Text|Famous City Rain
Editor|Mingchengyu
Pepper is an important vegetable crop in Egypt and worldwide. It is commonly attacked and destroyed by many plant parasitic nematodes, especially the root-knot nematode in Egypt. A better understanding of BCA biology and ecology makes them suitable for existing or emerging integrated pest management strategies for pepper cultivation. Examples of commercially produced biocontrol agents are presented.
Pepper PPNs in Egypt
Out of sight, beyond light, and therefore beyond much consideration, soil-transmitted nematodes often play a role in seeking the cause of yield losses in crops such as pepper. This general statement applies to PPNs, especially in developing countries. PPNs are microscopic roundworms that feed on plant roots, and their geographical distribution is highly dependent on temperature, soil type and cultivation history.
In pepper-growing areas, these nematodes live in soil and plant tissues, and several species of nematodes may appear in the field. The host ranges of these species vary. Symptoms of nematode infection also vary depending on the nematode species and crop type, but are usually non-specific. However, a small number of nematodes, especially root-knot nematodes, cause typical symptoms in the roots of infected plants.
Root-knot nematodes
These are obligate endoparasites of crop roots. One of the important factors that increase the importance of RKN is its wide range of hosts. The second stage juveniles hatch from the eggs and are worm-like. Supported by soil moisture, they move within the soil and into the roots of susceptible pepper plants.
Once inside the roots, they stop moving and modify the pepper root cells, while the host roots normally respond to infection, forming galls. Although the presence of galls indicates root-knot nematode infection, the size and shape of galls vary in different crops. The galls on pepper roots are usually not as pronounced and large as some other vegetable crops like tomatoes.
However, infected pepper root systems may contain millions of RKN eggs. Within these galls, nematodes develop into adult females. Each female can produce hundreds of eggs, which are contained in a gelatinous matrix. These eggs are usually deposited on the outside of the root, where J2 can appear to repeat the life cycle.
The latter is mainly determined by soil temperature. In warm conditions, the life cycle can be completed in less than 4 weeks. Thus, in one planting season, several life cycles can be completed. In other words, when conditions are favorable, low nematode population densities at the time of cultivation can quickly increase to high populations.
On newly reclaimed land in Egypt, as in some pepper-growing areas in California, relatively warm soil temperatures combined with predominantly light soil types, abundant soil moisture, and frequent planting of high-quality RKN host crops provide RKN with an ideal option to increase destructive population density.
Stunted plants with symptoms of decline usually occur in patches of uneven growth rather than uniform damage of peppers in the field area Unless appropriate RKN control measures are taken, infected fields of nematode pests have only a few such mottled areas at the beginning of the season, which may then increase the size of the infected area until the entire area where pepper is grown is almost infected.
Pepper plants infected with RKN are generally more susceptible to weed erosion than pepper plants that are not infected with nematodes. When plants are severely infected by RKNs, the normal root system is reduced to a limited number of severely RKN worn roots, with a completely disordered vascular system.
In addition, infected pepper plants are more vulnerable to drought damage. In severe infestations that can lead to plant death, small roots are almost completely absent. Ultimately, plant damage and yield loss depend on nematode population levels, host suitability, production practices, and biological and environmental conditions.
Pepper yield losses are often related to preplant disturbance density in soil and/or previous crop roots. This loss increases with the level of infection. If any Meloidogyne spp individuals are found every 100 cm, RKN control is required to control 3 soil for pepper cultivation in Egypt and other countries. This pre-planting threshold must not be used to grow plants.
Egypt should implement quarantine actions that successfully protect other plant species from nematode pests. All stakeholders in Egypt should work together to address this issue, in particular by allocating sufficient funds to produce enough certified seedlings of economically important plant species and training relevant experts who can carefully apply quarantine regulations.
Pre-planting sampling of nematodes is the basis of quarantine programs carried out mainly in pepper nurseries. These plans should focus on the selection of nursery locations to avoid runoff from infected fields and phytosanitary measures to prevent contamination of planting materials and equipment in nurseries and non-infected areas. Therefore, it is necessary to use the tools and equipment of the wireless bug.
Otherwise, such instruments must always be dewormed before being used in pepper nurseries and non-infected fields. Unfortunately, many growers are forced to obtain uncertified pepper seedlings from informal nurseries in private markets, as certified seedlings are relatively expensive and not readily available in Egypt.
The distribution restrictions of certified seedlings are further exacerbated by the lack of awareness of capsicum nematodes among many resource-poor growers. Egypt's quarantine of certifiable pathogens should also include bacteria, fungi and other transmissible pathogens.
In the European and Mediterranean regions, soil sun exposure, vegetable grafting and resistant cultivars are appropriate alternatives to the use of hazardous chemicals for the control of soil-borne plant pathogens. They found that "graffiti" was the most promising rootstock because of its resistance to Phytophthora capsicum and its tolerance to unknown mycobacteria.
In addition, one of the most effective, economical, and environmentally friendly ways to reduce pepper yield losses caused by nematode diseases is to use pathogen-resistant varieties. In addition, they noted that different nematode inoculation levels also failed to affect the yield of susceptible varieties "Crusaders" that exhibited tolerance; Its yield is not affected by RKN infection.
When the resistant "Carolina Miracle" and susceptible "Baron" pepper varieties were planted in soils with high levels of RKN infestation, the yield of resistant pepper was about 40% higher than that of susceptible varieties. Therefore, Ploeg and Aguiar say that the use of nematode-resistant varieties looks promising because it leaves lower nematode infestation levels and higher pepper yields at high initial nematode stress.
