surrounding mesophyll to turn yellow or die. After the pathogen enters the vascular bundles of the stem, it gradually spreads to the head or to the veins and petioles, causing the plant to wilt, and the wilt does not recover. When the head is cut open, all vascular bundles can be seen to have turned black or rotted, but without a foul odor. Under dry conditions, the head develops a black heart. In severe cases, multiple sites along the leaf margins of broccoli are infected, causing the entire leaf to die or the outer leaves to partially or largely rot.

Control Methods for Broccoli Black Rot

(1) Plant disease-resistant varieties such as Zhongqing No. 1 and No. 2.

(2) Carry out a 2-3 year rotation with non-cruciferous vegetables.

(3) Collect seeds from disease-free fields or disease-free plants.

(4) Seed disinfection: add 0.6 mL of acetic acid and 2.9 mL of zinc sulfate to 100 mL of water, dissolve, then control the temperature at 39°C, soak the seeds for 20 minutes, rinse for 3 minutes, air-dry, and sow. Alternatively, soak the seeds in a 300-fold dilution of 45% amobam aqueous solution for 15-20 minutes, rinse, air-dry, and sow; or treat the seeds with 50% copper succinate wettable powder at 0.4% of seed weight, which can prevent the occurrence of black rot at the seedling stage. In addition, 15 mL of a 100-fold dilution of the agricultural antibiotic 751 fungicide can be used to soak and mix 200 g of seeds, and after adsorption, dry them in the shade; or for each kg of seeds, use 10-20 g of bleaching powder (active ingredient) plus a small amount of water, mix the seeds evenly, then place them in a container and seal for 16 hours. All of these methods can effectively control the black rot pathogen carried on the seeds of cruciferous vegetables.

(5) Strengthen cultivation management. Sow at the appropriate time; sowing too early should be avoided. Water rationally and practice seedling restraint at the proper time; take care to reduce wounds; clean the field promptly after harvest.

(6) At the early stage of disease, spray 72% agricultural streptomycin sulfate soluble powder or novobiocin at 200×10-6, or chloramphenicol at 100×10-6, or 27% copper hydroxide suspension concentrate at a 700-fold dilution. Stop applying the pesticide 5 days before harvest.