INTEGRATED MANAGEMENT OF TOMATO BURNING WITH FUNGICIDES AND ALTERNATIVE PRODUCTS: EFFECTS ON PRODUCTION
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WANDERSON BUCKER MORAES*, KARIN TESCH KULKAMP, WILLIAN BUCKER MORAES, LEÔNIDAS LEONI BELAN, GLAUCIO LUCIANO ARAUJO, SARA MORRA COSER, WALDIR CINTRA DE JESUS ​​JUNIOR**
Department of Plant Production, Center for Agricultural Sciences, Federal University of Espírito Santo, 29500-000, Alegre – ES, e-mail: wandersonbucker@yahoo.com.br*, wcintra@yahoo.com**
ABSTRACT:
This work aimed to evaluate the effect of the application of fungicides, micronomix and potassium silicate on tomato production. The experiment was carried out in a randomized block design with six treatments and three replications. The treatments (T) were: T1 – control; T2 – micronomix; T3 – protective fungicide (FP), alternating weekly with systemic fungicide (FS); T4 – potassium silicate, alternated weekly with micronomix; T5 – FP, micronomix and FS, alternated weekly; T6 – FP, micronomix+potassium silicate and FS, alternated weekly. The variables evaluated were: production, number of fruits and increase in production. There was an effect of the application of fungicides and alternative products on tomato production. Weekly applications of fungicides provided the highest production values. Plants from treatments 2 and 4 did not show significant increases in production. Treatment 6 proved to be promising, as it increased tomato production and reduced the number of fungicide applications.
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INTRODUCTION
Brazil is currently among the ten largest producers of tomato (Solanum lycopersicum) in the world (FAO-FAOSTAT, 2009). The tomato crop occupies the second place in order of economic importance among the oilseed crops in Brazil (SILVA et al., 2007). The importance of this culture can be attributed to its multiple forms of consumption, which can be used "in natura" or as industrial extracts. However, tomato production in Brazil is limited by several factors, with diseases being one of the main problems. Tomato cultivation is subject to attack by numerous pathogens, among which late blight (Phytophthora infestans) stands out. This disease is considered the most destructive of the crop, and can compromise the entire production field in a few days (VALE et al., 2000). Late blight occurs in practically all places where tomato is grown, being more severe in cold and humid periods. This disease can occur at any stage of the crop's development, severely affecting leaves, stems, fruits and petioles that, in general, present an aspect similar to burning or frost injury (JONES et al., 1993). The use of pesticides is one of the main ways of managing late blight, mainly due to the absence of varieties
resistant commercials, making control measures based on systematic applications of fungicides following a fixed weekly application schedule. These systematic applications of fungicides end up increasing the production cost, residue concentrations in the fruits to be marketed, in addition to endangering the life of the applicator, the neighboring population and other living beings of the ecosystem in question (JESUS ​​JUNIOR et al., 2007; VALE et al., 2007). Aiming to rationalize the use of fungicides in the management of late blight and to make the tomato crop more profitable, several measures have been studied. Among these measures, we highlight the use of alternative products with the potential to control phytopathogens or the alternation of these with fungicides, seeking synergism between fungicides and alternative products. Silicon (Si), although not essential to plants, is considered agronomically beneficial, being pointed out as an alternative in the management of numerous diseases in different crops such as rice, cucurbits, soybeans and wheat (DATNOFF et al., 2007). The mechanism of resistance to diseases conferred by Si is due to the formation of physical barriers by its deposition below the cuticle or this element may be associated with the potentiation of several defense mechanisms such as the production of phenolic compounds, phytoalexins and activation of some genes that encode proteins
related to pathogenesis (RODRIGUES et al., 2003, 2004, 2005). Among the sources of silicon, liquid and soluble potassium silicate (K2SiO3) is one of the most used sources for the supply of Si via foliar applications in plants (ZENÃO JUNIOR et al., 2009). Another alternative product that has the potential to be used in disease management is organomineral fertilizer, whose trade name is micronomix®. This acts by providing a rapid assimilation of available nutrients, increasing the production of plant mass, a fact that can make the plant resistant to pathogens (TECNOBIOL, 2005). This study evaluated the effect of the application of fungicides, micronomix and potassium silicate on tomato production.
