Is there a plant doctor in the house?

摘要

In last month's article, we talked about temperature, moisture, inadequate oxygen, light and air pollution as environmental factors that might cause plant diseases. In this article, we are going to talk about nutritional deficiencies and toxici-ties as environmental factors that might cause plant diseases. Plants require several mineral elements for normal growth. Some elements, such as nitrogen, phosphorous, potassium, calcium, magnesium and sulphur needed in relatively large amounts, are called 'major' elements, while others, such as iron, boron, manganese, zi'nc, copper and molybdenum needed in small amounts, are called 'trace' or 'minor' elements, or micronutri-ents.