What Causes Tip Burn in Welsh Onions? Cause Analysis and Control Measures
Welsh onions are grown fairly widely in China, mainly in the northern regions, but tip burn can occur during cultivation. Tip burn has become a major obstacle in Welsh onion production, often leading to reduced yield and quality and directly affecting growers' income. So what causes tip burn in Welsh onions? How can it be controlled? Let's take a look.
1. Tip burn caused by disease
Disease is one of the main causes of tip burn in Welsh onions. When Welsh onions are affected by late blight, pale bluish-white spots appear on the affected areas and gradually spread into grayish-white patches, causing the leaves to wither from the bottom upward and resulting in tip burn. When gray mold occurs, white spots also appear on the leaves, all developing downward from the leaf tip, and gray mold may also appear on the lesions when humidity is high. Root rot can also cause the leaf tips of Welsh onions to turn yellow and gradually wither and die. All three of these diseases can cause tip burn.
Control measures: For late blight, spray leaves or drench roots with (shuangyi); for gray mold, spray with procymidone or iprodione; for root rot, spray and drench roots with hymexazol or metalaxyl.
2. Tip burn caused by insect pests
Many pests can also cause tip burn in Welsh onions, such as thrips, which mainly damage the leaves of Welsh onions, causing irregular grayish-white spots on the leaves and, in severe cases, withered leaves. Somewhat similar to thrips, leafminers and beet armyworms behave the same way: their larvae bore into the leaves and feed on the mesophyll tissue, leaving only the dried epidermis of the leaves.
Control measures: For thrips, spray with bifenthrin; for leafminers, spray with cyromazine once every 5 days for 2-3 consecutive applications; for beet armyworms, spray with emamectin benzoate and chlorfenapyr.
3. Physiological tip burn
In addition to pests and diseases causing tip burn in Welsh onions, improper practices in daily management can also cause tip burn. When Welsh onions lack calcium or boron, their growth and development are hindered, leading to withered leaves and tip burn. A lack of water in the plants can also cause tip burn; using pesticides at too high a concentration can also cause the leaves to turn white or develop tip burn.
Control measures: Apply sufficient base fertilizer, mainly organic fertilizer or farmyard manure, and when plants are found to lack trace elements, supplement them by foliar spraying. Pay attention to water management: water promptly during drought, and also pay attention to drainage during the rainy season, keeping soil moisture content at 60%-80%. When using pesticides, strictly follow the instructions and do not make the concentration too strong; after pesticide damage occurs, promptly spray a remedy.
The above is an introduction to the causes of tip burn in Welsh onions and control measures. We hope it helps you. To learn more related knowledge, please follow us.