Thai ruby grapefruit main pest occurrence law and control technology
Yang Aifang
Thai grapefruit is generally a short ball shape, its outer skin color is cyan, the flesh color is red, and its taste is soft and juicy, very fresh and sweet, and because of its low acidity, it is also known as "grapefruit". Thai grapefruit has strong adaptability, high survival rate, relatively loose planting conditions, in the low temperature, soil pH 4.8 ~ 8.5 mountain, slope can be planted. In addition, Thai grapefruit also has high economic value and nutritional value, not only can make essential oils and pectin, but also rich in vitamins, caribrin, calcium, magnesium, potassium, sodium and other components, can meet people's nutritional needs.
1 Analysis of the occurrence of major diseases of grapefruit and prevention and control measures
1.1 Anthrax
1.1.1 Occurrence of symptoms and regularities
Anthrax is one of the common diseases in the cultivation process of grapefruit, which is a fungal disease, which mainly causes different degrees of decay and fall of the branches, branches and fruit parts of grapefruit. 1) From the perspective of the harm of anthrax to grapefruit leaves, it can be divided into two types according to the different symptoms of grapefruit leaf pathogenesis. Leaf spot type disease is mainly in the old leaf tip or leaf margin appear irregular and concave spots, thereby affecting the growth and health of grapefruit tree, its evolution law is the initial spot in the middle of the gray-white, the outer ring is yellow-brown, and then gradually appear in the site of the disease some black particles. Leaf blight mainly occurs at the main vein of the new leaf to the tip of the leaf, and its evolution law is the initial appearance of dark green irregular spots, with the development of the disease, the color of the spots gradually becomes yellowish, and the leaves will gradually rot and wither. 2) From the point of view of the harm of anthrax to the branches of grapefruit, it is mainly gradually spreading from the top of the branches to the surroundings, and on the branches at the beginning of the disease, the color of the spots is pale yellow, and the branches in the later stage gradually appear gray and white, and dry and forked. 3) From the perspective of the harm of anthrax to grapefruit fruit, the disease site of the fruit is generally at the fruit peduncle, and the fruit rots due to the gradual spread of the initial brown spots. 4) As far as the occurrence law is concerned, the pathogen of the disease mainly overwinters on the diseased branches and fruits in winter, and spreads by wind or diseases and insects in the spring.
1.1.2 Prevention and control techniques
When planting personnel prevent and control grapefruit anthrax diseases, they can mainly use the following 3 control methods: 1) do a good job in the daily management of the grapefruit park, ensure the ventilation and light transmission of the grapefruit growth environment, and prune the grapefruit tree in time to reduce the disease branches and prevent the spread of diseases; 2) to do a good job in the fertilizer management of the grapefruit park to improve the disease resistance of the grapefruit tree itself; 3) After the grapefruit fruit is picked, it is necessary to carry out antiseptic treatment in time, and the fruit tree can be sprayed with carbendazim, thiamethoxam and other agents.
1.2 Scabs
1.2.1 Occurrence of symptoms and regularities
Scab disease is also one of the most influential diseases in grapefruit cultivation. Scab disease, also known as hemp shell, mainly affects the young branches, shoots and young fruits of grapefruit. 1) When the grapefruit leaves have scabs, oily spots will appear on the leaves, and with the expansion of the spots, the phenomenon of leaf perforation, deformation and shedding will gradually appear, and it will have a serious impact on the growth of young fruits, so that the growth of young fruits will be deformed and the quality will decrease; 2) when the young branches of grapefruit scabs occur, there will be the phenomenon of wood peg uplift, and the branches will gradually deform and shorten; 3) When the young fruits of grapefruit have scabs, the surface of the fruit will gradually become rough, and nodular protrusions will occur, and the problem of early fall will occur 4) Scab disease is a fungal disease, the pathogen belongs to the subphylum semi-known bacteria, which mainly overwinters on the leaves of grapefruit in winter, and when the temperature rises in the spring, the diseased area of grapefruit will be mesmerized with diseased spores, and then spread to a wider range with the help of wind and rain.
1.2.2 Prevention and control techniques
In the prevention and control of scab diseases, there are two main types of prevention and control methods: agricultural control and chemical control. In agricultural prevention and control, planters should do the following 2 points: 1) Before planting, pay attention to the selection of grapefruit seedlings, not only to select seedlings with high yields, but also to select seedlings with strong disease resistance and adaptability, and at the same time do a good job in disinfection and inspection of seedlings, and prevent and control diseased seedlings entering the orchard; 2) During the winter planting management of grapefruit, it is necessary to do a good job of pruning work, and timely pruning and incineration of some diseased branches and diseased leaves, thereby reducing the probability of disease occurrence. As far as chemical control is concerned, it is mainly sprayed with chemical agents for spray control, and in the early fruit stage of grapefruit, 50% carbendazim wettable powder 1 000 times liquid is sprayed all over the treetops, and the number of sprays can be determined depending on the occurrence of diseases.
