The tomato plant (Solanum lycopersicum L.) is a plant species belonging to the solanaceae family. Originally from Andean countries in South America, it is cultivated worldwide to meet the population's high demand for fresh fruit consumption, as well as processed for sauces and ketchups. An estimated global area of 4,7 million hectares with annual global production of 159 million tons, with China, India, the USA and the Mediterranean Coast being the main producers. Brazil ranks 9th among the main producing countries in the world, with an annual cultivated area of approximately 65 thousand hectares with production of 4,3 million tons.
It is an intensive cultivation that requires high technology and inputs of agricultural inputs and which results in high productivity. In Brazil, the majority of production comes from cultivation in open-air fields, but cultivation in a protected environment has increased over time to guarantee the production of tomatoes in places and seasons that are adverse to cultivation, which allows for supply in the off-season. The largest producing states are Goiás, São Paulo, Minas Gerais and Bahia, but the crop has economic relevance in most Brazilian states.
For processing, tomato plants with a determined habit are used, with low growth and generally cultivated in larger areas in an extensive manner. For consumption in natura, the tomato plant with an indeterminate habit conducted by vertical staking is the most cultivated, although some producers opt for the cultivation of tomato plants with a determinate growth (creeping) to produce fruits for fresh consumption. However, the pests and diseases that attack the crop for both processing and fresh are practically the same, regardless of the cultivation method.
The pathogens that attack tomato plants range from fungi, bacteria and soil nematodes that penetrate the plant through the roots, to aerial part diseases, fungi and bacteria that attack leaves and fruits.
Among the most problematic are soil fungi of the genus Fusarium, mainly Fusarium oxysporum races 1, 2 and 3, and gender Verticillium and the bacteria Ralstonia solanacearum, pathogens that cause wilting problems in the aerial part of tomato plants by attacking the plant's vascular system. However, it is through dealing with the soil that the entire process of integrated biological control of tomato pests and diseases begins. A soil with high biological dynamics and chemical and physical balance is the driving force for the success of healthy and productive cultivation. Understanding that the soil is actually a living organism and that it responds greatly to treatments that favor the organisms present in it is the main starting point for successful production based on biological control.
In this context, crop rotation with cover crops such as sunn hemp, mucunas, millet, oats and lupins is an extremely desired principle to increase the biological activity of the soil and suppress the action of unwanted pathogenic organisms, a fact provided by the increase in organic matter and activity. exudation of biomolecules by the root system, which provides strong rhizospheric interaction with soil microorganisms. A Crotalaria spectabilis, for example, is highly efficient in reducing the population of nematodes in the soil by trapping the female in the roots and consequently reducing proliferation. Grasses such as oats and millet suppress the action of Fusarium. Lupine solubilizes phosphorus adsorbed in soil colloids for microorganisms and plants, a fact that increases biological activity. Thus, for each specific case there are possibilities for cover crops to rotate with the tomato plant and thus achieve desired agronomic results by stimulating the biological activity of the soil and reducing agricultural inputs. Biologically fertile soil is synonymous with healthy plants and terrestrial life.
The application of biotechnology in agriculture is increasingly evident nowadays. As an example of great efficiency in biological control in the case of nematodes, which is a serious problem in tomato cultivation, there are fungi Trichoderma harzianum, Paecilomyces lilacinus that parasitize eggs and females. These fungi have enormous potential for controlling nematodes and pathogenic fungi through the action of competition, antibiosis, parasitism and induction of plant resistance, which classifies them as having a high degree of biological control efficiency. These fungi must be applied to the seedlings before transplanting and then sprinkled on the soil or injected into the irrigation water to reach the target. It is noteworthy that the conservation of straw in the soil is desired to increase the degree of efficiency of control action of these biological agents.
