A Detailed Guide to the Latest Control Methods for Black Rot of Mustard

Mustard can be pickled for eating or its seeds made into mustard for consumption, and the whole plant can be used as medicine, giving it a certain economic value. Mustard generally suffers from few diseases when grown, but it should not be taken lightly, as black rot of mustard occurs frequently, and the pathogen can survive in a variety of environments. So it is important to pay attention to it, and next we will briefly introduce the control of black rot.

I. Disease Symptoms

It mainly harms the leaves, but the whole plant can be affected, usually invading through wounds or tender parts. After being affected, withered yellow lesions generally appear first at the leaf edges, gradually spreading inward, and the pathogen spreads along the leaf veins toward the stem, forming brown lesions. The leaves eventually become dry-rot-like, but the stem may rot and fall off, and in the end everything becomes dried out.

II. Causes of Infection

It breaks out abundantly under high temperature and high humidity, dies below a low temperature of 5 degrees, and tolerates high temperatures. The initial infection may come from seed carrying the pathogen, or the selected planting field may have had the pathogen before. The pathogen can survive in the soil for several years and continue to cause harm. It can generally spread with irrigation water, wind, and farming operations. If water remains on the leaf surface after heavy rain, infection is likely. It can overwinter in diseased residues and soil.

III. Key Control Points

1. Seed and Site Selection

Choose disease-resistant varieties, choose varieties with lower water requirements that are more drought-tolerant, and choose varieties adapted to high-temperature and rainy weather. Generally, the land selected should be land where no black rot-susceptible host plants have been grown before or where black rot has not occurred, and it is best if no susceptible plants of the same kind are grown nearby.

2. Cultivation Management

Sowing can be done appropriately early to avoid the high-temperature and rainy weather of summer, and when transplanting, seedlings should be hardened off to strengthen disease resistance and adaptability. Drain promptly after rain, and in drought, water promptly after the soil temperature drops. Irrigation only needs to keep the soil alternately dry and moist, not overly wet.

3. Seed Treatment with Chemicals

Before sowing, stir in 50-degree hot water for 10 minutes to sterilize, then after draining, soak the seeds in a 300-fold solution of 45% amobam aqueous solution for half an hour to sterilize and disinfect, then dry them before sowing to avoid carrying the pathogen. Use chemicals promptly at the early stage of disease onset; generally, spray with a 4000-fold solution of 72% agricultural streptomycin sulfate soluble powder, spraying twice in a row with a three-day interval. If the spread is not controlled, promptly pull out severely diseased plants or even replace the soil, then switch to a 300-500-fold solution of 15% mixed amino acid copper·zinc·manganese·magnesium aqueous solution or 1500-fold 50% chlorobromoisocyanuric acid soluble powder for control.

Preventive work should be done well before black rot occurs, which can minimize the possibility of disease occurrence to the greatest extent, and then it is necessary to control it promptly at the early stage of onset to prevent spread. Doing these well can prevent the disease from breaking out over a large area.