Integrated Control of Diseases and Pests of Horticultural Crops

Haijuan ZHANG, Jingmin WANG, Fajiang GONG, Tao LU, Yujing ZHAO, Yaru ZHU, Dongwen SUN*

1. Zibo Digital Agriculture and Rural Development Center, Zibo 255000, China; 2. Zibo Academy of Agricultural Sciences, Zibo 255020, China; 3. Linzi District Agricultural Technology Service Center, Zibo 255499, China; 4. Shandong Agriculture and Engineering University, Jinan 250100, China

Abstract In view of the occurrence and aggravation of diseases and pests of horticultural crops, the management process should follow the basic policy of "prevention first, comprehensive control". Starting from the ecological system, agricultural, biological, physical and chemical means should be comprehensively applied to control diseases and pests below the economic injury level.

Key words Horticultural crops; Diseases and pests; Integrated control

1 Introduction

With the increase in cultivation years of horticultural crops, the occurrence of diseases and pests is increasing, which brings great impact to the production of horticultural crops. The management process should follow the basic policy of "prevention first, comprehensive control", and agricultural, biological, physical and chemical means should be comprehensively applied to control diseases and pests below the economic injury level.

2 Agricultural control

2.1 Breeding and utilization of resistant varietiesDifferent kinds and varieties of horticultural crops have great differences in their resistance to diseases and pests. Breeding and proper use of resistant varieties are the most economical and effective ways to prevent or reduce the occurrence and prevalence of diseases and pests.

2.2 Adopting reasonable cultivation system and reasonable layoutReasonable crop rotation can change or worsen the environmental conditions of diseases and pests, and play a role in interrupting and inhibiting transmission. The commonly used rotation methods are paddy-upland rotation, grain-vegetable rotation, grain-fruit rotation,etc.Reasonable crop layout can also play a controlling effect, for example, the use of varieties with different maturity periods can effectively avoid the epidemic period of diseases and pests.

2.3 Cleaning fields and intensive cultivationMost pathogens and pests survive the winter in soil or plant remnants. The number of pathogens and pests can be greatly reduced by intensive cultivation, eradication of pathogens and host weeds, timely removal, burying or burning intensively of diseased branches, diseased leaves, diseased fruits and weeds in the garden during the growing season and dormant season. Deep tillage and drying of the soil can cause pathogens and pests be frozen to death or die from exposure to the sun in winter.

2.4 Making full use of gardening facilitiesBy using the favorable conditions of high temperature in horticultural facilities and improving the environment, the target crops can germinate early and grow robustly, which will improve the resistance to diseases and pests, and reduce the damage degree of diseases and pests.

3 Biological control

Biological control is featured by safety, no pollution, no induction of resistance, and long-term control effect on some diseases and pests.

3.1 Utilization of parasitoids and predatorsThere are many species of parasitoids, and the most important ones are parasitic wasps and parasitic flies. The most common predators are mantis, flower bug, dragonfly, assassin bug, piercement bug, lacewing fly,etc.In addition, most spiders, birds, amphibians, reptiles, a few fish and mammals (hedgehogs, bats) are also important predators of pests.

3.2 Utilization of microorganismsThe phenomenon that one kind of microorganism can inhibit the growth and development or even digestion of another kind of microorganism is called antagonism.

3.2.1Antibiotic bacteria and antibiotics. A large number of microorganisms in soil are in a state of equilibrium. Artificial cultivation of antibiotic bacteria and application into soil can change the balance between soil microbial communities and achieve the purpose of controlling harmful microorganisms with beneficial microorganisms. Some antibiotics produced by fungi, bacteria and actinomycetes are used in the prevention and control of plant diseases and pests, such as streptomycin, kasugamycin, inner-iterapentic substance, tetracycline, griseofulvinum,etc., which have played a positive effect.

3.2.2Parasitic microbes. There are many microorganisms in nature that can cause insect diseases. More than 500 species of such fungi have been identified so far, for example, the use of bacteriophages that parasitize in bacteria and actinomycetes to control plant diseases, the use ofEmpusathat can infect aphids, locusts and flies, the use ofBeauveriaandMetarhiziumthat can parasitize in Lepidoptera, Coleoptera, Homoptera and mites, as well asAschersoniawith high virulence against whiteflies. There are more than 90 species of bacteria that can cause disease of insects. For example,Bacillusthuringiensis, which is widely used in production, can be used to control a variety of pests such asPierisrapae,Plutellaxylostella, pine caterpillar and scarab. There are more than 500 viruses that can infect insects, in which nucleopolyhedrovirus, granulosis virus and cytoplasmic polyhedrosis virus can soften the body tissue and rupture the body wall of the infected insect which will then discharge odorless turbidness liquid from the crack and die. Insect viruses are highly specialized and are safest to use.