However, the suitability of these pepper varieties under commercial cultivation practices remains to be tested. In general, bell peppers appear to be more resistant to root-knot nematodes than some other vegetable crops, but the relationship between pre-plant RKN levels in soil and growth, yield, and harvest nematode levels should further identify Egyptian pepper varieties.
Although the above two pepper varieties are resistant, resistance expression is sensitive to heat. Therefore, the usefulness of these varieties at the highest soil temperature in Egypt needs to be characterized. Like tomatoes, the use of these varieties may have to be limited to winter and spring planting with low soil temperatures. Therefore, it is difficult to predict crop damage risk and decide on nematode management strategies based on the results of pre-planting samples.
In view of the above multiple views that the use of eco-friendly control methods to control pepper PPNs, the core of this paper is to focus on the application of PPNs, including various factors and mechanisms affecting PPN problems, optimize their biological control strategies, and pay attention to the new trend of integrated management of Egyptian nematodes. For such an INM, two types of sampling should be considered in advance.
Appropriate PPN sampling methods, timing, and procedures are necessary to detect and diagnose nematode problems through proper collection of relevant soil and plant tissues. These samples must be sent to nematode laboratories, such as the Diagnostic Service of the Special Department of the Dokki National Research Centre in Giza Province, for analysis prior to pepper transplantation.
The number of nematodes identified in these samples prior to seeding in nurseries and fields and the level of their species/genera determine whether nematode control is required. Another type of reasonable sampling should be used to maximize the separation of branched-chain amino acids. The overall goal of this functional sampling is to isolate, identify, and deploy highly effective strains against nematode pests before developing them into registered, ready-to-use plant protection products.
Foreign BCA products are available, but local products may be more adaptable and cheaper without posing significant risks to Egyptian flora and fauna. Indigenous BCAAs often exhibit relatively high efficacy, supporting the need for the development of piperine PPNs. Further serious attempts should be made to improve its efficacy.
It is important to apply this strategy, etc., because BCAs are generally slower, less effective, and more inconsistent than the controls normally achieved with chemicals. Therefore, different BCAA groups were reviewed to identify conditions and practices affecting their use for nematode management, as well as alternatives to maximize their useful applications to PPN.
To minimize costs, promote availability, optimize applications, and increase the efficacy of these BCAAs, this different method should be considered to manage pepper's PPN. For example, biopesticide producers can act simultaneously with distributors.
Such biocontrol strategies and strategies are particularly important because there are many biopesticides that are being or may soon be widely used. They examined fungal and bacterial nematicides, their mechanisms of action and other relevant information that influences the success of biological control programs against PPN and can provide a bright spot for their use against piperine nematodes.
The official biopesticide recommended by the Egyptian Ministry of Agriculture is avermectin. It is produced by living organisms during the fermentation of the actinomycete Streptomyces. The active ingredient is avermectin. Its unique chelating formula ensures effective protection of the active ingredient, bringing it into direct contact with PPN and obtaining optimal soil permeability.
Iron chelate provide the micronutrient iron that enhances soil fertility and health by increasing cation exchange capacity, increasing chlorophyll content, and promoting root quality. Its mechanism of action is concretized by blocking the transmission of electrical activity in invertebrate nerve and muscle cells, mainly by enhancing the role of glutamate in invertebrate-specific glutamate-gated chloride channels.
In soil, avermectin works mainly through contact activity. Fortunately, some new BCA products that have undergone PPN control testing are also able to compete with chemical nematicides in price. Some of them are even cheaper, which may expand their use to larger areas.
The labeling of these biopesticides can provide equipment and guidance to help stakeholders and growers store, prepare and apply these recently marketed biocontrol agents. The optimal storage temperature, the rate required for application in the specified area, the dosage or active ingredient, and the optimal application time are usually mentioned.
Researchers should further grasp the complex network of interactions between biological and abiotic factors in close contact with these branched-chain amino acids on pepper plants to maximize their benefits. To facilitate biocontrol of capsicum nematodes, the application of BCA products needs to be adapted to existing or emerging IPM strategies.
Therefore, opportunities to promote its integration into pepper management systems, application methods or take advantage of synergies/additive effects between BCA and other pest management strategies should be seized. In this spirit, chemical nematicides can be replaced to some extent by biological nematicides to reduce environmental impact.
As the use of broad-spectrum chemical nematicides decreases due to regulatory concerns and advances in BCA production and application, it is expected that the importance of BCA as an integral part of sustainable PPN management systems for pepper plants will develop into a more prominent role.
conclusion
Pepper is an important vegetable crop in Egypt, but its crop yield can be severely damaged by PPN. While chemical nematicides are effective in controlling nematodes, overuse can pollute the environment and cause health hazards. Therefore, the prevention of PPN introduction into newly reclaimed areas should be promoted through the development of relevant regulations and certification of seedlings.
Sound agricultural practices should be employed, but the prominent role of biological control agents in sustainable agriculture ranks high among other PPN management options. Therefore, different BCAA groups, especially those that have been shown to help reduce PPN populations and increase pepper growth parameters and/or yields, should be incorporated into pepper management systems.
Clearly, different aspects of BCA biology and ecology should be better grasped in order to adapt them to existing or emerging integrated pest management strategies for pepper cultivation.
bibliography
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