The fungal diseases during storage of lemon fruits mainly include black rot, acid rot, peduncle, blue and green mildew, and anthrax. Physiological diseases mainly include dryness and edema.
(1) Pelvic rot: Divided into two categories: brown pedicel and black pedicel. Symptoms are similar, but there is no obvious boundary between brown pedicel lesions and healthy tissues. There is a clear distinction between black spot and healthy tissue, and there is a bad smell in the later period. The bacteria invaded the fruit tissue from the fruit pedicle. The initial lesions were water-stained. The lesions continued to expand and gradually turned brown or black. The speed of rot passing through the center of the fruit was faster than that along the skin. It is particularly severe in rainy and humid production areas or years.
(2) Black rot: The first symptom is that the fruit pedicle is darkened, and the germs develop along the column in the fruit. Whereever the mycelium goes, it turns black and decays. During the growth and development of fruits, black rot pathogens are mostly present in the fruit pedicle, and they cannot invade the interior of the lemon tissue until the pedicle tissue is destroyed. Any condition that debilitates the fruit such as uncomfortable environment, late harvesting or long-term storage will increase the sensitivity of the fruit to black rot.
(3) Green mold: It refers to two kinds of storage diseases caused by Penicillium and Green mold. The pathological process and symptoms are similar. In the early stage, the surface of the skin became soft and water stain spots appeared. The white mycelium was changed to the blue or green mildew layer with the disease of the disease. The disease began to rot to the whole fruit. Take 1-2 weeks. The germs contact with the conidia or spread with the airflow. From the invasion of wounds and rips, the most fundamental preventive measure is to reduce mechanical damage. Green and green mildew are the most common causes of post-harvest decay in all commercial citrus regions of the world.
(4) Acid rot: The initial symptoms are water-stained yellowish-yellow spots with micro convexity. The pathogens grow mainly in the fruit. In the later period, the internal tissues of the fruit are all decomposed into water-like pastes with acidity. At 24-29°C, it took only 5 days from infestation to full fruit rot. Adjacent fruits were also exposed to infection, and the bacteria invaded from the wound.
(5) Anthrax: The onset begins at the tip of the pedicle, and the first external symptoms are gray to brown spots, after which the spot rapidly expands, sometimes extending to the entire fruit. In wet conditions, pink spores appear on the surface, and the spore colonies turn brown to black later, until late pathogens invade the deep flesh. The main infection is broad-leaved oranges, with occasional occurrence of lemon fruit, and severe disease in wet areas and years. The germs grow on the dead branches or weak branches of the orchard, and spread from there to the fruit, through the break in the peel or the dead fruit pedicle into the fruit.
Control methods for the above diseases: In addition to post-harvest treatments, drugs can be used for prevention and treatment. Methods as below:
1 thiabendazole (Tektronix, TBZ) and benzoyl (benzofen): is the most effective post-harvest bactericide, which can effectively control peduncle and blue and green mildew and has an effect on anthrax. However, it is not effective against acid rot and black rot. Both of these bactericides are slightly soluble in water, and they are usually used as a wax-water mixture or a suspension of water. The turbidity must be continuously shaken during the treatment in order to ensure that the liquid is uniform. The concentrations used were thiabendazole 1 000 mg/L, Benzol 600 mg/L, and fruit picking for 3-5 minutes.
2 Sodium Ortho-Phenylphenol (SOPP): It can control pediculosis and green and green mildew. It also has a certain effect on acid rot, especially for oranges. The use of a 2% aqueous solution of sodium o-phenylphenolate with a pH value of 11.5-12.0 is the highest, so the commonly used formula is: 2% sodium o-phenylphenolate + 0.2% NaOH+1% hexamine, also available 1% o-phenyl Phenol sodium wax solution.
3 sec-butylamine: can control the green and green mildew, is less effective on pedicle rot, acid rot and anthrax invalid. Sec-butylamine is a liquid and has a boiling point of 63°C. It can be used as a depot fumigant (25-200mg/L, V/V, 42h), and can also be formulated as a 1%-2% aqueous solution for fruit impregnation.
4 Biphenyl: It can control pedicel and blue and green mildew, and is not effective against acid rot. Is a vaporous fungicide. Commonly used method is: the permeability of the fruit pack paper by 2.35g: 1 sheet (27.9cm 43.2cm) in proportion with biphenyl impregnated to make Biphenyl fruit wrapping paper. Biphenyl can also be dissolved in paraffin oil (or mineral oil) made biphenyl - paraffin mixture, coated on paper to make biphenyl liner.
In China, currently used preservatives in production include thiophanate (1000-2000mg/L), carbendazim (800-1000mg/L), imazalil (500mg/L), sodium bicarbonate (2%), etc. .
Physiological diseases
(1) Brown spot (dry cockroach): Occurs mostly in the middle to late stages of storage. The initial symptoms are light brown irregular spots, after which the color becomes darker, the lesions expand, and at low temperatures develop an irregular ring-shaped spot centered on the pedicle. Lesions are broken at the lesions. The depression shrinks and the area is limited to the outer skin. Most people think this is a kind of physiological disease with low temperature disorder (Brooks & Mccolloch1936; Li Peiwen, 1977). Stored at low temperature and low humidity, the disease is particularly serious. In order to control and reduce the incidence of brown spot disease, measures such as proper late harvesting, high humidity, low O2, and high CO2 to avoid low storage temperature were adopted on the storage.
(2) Edema disease: The initial peel becomes lighter, and there is an irregular, translucent water spot in the local skin. The food has a kerosene taste. After the illness is serious, the whole fruit is translucent water-like fruit, soft, easy to peel, and the food has a strong taste of alcohol. If it continues to be stored, it will be rotted by other pathogens. A large number of tests have shown that excessive storage of low temperature and poor ventilation can cause excessive accumulation of CO2, which can lead to edema disease. As long as any one of the two factors is present for a certain period of time, edema disease will occur, and when the two factors are present at the same time, the disease will occur earlier and more severely. Therefore, prevention and control of lemon fruit edema should pay attention to prevent excessive storage temperature or excessive fluctuations, while strengthening management, pay attention to ventilation.
Mobile Radiology Systems And Solutions
Mobile X Ray,Cabin Spiral CT,Cabin Xray Diagnose,Radiography Equipment CT
MinFound Medical Systems Co., Ltd , https://www.minfoundmed.com