What causes dry leaf tips in Welsh onions? Cause analysis and control measures
Welsh onions are grown fairly widely in China, mainly in the northern regions, but during cultivation the phenomenon of dry leaf tips can appear. Dry tips have become a major obstacle in Welsh onion production, often leading to reduced yield and quality and directly affecting growers' income. So what causes dry leaf tips in Welsh onions? How can they be controlled? Let's take a look.
1. Dry tips caused by disease
Disease is one of the main causes of dry leaf tips in Welsh onions. When Welsh onions suffer from late blight, pale bluish-white spots appear at the affected sites and gradually spread into grayish-white patches, causing the leaves to wither from bottom to top and forming the dry-tip phenomenon. When gray mold occurs, white spots also appear on the leaves, all developing downward from the leaf tips, and in high humidity gray mold also appears on the lesions. 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 the dry-tip phenomenon.
Control measures: For late blight, spray leaves or drench roots with cymoxanil; for gray mold, spray with procymidone or iprodione; for root rot, spray and drench roots with hymexazol or metalaxyl.
2. Dry tips caused by insect pests
Many pests can also cause dry leaf tips 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 dry tips
Besides diseases and insect pests causing dry tips in Welsh onions, improper practices in daily management can also cause dry tips. When Welsh onions lack calcium or boron, their growth and development are hindered, leading to withered leaves and dry tips. A lack of water in the plants can also cause dry tips; using pesticides at too high a concentration can also cause the leaves to turn white or develop dry tips.
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; the concentration should not be too high, and after pesticide damage occurs, promptly spray a remedy.
The above is an introduction to the causes of dry leaf tips in Welsh onions and the control measures. We hope it helps you. To learn more related knowledge, please follow us.