Harmful symptoms and prevention of pumpkin leaf spot

Pumpkin is a plant of the genus Cucurbitaceae. The term "pumpkin" can specifically refer to Chinese pumpkin (Cucurbita moschata) in the genus pumpkin, and can also generally refer to other cultivated species of pumpkin, including bamboo squash (also known as Indian pumpkin), zucchini (also known as American pumpkin) and so on. Among them, the former is called "North melon" in Changde and other places in Hunan, and it is also called "North melon" in Changde, Hunan Province, and is also called "North melon" in Changde, Hunan Province, and is also called "North melon" in Changde, Hunan and other places. Pumpkins are planted all over China. The tender fruit is palatable and is one of the melons and vegetables in summer and autumn.

Pumpkin has good cultivation characteristics and strong adaptability to environmental conditions, so it is widely cultivated all over the world. According to the statistics of the Food and Agriculture Organization of the United Nations, pumpkin ranks ninth in the output value of different vegetable crops in the world, with an annual sales value of 4 billion US dollars. China and India are the two main pumpkin producing countries in the world, of which China's cultivated area ranks second in the world and its total output ranks first in the world.

The beneficial ingredients of pumpkin to human body are: polysaccharides, amino acids, active protein carotenoids and a variety of trace elements. The functions of various ingredients:

1. Polysaccharides: pumpkin polysaccharide is a non-specific immune enhancer, which can improve the immune function, promote the production of cytokines, and regulate the immune system by activating complements.

2. Carotenoids: the rich carotenoids in pumpkin can be converted into vitamin A with important physiological functions, which has important physiological functions for the growth and differentiation of epithelial tissue, maintaining normal vision and promoting the development of bones.

3. Mineral elements: pumpkin is high in calcium, high in potassium and low in sodium, which is especially suitable for middle-aged and elderly people and patients with hypertension, which is helpful to prevent osteoporosis and hypertension. In addition, it also contains phosphorus, magnesium, iron, copper, manganese, chromium, boron and other elements.

4. Amino acids and active proteins: pumpkins contain a variety of amino acids needed by the human body, including lysine, leucine, isoleucine, phenylalanine, threonine and so on. In addition, the genotype of ascorbate oxidase in pumpkin was the same as that in tobacco, but the activity of ascorbate oxidase in pumpkin was significantly higher than that in tobacco, indicating that the content of immunoreactive protein in pumpkin was higher.

Harmful symptoms and prevention of pumpkin leaf spot

The harmful symptoms of pumpkin leaf spot disease are mainly harmful leaves. At first, there were small brown spots in the shape of water, and a yellow halo was seen around the spot through the sun. After the plaque is enlarged, the central part is easy to break, through the wind and rain, full of small holes.

The conditions for the occurrence of pumpkin leaf spot were as follows: the optimum temperature for development was 25 ~ 30 ℃, and the pH value was 5.8 ~ 9.0. The pathogen overwintered with the remains of the diseased plant in the soil, forming the primary source of infection in the coming year, or transmitted through seeds.

Preventive measures: the seeds should be treated with dry heat at 70 ℃ for 3 days. Do not bring in the diseased seedlings, which usually begin to occur from the end of April to May and spread after rain. After poor drainage and rainfall or flood irrigation, the disease is more serious. Be careful not to let water droplets stay on the leaves for a long time to prevent water from contributing to the spread of the disease.