The false black spot disease of rapeseed, also known as the small black spot, primarily affects the leaves of the plant. In severe cases, the lesions merge, leading to leaf drying and, in some instances, the disease may co-occur with black spot. Prompt application of pesticides is essential for effective control. According to **The China Pesticide Network**, Xiaobian has compiled detailed prevention strategies to help manage this issue.
The pathogen responsible for the disease is *Alternaria alternata* (Fries) Keissl., formerly known as *A. tenuis* Nees. It is a fungal species that forms conidiophores in clusters—dark brown, short, thick, or irregularly shaped, with 2–9 septa. The conidia are inverted bar-shaped or cylindrical, pale yellow, measuring between 9.5–40 × 5–11.25 micrometers. They typically have 1–6 septa, most commonly 3–4, and feature a short beak, which is about half the length of the spore. Some conidia have one or two septa and are colorless.
The vegetative hyphae of this fungus can be mononuclear, binuclear, or trinuclear, but the tip cells of new hyphae are often multinucleated. Conidia cells are mostly mononuclear, but the widest spores usually contain 2–3 nuclei. The mycelium forms collaterals, and when forming spore stalks or spore-bearing structures, daughter cells grow from the mother cell, with one nucleus migrating into the new cell. This process continues, allowing for the development of collaterals, conidiophores, and conidia.
Previously, the bacterium was considered saprophytic, but under favorable conditions, it can become weakly parasitic, causing damage to the host. This transition turns saprophytes into pathogens.
The disease spreads through infected seedlings, seeds, diseased plant parts, or soil. The pathogen overwinters or oversummers in the soil, serving as an initial infection source. Conidia spread via wind, leading to secondary infections and continuous disease outbreaks. According to the **pesticide network**, the pathogen thrives between 10–35°C, with an optimal temperature of 17°C and a pH of 6.6. It can survive in water for up to a month, in soil for three months, and on the soil surface for a year. The disease typically occurs during the middle to late growth stages of rapeseed or during off-season cultivation, making it more prevalent and increasingly serious in recent years.
Control measures include:
1. Crop rotation and thorough field cleanup after harvest to reduce bacterial sources.
2. Using compost made by Japanese enzyme bacteria or manure compost to promote beneficial microbes and improve plant resistance.
3. Selecting resistant varieties such as Qinbai No. 2, Yuyou No. 3, Zhengbai No. 4, Xiaoyeqing, and Rongbai No. 4.
4. Seed disinfection using 0.4% chlorhexidine WP at 50% of the seed weight or 75% chlorothalonil WP.
5. Spraying solutions like 64% antivirus WP diluted 500 times, 40% chlorothalonil suspension 500 times, 70% mancozeb WP 500 times, 58% metalaxyl MnZn wettable powder 500 times, 80% spray WP 600 times, 50% phlegm hygroscopic powder, or a 1000-time dilution of its compound agent.
When black spot disease and downy mildew occur together, it is recommended to use 70% ethyl phosphine•manganese zinc wettable powder 500 times, 60% succinylphosphine aluminum (DTM) wettable powder 500 times, 72% frost urea manganese zinc (Ke anti-linguistic) wettable powder 800 times, or 69% Anke manganese zinc wettable powder 1000 times. Apply approximately 660 liters per 667 m², repeating every 7–10 days for 3–4 applications. Stop applying **pesticides** 7 days before harvesting.
As one of the world's largest producers of Pvc floor mats, China can offer competitive prices. Under the scale of our productivity, the labor cost is relatively low, which makes the price of China's Non Slip Floor Mats in the international market has the advantage of being low, which fully meets the demand for economic products in the European and American markets, and our supply chain production capacity can meet large orders and complete a stable and continuous supply, which ensures that the market needs are met.
PVC Floor Mats,Pvc Mats Online,Custom Plastic Floor,Industrial Non Slip Rubber Matting,Kitchen Mats
Jiangyin Yining E-Commerce Co., Ltd , https://www.pvcmatyining.com