Symptoms and Causes of Tomato Stems and Rotten Fruits

Symptom identification: tomato tendon rotten fruit is commonly known as "black tendon". There are two obvious types: browning gluten rotten fruit and whitish gluten rotten fruit, of which browning tendon rotten fruit is the most common. Browning tendon rotten fruit: the young fruit began to occur, mostly in the lower part of the plant, in the fruit expansion period, the fruit surface was unevenly colored, and then local browning occurred. When the fruit was cut, the vascular bundles in the pericarp were dark brown or tea-brown. In the lightly diseased fruits, part of the vascular bundles turned brown and necrotic, and the shape of the fruits did not change, but the browning parts of the vascular bundles did not turn red; in the severely diseased fruits, the vascular bundles of the pulp were all dark brown, and the fruit surface was uneven and unedible. White deformed tendon rotten fruit: from the green school to the turning red period, the color of the fruit is poor, the red part of the fruit decreases in appearance, the diseased part has waxy luster, the cut fruit shows the shape of "bran heart", and white or brown ribs appear in the pericarp and the middle ribs next door. The flesh of the diseased fruit is hardened and the quality is poor. Tendon rot usually occurs only on fruits, and there are no obvious symptoms in stems and leaves. When seriously ill, sometimes the top and lower leaves of the plant are curved, and the middle ribs of the leaflets are protruding. When the stem of the plant was cut 70 cm from the root, brown lesions could be seen in the conducting tissue of the stem.

Etiology: the cause of tomato tendon rot is very complicated. preliminary analysis shows that the deficiency of carbohydrates and the decrease of carbon-nitrogen ratio in tomato plants lead to metabolic disorders, resulting in vascular bundle Lignification is the direct cause of the disease, and many adverse environmental conditions. such as lack of light, low temperature and humidity, poor air circulation, insufficient carbon dioxide, high night temperature, low ground temperature, excessive soil moisture and so on. All of them will cause the deficiency of carbohydrates in the plant. Partial and excessive application of nitrogen fertilizer, especially excess ammonia nitrogen, potassium deficiency, boron deficiency and other trace elements will also reduce the ratio of carbohydrate to nitrogen in the plant. In addition, too much irrigation, moist soil and poor permeability will hinder the absorption of nutrients by tomato roots, lead to the loss of nutrient balance in the plant, hinder the absorption and transfer of iron, and are also the reasons for brown gluten rot. For example, in 2005, several greenhouses in Tieling Village, Mucheng District, due to low-lying terrain, close to the riverside, poor drainage in the greenhouse, heavy soil viscosity, and plants could not absorb nutrients, resulting in browning of young tomato fruits; in the autumn of 2006, a greenhouse in Lixin Village was planted too densely, leaving too many fruits, fruits competing with each other for nutrients, and some tomato fruits were unevenly colored and the pulp turned brown. The cause of white gluten rotten fruit is related to the above, but it is mainly due to the toxin produced by tobacco mosaic virus infection.