Carrot black rot, which seriously affects the yield of carrots, and also reduces the quality, it is necessary to carry out pesticide control in time. China Pesticide Network Xiaobian organizes relevant disease information for your reference:
Pathogen Alternariaradicina
The main symptoms can occur from seedling stage to harvesting stage or storage period, mainly affecting fleshy roots, leaves, petioles and stems. The leaves are infected, forming dark brown spots, and the leaves are dead. The lesions on the petiole are long. Most of the stems are fusiform to long strips with no obvious edges. When the humidity is high, the surface is densely covered with black mold. The fleshy roots are infected, and irregular spots or rounded black spots are formed on the roots. In severe cases, the lesions expand and reach the inside, causing the fleshy roots to become black and rot.
According to the pesticide network , the pathogenic conditions mainly depend on the conidia or mycelium to overwinter on the sick body. In the spring, the conidia spread by airflow. Warm and rainy weather is beneficial to the disease.
Prevention and control method 1 Agricultural measures: Seed collection from disease-free plants, so that single collections can be collected. Implemented for more than 2 years of rotation. Increase the application of base fertilizer to promote its growth and strengthen disease resistance.
2 seed disinfection: before planting with a seed weight of 0.3% of 50% thiram double wettable powder, or 40% seed dressing double powder, or 70% mancozeb WP, or 75% chlorothalonil WP, or 50% chlorhexidine WP powder dressing.
3 pesticide control: start spraying 75% chlorothalonil WP 600 times liquid, or 58% metalaxyl · manganese zinc wettable powder 400 ~ 500 times liquid, or 40% gram dandan wet powder 300 ~ 400 Double solution, or 56% chlorpyrifos WP 700 times solution, or 69% manganese zinc enoyl (an Mn Zn) wettable powder 600 times solution, or 60% fluorine Mn·Mn Zn (killing) Wet powder 750 ~ 1000 times liquid, or 50% nail cream copper wettable powder 600 times liquid, or 50% chlorhexidine wettable powder 1500 times liquid, every 10 days or so, continuous control 3 to 4 times.
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