1.3 Ulcer disease
1.3.1 Occurrence of symptoms and regularities
Canker disease mainly affects the leaves, treetops and fruits of grapefruit, but unlike grapefruit scab disease, it does not cause deformation of leaves and fruits when it occurs, and its infection site is still normal size. 1) When the canker disease is harmful to the leaves of grapefruit, the back of the leaves first changes, and many small yellow-green spots appear, and with the continuous spread of the disease, the leaf surface appears bulging, the spots expand, the color becomes darker, and the leaves crack; 2) When the canker disease is harmful to the grapefruit treetops, there will also be needle-tip spots at first, and then gradually bulge, and finally cause the treetops to wilt; 3) When the canker disease is harmful to the grapefruit fruit, it will cause the early fall of the fruit and the wood bolting, and compared with the disease spots at the leaves and leaf tips, The shape of the fruit spots is larger, and there are more cracks; 4) In terms of the pathogenesis of canker disease, canker disease is a bacterial disease, and its germs are often hidden in the leaves, shoots and fruits of grapefruit for winter, and gradually erupt in high temperature, typhoon, rain and other weather the following year.
1.3.2 Prevention and control techniques
In the prevention and control of grapefruit canker disease, the following four methods can be mainly used: 1) the planting personnel should do a good job in the quarantine and disinfection of the seedlings in order to prevent the invasion of the disease from the source, it is strictly forbidden to bring diseased seedlings into the park, and strictly disinfect the treatment; 2) the planting personnel should strengthen the management and cleaning work during the planting of grapefruit, and clean up the dead leaves and branches dropped in the park in time; 3) the planting personnel should do a good job in fertilization work to ensure the nutrient needs of grapefruit growth, and can reasonably increase K and P fertilizer 4) When using chemical means to prevent and control grapefruit ulcer disease, the planter should pay attention to the spraying time and frequency of chemical agents, mainly in the three stages of grapefruit new shoot bud budding, leaf greening stage and flowering stage, of which the optional agents are daisen ammonium water agent, Bordeaux liquid, cuproamine mixture and so on.
2 Analysis of the occurrence of major pests in grapefruit and control measures
2.1 Red Spider
2.1.1 Occurrence of symptoms and regularities
Red spiders, belonging to the order Tick mites, leaf mites, are one of the common mite pests in grapefruit cultivation. 1) Pest time: Red spider insect pests are mainly prone to outbreak in the dry season, and their common occurrence time is from February to May of each year, and the disease gradually decreases after the rainy season; 2) the pest site: the red spider mainly eats the leaf buds and fruits of grapefruit; 3) The symptoms of harm: the leaf surface that has been eaten by the red spider will appear gray-white mottled patterns, and its leaves will gradually turn yellow and fall off, and the growth of grapefruit trees will be seriously affected, so that its yield will be seriously reduced.
2.1.2 Prevention and control measures
In the control of red spider diseases, there are mainly the following 2 kinds of control measures: 1) winter is the first high incidence of red spider disease, planters should do a good job of cleaning up the eggs of red spider insects, to prevent the eggs from overwintering, generally can use stone sulfur spray or 20% g mite enemy 2 000 times liquid to eliminate overwintering eggs; 2) summer is the second high incidence of red spider diseases, which can be sprayed for control with arvil mite ester.
2.2 Thrips
2.2.1 Occurrence of symptoms and regularities
Thrips are a collective term for the insect order Tamarind and are one of the common pests in grapefruit cultivation. Thrips are commonly brown or black, and their mouthparts are filed to suck, which can break the epidermis of plants and suck up sap, which has a serious impact on the branches and leaves of grapefruit, flowers and fruits. Thrips can occur all year round, causing the deformation and shedding of grapefruit leaves, which will weaken the growth of grapefruit and seriously affect the production quality of grapefruit.
2.2.2 Prevention and control measures
Growers can take the following control measures when carrying out grapefruit thrips pest control work. 1) Agricultural control: planters can reduce the harm of thrips to grapefruit trees through pruning and fertilizer management; 2) physical control: planters can use the blue and yellow habits of thrips to booby trap; 3) chemical control: planters can use conventional agents such as imidacloprid and acetamiprid for control.
2.3 Leafminer moths
2.3.1 Occurrence of symptoms and regularities
Leafminer moths, belonging to the Lepidoptera leafminer moth family, generally occur in April to October of each year. In grapefruit cultivation, leafminer moth larvae will feed on grapefruit leaf flesh, which will seriously damage the grapefruit tree and make grapefruit more susceptible to scabs, ulcers and other disease problems.
2.3.2 Prevention and control measures
When planting personnel carry out leaf-leaving moth pest control, there are mainly the following four kinds of control measures: 1) unified release of shoots, eliminate insect sources, and prevent the spread of diseases; 2) strengthen pruning and concentrate on cleaning up miscellaneous branches; 3) use the phototropism of diseases and insects to booby trap; 4) spray dichlorophenoxymethrin, insecticide dihydrotide and other agents for insect pest killing.
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3 Conclusion
In the cultivation of grapefruit, the relevant planters should do a good job in the prevention and control of grapefruit diseases and insect pests, and according to the occurrence of common diseases and insect pests, do a good job of relevant coping strategies, so that diseases and insect pests can be prevented and treated in a timely manner, so as to reduce their impact on grapefruit yield and quality, so that the grapefruit planting industry can get better development.