In recent years, with the extension of the age of jujube trees and the continuous expansion of cultivated area, the area of ​​shrinkage disease has been increasing, and the degree of damage has become more and more serious, causing large areas of jujube fruit to fall off, reducing production by 30%-0%. This article gives a detailed summary of the occurrence period, symptoms, causes and prevention measures of jujube fruit disease for your reference.
1. The period of occurrence
According to observations and studies in recent years, the initial stage of shrinkage disease in Linyi County is mid-June, that is, the rapid growth period of jujube fruit longitudinal diameter (longitudinal length 1.0-1.2cm, transverse diameter 0.9-1.0cm). The occurrence period is mid-July, that is, the jujube nucleus is formed to the rapid growth period (the length of the longitudinal diameter is 2.3-2.8 cm, and the transverse diameter is 1.2-1.5 cm). The end of the period is mid-August.
2, symptoms occur
2.1 burning eggplant
In the young fruit stage, yellow-brown lesions appear in the middle of the initial fruit surface, and the lesions continue to expand. The end of the fruit stalk is spread to the lower part, and finally the upper and lower thick reddish-brown sticks are like the eggplant fire.
2.2 waist
After the fruit is damaged, there is a pale yellow water-immersed spot on the waist, and the edge is clear. Afterwards, the disease point is continuously enlarged, and it develops around the middle of the jujube fruit, from yellowish brown to dark brown, and the middle part is slightly hollowed into a bee waist. Some of the diseased fruits began to form yellow-brown stripes from the stalks to the concave and concave parts. The arrangement was relatively neat. The peeled peels were yellow-brown, the corpuscles were soft and spongy, and the tissue was necrotic. It continued to expand deep into the flesh, and tasted bitter afterwards. The fruit is dehydrated, the skin shrinks and shrinks, and sometimes the fruit is dehydrated. The longitudinal shrinkage pattern appears on the side of the jujube, the depression is reddish brown, the date stem is brown, and the jujube fruit falls off.
3, the cause
The main cause of shrinkage of jujube trees (especially pear jujube) is the combination of nutrient deficiency and physiology, and the incidence of pathogen invasion is a secondary factor. The specific reasons are analyzed as follows.
3.1 Less fertilization, insufficient nutrient
According to the survey, 50% of the jujube trees have a base fertilizer of 0.35-0.70kg, or no base fertilizer, and the plant has a topdressing weight of 0.35-0.70kg. The management is good, and the stable growth rate of the jujube garden is about 5%. 25% of jujube farmers do not apply base fertilizer, plant topdressing only 0.1kg, 1-2 times of fertilization, poor management of growth period, weak tree, average fruit rate of shrinkage fruit disease 40%-55%, the highest disease fruit The rate is 67%.
3.2 excessive nitrogen fertilizer, nutritional imbalance
According to the survey, the jujube garden without applying the base fertilizer was filled with manure and urine twice during the growth period of the jujube tree, and the urea was chased once (150 kg/hm2), and the fertilization was applied once, and the fruit rate of the fruit reduction was 47.5%. The main reason is that the nitrogen fertilizer is too much, the growth of branches and leaves is too strong, and the amount of boron required for jujube trees is correspondingly increased, causing boron deficiency. At the same time, excessive nitrogen fertilizer and boron fertilizer are rejected, which directly affects the normal development of jujube fruit. The jujube fruit is small and the resistance is weak, which leads to the occurrence of shrinkage disease.
3.3 Large load, insufficient nutrient supply
According to the survey, the growth conditions of the two trees in the same jujube garden are basically the same, one of which has a small load, the fruit rate of the fruit shrinkage is 4.65%; the rate of fruit shrinkage of another strain is 22.1%. .
3.4 Impact of climatic conditions
Generally, in high temperature and dry years, boron is not easily absorbed by the roots of jujube trees, and it is not easy to transfer in the tree body, causing the lack of boron in the fruit, which often aggravates the occurrence of shrinkage. Under the conditions of basically the same temperature, the rainfall is large and light occurs; the rainfall is small and the weight is heavy. The jujube garden with dense branches and a large number of jujube fruits is more serious than the jujube garden with scattered branches and good ventilation and light transmission; the jujube garden with direct sunlight, the shrinking fruit disease is more serious than the jujube fruit in the ventilation and shade space. Different varieties have different sensitivity to boron and different degrees of contraction. Pear jujube is highly sensitive to boron, and the incidence is heavy. Mango winter jujube is sensitive, and Zhanhua winter jujube is less sensitive.
4, prevention measures
4.1 Agricultural measures
First, the selection of disease-resistant varieties. Early-maturing varieties that are not sensitive to shrinkage diseases such as Zhanhua Dongzao, Pingzao, and June Fresh can be used. The second is to plant the direction. Planting things in the east and west, avoiding the hot summer direct sunlight from 13:00 to 15:00, reducing the occurrence of shrinkage. The third is cultivation management. Timely thinning and reducing load. Grab the topping and trimming, which is conducive to the ventilation and light transmission of the jujube trees, and pay attention to the upper and lower layers to create a cool and light microclimate, reducing direct sunlight. During the high temperature and drought in June and August, the number of watering is determined according to the weather conditions, the water solubility of the fertilizer is increased, the fertilizer is reduced, and the water requirement of the jujube fruit is satisfied. At the same time, various organic fertilizers are added. In the autumn or early spring, the plant is applied with 15g of boron fertilizer and 1-2kg of diammonium phosphate in summer.
4.2 Chemical control
Before the germination of the jujube tree, spray with 2%-3% borax + 40% chlorpyrifos 800 times. When the jujube tree blooms about 30%, it is sprayed with 0.3%-0.5% borax or gibberellin + Aifuding No. 2 emulsifiable concentrate 5000 times, sprayed once every 7 days, and sprayed twice. Young fruit expansion period (from mid-June to late July), using 10% Shigao WP 1500 times solution + agricultural streptomycin 4000 times solution, or Ningnanmycin 600 times solution + Boron calcium 1500 times solution + Ai Fuding No. 2 emulsifiable concentrate 5000 times liquid + Kung Fu 2500 times liquid spray prevention, sprayed once every 7-10d, concurrent treatment of shrinking fruit disease, anthracnose disease, black spot disease and blind spot.
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