Study on the diseases of the hottest grape during

Research on grape storage diseases

in recent years, with the continuous increase of grape planting area and the introduction of some late maturing and storable varieties, the yield has also increased year by year. In the past, grapes were mostly eaten directly and directly entered the circulation field. However, with the continuous increase of production, the contradiction between production and marketing of grapes is becoming more and more prominent. Therefore, how to prolong the preservation of grapes has become a very urgent topic. Disease is one of the main problems affecting grape storage and preservation. At present, there is little research on this aspect at home and abroad. In order to provide a basis for the prevention and control of grape storage diseases, the author made a detailed investigation and Research on the occurrence of low-temperature storage grape diseases from 2001 to 2002. Now the results are reported as follows:

1, test materials and methods

1.1 test varieties. The test varieties are late maturing high-quality red and black globe grapes, which are produced in the agricultural industry demonstration park of Jingyang County, Shaanxi Province

1.2 isolation and identification of grape pathogenic bacteria take the diseased fruit of grapes with different symptoms, put it into small pieces of chening at the junction of disease and health, disinfect it, inoculate it on PDA culture medium respectively, culture it in 25 ℃ incubator, and pick out single hypha for purification two days later. Connect the isolated and purified strain to the plate culture medium, and conduct microscopic examination after mycelium and spore are produced

1.3 the pendulum position of grape disease adjustment during storage is abnormal. Check the tested materials red and black globe grapes, 5kg per bag, storage temperature 0 ℃, and put grape preservative and absorbent paper in the packaging bag. Before storage, 30 days, 70 days and 120 days after storage, the types of diseases and the degree of damage were investigated respectively. During the investigation, 100 seeds of each variety were randomly selected, and the number of affected fruits was counted, repeated for 3 times, and the incidence rate of various diseases was calculated

1.4 relationship between pathogen growth and external factors

1.4.1 relationship between pathogen growth and temperature different pathogens isolated and purified from diseased grapes were inoculated on PDA medium and cultured at 0 ℃, 3 ℃, 8 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃ and different temperatures respectively. The growth rate of colonies was observed, and the diameter of colonies was measured and recorded every day

1.4.2 relationship between the growth of pathogenic bacteria and pH value adjust the pH value of the medium with lactic acid and sodium carbonate, test with precision pH test paper, adjust the H value of P to 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 respectively, inoculate after sterilization, place it in a 25 ℃ incubator for culture and observation, and measure and record the colony growth diameter every day

2, results and analysis

2.1 isolation results grape storage diseases were isolated and identified, mainly gray mold, root mold, Penicillium, etc

(1) gray mold the pathogen of the disease is Ascomycetes, lepidomycetes, sclerotiniaceae, botrytisd Nerea, the sexual generation is botrytinia fuekeliand (Debary) whetzel, and the conidia of [botrytinia fuekeliand (Debary) whetzel] are oval or oval. The sclerotia is black and irregular in shape. The sclerotia is slightly smaller than that of Botrytis cinerea of cucumber. Botrytis cinerea has occurred on grapes for three times, the first is the young fruit stage after falling flowers, the second is the fruit ripening stage, and the third is the grape storage period. In the early stage of storage, the symptoms of grape fruit disease are that there are round concave disease spots with a diameter of 2 ~ 3 on the peel, and the color of the disease spots is slightly lighter than the surrounding normal tissue. If you gently press the disease spots with your hand, the epidermis of the disease spots will rupture, exposing the pulp. In the late stage of disease, the disease fruit will be soft and rotten, and a gray mold layer (i.e. pathogenic mycelium) will be produced on the disease fruit, a large number of conidia and spores will be produced on the mycelium, and even a small amount of sclerotia will be produced on the fruit, Finally, the fruit completely loses its commodity value

(2) Rhizopus the pathogen of this disease is algae, Mucor, Mucor family, Rhizopus [rhizopu because of its different structure s nigricans Ehrenb] produces white aerial hypha in PDA medium, the hypha is bow shaped, and soon produces black entities on the top of the hypha. Pseudoroots are produced at the contact of the substrate. The pseudoroots are developed, with many branches, brown, and the cyst stalk is upright and unbranched. Rhizopus mainly damages the cob shaft, fruit stalk and fruit during grape storage, and the pathogen mostly invades from the wound. At the initial stage of the disease, the disease spots were waterlogged, and the affected parts became soft, but soon grew white long hairs, and the affected fruits were easy to fall off the fruit stems. If the grapes are taken out of the cold storage, coarse mycelium will be produced in the affected part and many brown fruiting bodies will be formed, and the grapes will rot quickly