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CONDUCTING THE EXPERIMENT
The experiment was carried out in the experimental area of ​​the Agricultural Sciences Center of the Federal University of Espírito Santo, in Alegre – ES (altitude 150m, latitude 20º 45′ S and longitude 41º 28′ W), from April to July 2007. The experimental design was randomized blocks with six treatments and three replications. Each plot consisted of 40 plants divided into four rows, with two lateral rows left as borders. Within the central rows, three plants from the end of each row were left as borders, resulting in 8 useful plants in the central part of the plot. The tomato cultivar used was Santa Clara, which is susceptible to late blight. The seedlings were transplanted to the field at 25 days after sowing, when the plants presented five pairs of definitive leaves using spacing of 0.60m between plants and 1.2m between rows. The cultural treatments were carried out according to the recommendations for the culture, performing the correction of soil acidity, fertilization and pest control according to the technical indications (CAMARGO, 1981; FILGUEIRA, 2003). The treatments (T) consisted of the application of fungicides (systemic and protective), micronomix and potassium silicate, isolated, alternated and/or associated. The following treatments were used with the respective doses in grams of active ingredient per hectare (g i.a.ha-1): T1 – control; T2 – application of micronomix (1.25 mL.L-1); T3 – application of protective fungicide (mancozeb, 1600 g a.i.ha-1), alternating weekly with systemic fungicide (cymoxanil + mancozeb, 160 + 1280 g a.i.ha-1); T4 – application of potassium silicate (40 g.L-1), alternating weekly with . micronomix; T5 – protective fungicide, micronomix and systemic fungicide, alternated weekly; T6 – protective fungicide, micronomix+potassium silicate (associated) and systemic fungicide, alternated weekly. The spraying of treatments on the aerial part of the plants was carried out weekly, starting after the appearance of the first symptoms of the disease. To apply the treatments, a 20-liter manual backpack sprayer with a conical nozzle was used, calibrated for the application of a spray volume of 1000 L.ha-1.
QUANTIFICATION OF TOMATO PRODUCTION
The harvests were made when the fruits reached the ripe green stage or pale green coloration (MAKISHIMA et al., 1980), being carried out weekly. Commercial fruits were counted and weighed per plant in each useful plot. From the weekly data, the sum of the fruit production per plant (Kg.plant-1) and the number of fruits per plant was performed. To evaluate the effect of fungicides and alternative products on the increase in production, the increase in production was calculated.
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RESULTS
Applications of fungicides and alternative products influenced tomato production (Figure 1). It was found that weekly application of micronomix did not increase tomato production (P ≤ 0.05, Figure 1). The lowest values of production, number of fruits and increase in production were observed in plants of treatments 1, 2 and 4. Plants treated with weekly applications of fungicides showed the highest values of production, number of fruits and increase in production (P ≤ 0 .05, Figure 1).
Treatment 5 (alternating fungicides with micronomix) provided intermediate values of production and increased production (P ≤ 0.05, Figure 1).
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FIGURE 1 – Production (Kg.plant-1) (A), Increase in production (B) and Number of fruits per plant (C) for the different treatments. Means followed by the same letter do not differ from each other by the Scott-Knott test, at the 5% probability level. Treatments: T1 – control; T2 – micronomix; T3 – protective fungicide (FP), alternating weekly with systemic fungicide (FS); T4 – potassium silicate (40 g.L-1), alternated weekly with micronomix; T5 – FP, micronomix and FS, alternated weekly; T6 – FP, micronomix+potassium silicate and FS, alternated weekly.
