blossom-end rot 番茄烂底病防治

Awater-soaked spot at the blossom end of tomato fruits is the classic symptom of blossom-end rot. This relatively common garden problem is not a disease, but rather a physiological disorder caused by a calcium imbalance within the plant. It can occur in pepper, squash, cucumber, and melon fruits as well as tomatoes. 这不是一种病，更应该是由钙不平衡引起的症状。也可发生在青椒辣椒，西葫芦，黄瓜和甜瓜。

Blossom-end rot is most common when the growing season starts out wet and then becomes dry when fruit is setting. Damage first appears when fruits are approximately half their full size. The water-soaked areas enlarge and turn dark brown and leathery. These areas will eventually begin to rot, so the fruit should be picked and discarded. 受损果实应摘下丢弃。

Several factors can limit a plant’s ability to absorb enough calcium for proper development. These include: fluctuations in soil moisture (too wet or too dry), an excess of nitrogen in the soil, root damage due to cultivation, soil pH that’s either too high or too low, cold soil and soil high in salts。以下措施可提高钙摄取：
 

• Maintain consistent levels of moisture in the soil throughout the growing season. When the weather is dry, water thoroughly once or twice each week to moisten the soil to a depth of at least 6 inches. 在生长季节保持适当土壤湿度
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• In cold climates, allow soil to warm before planting; cold soils limit nutrient uptake. 当土壤温度提高后才定植，否则会影响营养摄取
• Maintain soil pH at or near 6.5. 保持PH在6.5左右，可以通过补充石灰，ground limestone
• Use fertilizers that are low in nitrogen and high in phosphorous, 所用肥料应该含氮低，含磷高
• Apply mulch to minimize evaporation and help maintain consistent soil moisture. 适当覆盖土壤，减少蒸发，提高湿度
• Keep garden records: You may discover that some crop varieties are more susceptible to blossom-end rot than others 选择抗病品种