Scab disease is a common fungal disease on citrus, mainly harmful to new shoots, leaves, under suitable conditions easy to fruit, causing early fall or late fruit surface leprosy, the fruit yield and quality have a greater impact.
According to the China Meteorological Network forecast, the next week will usher in continuous rainfall in the south, but the temperature is higher than in previous years, this warm and high humidity climate environment, very conducive to the outbreak of scabs epidemic, all fruit farmers and friends must pay attention to, grasp the key prevention and control nodes after the flower to the young fruit stage, reduce fruit damage.
Sick leaves of moss-type scab disease: the spots are small and dense, resembling moss; the diseased leaves are curled and deformed.
Warty scab disease leaves: the lesions are more independent, and one side is raised and one side is concave in the later stage, like a bull horn and a funnel.
Disease at the flowering stage to the young fruit stage: the petals fall rapidly, and the young fruit surface has brown spots, and if the disease is more serious, it will fall off.
Fruit of Moss-type scab disease: thick skin, dense lignification moss-like small spots on the fruit surface, mostly striped or banded distribution.
Fruit of wart-type scab disease: the fruit surface is uneven, the lesions are large, and the bulges are often accompanied by lignification.
(1) The pathogen of scab disease is citrus scab fungus, which overwinters on diseased leaves, diseased shoots and fruits with mycelium.
(2) In the spring of the following year, when the temperature is above 15 °C and the humidity is suitable, conidia can be generated from the original disease spots, which are spread by wind, rain and insects, and directly invade new shoots, young leaves or young fruits.
(3) Because pathogenic cells can secrete crust cystic cavity mycelium, the compound can produce a large number of reactive oxygen species and superoxide compounds at the affected site, resulting in rapid death of citrus cells, so the incubation period after the occurrence of scab disease is relatively short, generally only 3 to 10 days.
(4) The conidia produced by the new spot can re-infect the citrus tissue, and the citrus summer and autumn shoots are endangered.
Varieties: Oranges are the most susceptible to diseases, such as Nanfeng mandarin oranges are more serious, followed by citrus and grapefruit, sweet oranges and golden oranges are more resistant to disease; early maturing varieties have more serious diseases.
Degree of tissue maturity: scab disease usually only infects young tissues, and the period of new shoots, young leaves to pre-spread leaves, and young fruits after flowering is the most susceptible, and with the aging of tissues, the susceptibility rate will gradually decrease.
Climatic conditions: Pathogenic bacteria like medium temperature and high humidity environment, when the temperature exceeds 28 °C, usually do not occur, so the spring shoots to young fruit stage is the most serious stage of the disease throughout the year.
Environmental conditions: orchards with high density, poor ventilation and poor drainage conditions have a heavy incidence, such as scabs in orchards with water-based fields.
(1) Thoroughly clear the garden in winter and spring, cut off diseased branches and leaves, and combine the agent to reduce the pathogen base.
(2) Unified release of the shoots, timely spraying of phosphorus and potassium source reservoirs after the spring shoots spread leaves, to promote their old ripening, shorten the hazard period, and at the same time turn into functional leaves after the spring shoots mature, which is also conducive to fruit stability.
(3) Pharmaceutical prevention and control focus on grasping the three nodes of spring bud germination, flowering and young fruit stage, and can choose to win pole (75% oxime and pentazoliol dry suspension), protection + treatment, and prevent fungal diseases such as anthrax, sand skin disease, brown spot disease, etc., and it is safer for flowers and fruits. In addition, for the diseased tip should be cut in time, and centralized treatment, to prevent repeated infection, under normal circumstances, you can also add daisen manganese zinc to prevent disease, daisen manganese zinc in citrus more use, the effect is not bad.
This article is written and sorted by the agricultural assistant team, please be sure to indicate the source of the agricultural assistant, and do not modify the content of the article, the modification must be investigated!