3.3 Insect hormoneThe use of insect hormones to control pests is a new way of biological control. Currently, juvenile hormone and sex pheromone are widely used. The application of juvenile hormone in the late and pupal stages of larvae with very low levels of juvenile hormone can disrupt the normal development process of insects and make insects appear various metamorphosis types and die. Juvenile hormone has outstanding control effect on pea aphid, strawberry aphid and tobacco budworm. The use of sex pheromone can confuse insects, so that they can not find a mate and lose the chance of mating, and can not reproduce smoothly; or it is used to attract pests and kill them.

3.4 Sterile insectThe insects are treated with radiation or chemical agents, or radiation-sterile, chemical-sterile and genetic-sterile insects are bred by hybridization. Afterwards, the sterile individuals are released in large numbers to mate with natural insects in the field, making their offspring sterile. After generations of release, harmful insect populations are eliminated eventually.

3.5 Gene engineeringUsing gene transfer techniques, the disease-resistant and insect-resistant genes in other plants can be transferred to target crops, so that they will gain resistance to certain diseases and pests. In addition, pathogenic genes can be transferred to pathogens or pests to make them susceptible to diseases and die. For example, the use of a genetic material in the body of some bacteria can makeSpodopteralituraproduce lethal toxin.

4 Physical control

4.1 Trapping and killing pestsThere are many good instruments and tools for the prevention and control of pets, and the use of these instruments or facilities can directly kill pests or attract for centralized execution of pests, so as to control the number of pests. For example, all kinds of wire hooks used to kill longicorn, all kinds of carding tools, pull nets and sticky nets, black light lamps, metal halide lure lamps, high-voltage net pest control lamps combined with photoelectricity, aphid lure color plate, aphid-avoiding membrane, as well as crop stalks such as sorghum and corn used to lure pests to spawn or overwinter.

4.2 Protection of cultivation facilitiesSolar greenhouse, plastic greenhouse and other cultivation facilities are more and more widely used. After mulching with thin film, rain shelter cultivation can be realized and the occurrence of diseases can be reduced. The use of insect net on greenhouse and plastic greenhouse can play a role of physical barrier, and prevent the spread and harms of pests.

4.3 Heat treatmentSome pathogens can be killed by heat treatment. The common methods of heat treatment include soaking seeds in warm soup and treating seeds with hot water, to kill the pathogens carried by seeds. In summer, the implementation of high temperature tightly greenhouse for more than 10 d can effectively kill all kinds of diseases and pests in the shed and soil.

4.4 Application of light and raysSeed drying and soil drying is a method of using light rays to kill pathogens and pests in seeds and soil. Trapping pests with black light is also a way using light for pest control. With the continuous development of science and technology, a variety of high-energy rays, lasers and ultrasound are more and more widely used in the prevention and control of diseases and pests.

5 Chemical control

Chemical control has the advantages of quick effect, good effect, little influence by environmental conditions, easy for mechanized operation and so on, but it is easy to cause environmental pollution and excessive pesticide residues in products. As long as the problem of pesticide residues and drug resistance of control objects is solved, chemical control will still play an important role in the control of diseases and pests. Chemical control should pay attention to the following aspects.

5.1 Scientific selection of pesticidesEach pesticide has a suitable control object and a certain residue period. When using, we should carefully understand the nature of each pesticide, and make correct selection from the requirements of pollution-free and green product production, to achieve the purpose of controlling diseases and pests, protecting natural enemies and protecting the environment. At the same time, the type of pesticides for a control object should be changed frequently to reduce the resistance of pathogens and pests.

5.2 Correct mixture of pesticidesBecause of the different physical and chemical properties of various pesticides, some pesticides can not be used together, while some pesticides can be used together to improve the efficacy and save labor. In addition to the consistency of acid and alkaline, the pesticides with long-term and short effect, or contact and systemic effect can be mixed, and pesticide and fertilizer, pesticide and speader can be applied coordinatively.

5.3 Scientific application of pesticidesAccording to the nature of pesticides, climate conditions and the dynamics of the objects of control and protection, the concentration, frequency, dosage and application method of the pesticide are determined. For example, spray should be conducted on a fine, windless day, and must avoid the midday with high temperature.