(3) penicilliosis the pathogen of this disease is plexus territoriales, plexus territoriaceae, Penicillium, fingered Penicillium Group [CE] on PDA culture, the colony is fluffy; At first, it is white, then it becomes olive green, with dark brown on the back. The conidia stalk is short, broom like branches, large and irregular, and the conidia are oval to cylindrical. The spores are powdery, so once individual fruits are infected, they will soon infect other fruits

after the fruit is infected with Penicillium, discolored circular or semicircular concave spots are formed on the fruit, gradually turning dark yellowish green, and finally turning olive green. The peel shrinks, the fruit softens, and the pulp turns into a transparent paste. Rotten tissue has a musty smell

2.2 disease damage during storage. The red and black globe grapes stored in cold storage were investigated before storage, and there were no obvious symptoms, and the incidence rate was 0; After storage for 30 days, the incidence rate of gray mold, root mold and Penicillium were 7.32%, 2.57% and 0.03%, respectively; The investigation after 70 days of storage showed that the incidence rate of gray mold was 16.51%, the incidence rate of Rhizopus was 11.62%, and the incidence rate of penicilliosis was 0.56%; 120 days after storage, the incidence rate of gray mold was 31.48%, the incidence rate of Rhizopus was 17.82%, and the incidence rate of penicilliosis was 1.02%

2.3 relationship between pathogen growth and temperature. The mycelium of Botrytis cinerea can grow normally in the range of 3 ℃ ~ 30 ℃, and the optimal growth temperature is 15 ℃ ~ 25 ℃. When the medium is artificially inoculated at 0 ℃, the colony diameter is only 0.12cm after 16 days of inoculation, and the mycelium grows slowly. The figure shows the mycelium growth of Botrytis cinerea in 4 days at 3 ℃ ~ 30 ℃

Rhizopus mycelium can grow normally in the range of 5 ℃ ~ 30 ℃. The optimal growth temperature is 15 ℃ ~ 30 ℃, and the mycelium grows slowly at 0 ℃ ~ 3 ℃. At 0 ℃, only a small amount of mycelium grows after 28 days of artificial inoculation on the medium, and at 3 ℃, the colony diameter is only 0.1cm 6 days after inoculation. The figure shows the mycelium growth of Rhizopus in 2 days at 3 ℃ ~ 30 ℃

penicilliosis can grow at 3 ℃ ~ 30 ℃, and the optimal growth temperature is 15 ℃ ~ 25 ℃, and the mycelium of penicilliosis grows very slowly in the range of 0 ℃ ~ 3 ℃. At 0 ℃, only a small amount of mycelium grows after 32 days of artificial inoculation on the medium, and at 3 ℃, the diameter of the colony on the 8th day after inoculation is only 0.11cm. The figure shows the colony growth of penicilliosis in 4 days at 3 ℃ ~ 30 ℃

2.4 in order to meet the measurement requirements of different experimental loads, the test results showed that Botrytis cinerea could grow at pH5 ~ 10 during grape storage, the optimal pH was 5 ~ 7, PH9 ~ 10, the mycelial growth rate slowed down with the increase of pH, and alkalinity had an inhibitory effect on Botrytis cinerea. Rhizopus can grow in the range of pH5 ~ 10, and alkalinity has no significant effect on the growth of Rhizopus

3. Summary and discussion

Baosteel's share in grape storage period is expected to increase by 600% to 800% throughout the year. The disease is serious and the symptoms are complex, which is caused by the combined infection of several fungi. Among them, gray mold is the most serious, followed by root mold, and Penicillium is the least harmful. With the extension of grape storage period, the occurrence of disease is on the rise. The serious occurrence of diseases restricts the development of storage industry

red and black grapes are late maturing varieties. Generally, they are harvested late, and a large number of bacteria are hidden on the fruits, and the berries have high sugar content. Although the temperature of grapes during storage is low, the pH value of berries during storage is under acidic conditions, and the air humidity of microenvironment during storage is high, creating favorable conditions for the occurrence and spread of various diseases

source: Farmer Education