Bacillus subtilis e Bacillus sp. are bacteria that induce systemic resistance to diseases in plants. For tomato cultivation, these bacteria have demonstrated suppression efficiency against Fusarium sp and Ralstonia solanacearum. Applications of these microorganisms to seedlings before transplanting are recommended and directed to the soil via spraying or injected into the irrigation water and also sprinkled on the leaves. There are indications that Bacillus subtilis has control action on foliar diseases such as early blight (Alternaria Solani) and bacterial stain (Xanthomonas campestris PV. vesicatoria).
Grafting with rootstock resistant to soil pathogens such as bacterial wilt (Ralstonia solanacerum) has high tolerance efficiency to these diseases. However, in areas contaminated by these pathogens, grafting is recommended as cultural management.
In the initial growth phase, up to approximately 45 days to 50 days after transplanting the seedlings, the tomato plant is very sensitive to viruses, mainly the virus and geminivirus, which are transmitted by insect vectors, in this case thrips (Fraklinilla shultzei) transmitter of the head turner and the whitefly (Bemisia tabaci) transmitter of the geminivirus. In the tomato seed market there are several hybrid options that have tolerance to these viruses, however there are always reports of incidence of these diseases in commercial crops and even in a high percentage, depending on the growing conditions. Some other “less important” viruses in tomato crops, such as Tomato Mosaic Virus and Tobacco Mosaic Virus, may also occur mainly in susceptible varieties. These viruses are transmitted by aphids, an insect that is controlled by the same biological treatment used to combat thrips.
However, controlling these insects is essential to avoid high-level plant infection in tomato cultivation. For the biological control of thrips, aphids and whiteflies, entomopathogenic fungi Metharizium anisopleae e beauveria bassiana have shown good performance in controlling these virus-transmitting insects. The recommendation for treatment is weekly application from transplanting until the end of the cultivation cycle, as these fungi will also have an effective action on pests that attack tomato plants in the middle and end of the cycle. A very important observation regarding the application of fungi is that applications should always be carried out in the late afternoon to avoid the action of ultraviolet rays, which are lethal to these organisms.
For whiteflies, a limolene-based product has good anti-control action by disintegrating the insect's protective chitinous protection and exposing the action of natural enemies and entomopathogenic fungi such as beauveria bassiana.
The cultural management of “roguing”, which is the eradication of infected plants, is significant in reducing the spread of the virus in tomato crops. “Roguing” should be carried out regularly, at least weekly, and increase the frequency whenever the incidence of viruses is high.
Tomato is a crop that suffers strong pressure from pathogens with foliar action. Among the main foliar fungal diseases present in Brazil are early blight (Alternaria Solani), late blight (Phytophthora infestans), septoria (Septoria lycopersici) and stenphilium spot (Stemphylium solani e S. lycopersici). Regarding bacterial foliar diseases, the most significant in Brazil are bacterial spot and bacterial blight. The supply of hybrids tolerant to these diseases is still low on the seed market.
In integrated management for these diseases, the principle of balanced nutrition of the plant is based on so that the crop is well prepared to strengthen its natural defense and immunity metabolism. Therefore, it is important that the chemical, physical and biological fertility of the soil is strengthened, so that the plants' immune system is prepared to face these biotic agents. Based on the basic principle of soil fertility, some biological treatments are recommended that will provide significant results in combating diseases. It is already public knowledge that the fungus Beauveria basiana It has endophytic and systemic action on plants and thus stimulates the plants' immune system against phytopathogens. Therefore, applications of this fungus throughout the tomato cultivation cycle, in addition to insect control, will help combat diseases caused by fungi and bacteria by naturally stimulating the plant's immune system.
Essential oils and plant extracts are elements with high potential for controlling tomato diseases, although they are not biological organisms, they are natural sources to be used as a method of natural control of tomato pests and diseases. Tea tree oil (Melaleuca alternifolia), for example, has strong potential in combating foliar fungi and bacteria, and there is already a product available on the national market registered for tomato cultivation. Lemongrass essential oils significantly reduce the incidence of early blight on tomato plants. Along these lines, essential oils and plant extracts are very promising in combating plant diseases and pests. Neem Oil (Azadirachta indicates A. Juss) extracted from the leaves and seeds of the plant is effective in controlling insects in general and can be used in tomato cultivation.