Plants in treatment 6 (alternating fungicides with micronomix+potassium silicate) showed higher production values, number of fruits and production increment than those obtained in treatments 1, 2, 4 and 5 (P ≤ 0.05, Figure 1).
DISCUSSION
With the advent of anti-oomycete fungicides, significant progress has been made in controlling late blight. The positive results obtained in this study for the production of tomato plants treated with the fungicide cymoxanil+mancozeb and mancozeb corroborate this statement. Some research works have highlighted the effectiveness of controlling some fungicides such as metalaxyl-M and its mixtures with mancozeb and chlorothalonil, cymoxanil + maneb + ​​zinc sulfate, dimetomorph, famoxadone + cymoxanil, propamocarb+chlorothalonil and mancozeb, among others (TÖFOLI & OLIVEIRA , 1998, TÖFOLI et al., 2000, 2003). Töfoli et al. (2003) verified that the management of tomato late blight with cymoxanil+mancozeb and fluazinam provided better results than those obtained with chlorothalonil. Weekly applications of micronomix alone or alternated with potassium silicate and fungicides were not efficient in promoting an increase in tomato production. Such results are due to the inefficiency of these treatments in the management of late blight in tomato. Studies on the use of alternative products in the management of late blight have been carried out, aiming to reduce the use of agrochemicals. There are few reports in the literature on the effect of micronomix on plant disease management. Some reports describe positive effects of this compound in the control of pests and diseases in other crops. PRATISSOLI et al. (2007) verified a reduction in the incidence and severity of smallpox in the papaya crop. ALMEIDA et al. (2008) observed negative effects of micronomix on whitefly population in bean crop. Duarte et al. (2008) verified that the treatments constituted by the mixture of cymoxanil+mancozeb (2.5 Kg.ha-1 and 3.0 Kg.ha-1) and potassium silicate and application of cymoxanil+mancozeb (2.5 Kg. ha-1 and 3.0 Kg.ha-1) were the most efficient treatments to control late blight in potato. However, the use of isolated potassium silicate has been shown not to be efficient in the management of late blight in tomato. Duarte et al. (2007) observed that applications of potassium silicate at doses of 5 and 15g.L-1 were not efficient in reducing the progress of late blight in tomato and increasing the production of this crop. The results obtained in plants that received treatment 6 (fungicides alternated weekly with micronomix+potassium silicate) proved to be promising. Plants that received this treatment showed an increase in production, even with a 50% reduction in the number of fungicide applications. Pratissoli et al. (2007) found greater reductions in papaya smallpox intensity with the application of micronomix associated with silicate clay. In the management of the disease in alternative production systems, it is necessary to integrate practices to potentiate the individualized effects (DINIZ et al.; 2006). Currently, the use of fungicides to control late blight has been recommended within multidisciplinary management programs. In these, the knowledge of the control potential of each product, including alternative products and their combinations, is a fundamental requirement for them to provide the best results in application programs. It is worth mentioning that in this study a moderate application schedule was used, respecting the application interval. However, due to the enormous potential for damage caused by tomato late blight, producers come to carry out daily applications in conventional cropping systems, when environmental conditions are favorable for the development of this pathogen. Therefore, the management system used by some producers does not respect the grace period of the products, thus leaving residues in the fruits. Thus, treatment 6 was efficient in the management of late blight of tomato, as it promoted an increase in tomato production and a reduction in the number of applications performed during the crop cycle. Therefore, the use of this treatment in the management of this disease can provide a considerable reduction in the number of applications with fungicides in conventional tomato cultivation, thus reducing residue concentrations in the fruits to be commercialized.
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CONCLUSION
There was an effect of the application of fungicides and alternative products on tomato production. Weekly applications of fungicides provided the highest values ​​of production, increment and number of fruits. The use of micronomix alone or alternated with potassium silicate does not increase tomato production. The use of fungicides alternated weekly with micronomix+potassium silicate increased tomato production and reduced the number of fungicide applications.
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