The complex of pests that attack tomato plants begins with pests inherent to the beginning of the cultivation cycle, which are the first 30 days after transplanting the seedlings. The main pests at this stage are thrips, aphids, whiteflies, which are virus-transmitting insects, and some soil caterpillars that can eventually cause damage to seedlings, reducing the plant stand. So, fungus treatment Metharrizium anisopleae e beauveria bassiana and the bacteria Bacillus thurigiensis are efficient in controlling it. Applications directed to the soil and plant are recommended.
Insects from the Lepdopteras family, moths with crepuscular and nocturnal habits, are important pests of tomato plants and attack vegetative and fruitful organs. The leaf-mining larva (Liriomyza huidobrensis) grows inside the leaves between the adaxial epidermis (upper surface) and abaxial epidermis (lower surface) forming galleries that destroy the leaf blade, causing loss of photosynthetic area and opening for pathogens to enter. The tomato moth (Tuta absoluta) destroys vegetative apical meristems, in addition to fruits in initial growth, causing direct damage to plant growth and destruction of fruits. The small tomato fruit borer (Neoleucinodes elegantalis) attacks the fruits internally through the action of insect larvae; Eggs are laid on the petals of flowers and fruits at the beginning of growth, days after the flower is fertilized. The eggs hatch and the larva penetrates the young fruit, feeding on the pulp during the growth of both caterpillar and fruit. The fruits grow and days before the harvest point the larvae leave them, causing holes that completely compromise the fruits, making them unviable for sale.
Fungus treatment Metharizium anisopleae e beauveria bassiana and the bacteria Bacillus thurigiensis, which had already been applied in the early stages of tomato cultivation, is the same recommended for controlling moths, especially after flowering, with the same frequency and dosage of application. Applications directed to the flowers, fruits and foliage of the plant are recommended always during the twilight period of the day.
The Trichogramma (Trichogramma pretiosum), parasitoid of moths, has a strong effect on controlling moths and small fruit borers. After flowering, the parasitoid begins to release so that the insect lays its eggs in moth eggs located on tomato leaves and fruits. Thus, when hatching, the eggs T. pretiosum inside moth eggs will lead to their destruction, interrupting the moth cycle, reducing the pest population. In this way, biological control of tomato pest caterpillars occurs with high efficiency. It is recommended to release it weekly, always at cooler times of the day.
Homeopathy, although not a biological agent for controlling pests and plant diseases, has been widely used in organic tomato cultivation, as it is a natural process, acting on energetic quantum principles and which has been quite successful when used correctly.
In fact, biological control with fungi and bacteria for tomato pests and diseases is a reality with a significant degree of efficiency, as long as environmental measures are taken into account, such as Conservationist Agriculture, which has as its principles minimum soil disturbance or direct planting, crop rotation and permanent maintenance of vegetation cover on the soil surface to conserve soil and water and preserve the property's native vegetation within current environmental laws. However, there is no miracle product to combat tomato pests and diseases, whether biological or chemical in nature. But the sum of factors of understanding the landscape and stimulating life in the agroecosystem will lead to successful organic tomato production. The use of any and all products must be preceded by technical recommendations, prepared by a professional in the field.
Roberto Botelho Ferraz Branco, Ag. Paulista de Tecn. of Agribusiness – Agronomic Institute (Apta - IAC – Horticulture Center)
With each new edition, Cultivar Hortaliças e Frutas publishes a series of technical content produced by renowned researchers from all over Brazil, which address the main difficulties and challenges encountered in the field by rural producers. Through research focused on controlling the main pests and diseases in vegetable and fruit cultivation, the Magazine helps farmers in the search for management solutions that increase their profitability.
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