Bioscience Journal | 2021 | vol. 37, e37052 | ISSN 1981-3163 1 Gislaine GABARDO1 , Maristella DALLA PRIA2 , Henrique Luis DA SILVA3 , Mônica Gabrielle HARMS1 1 Postgraduate Program in Agronomy, State University of Ponta Grossa, Ponta Grossa, PR, Brazil. 2 Department of Agronomy, State University of Ponta Grossa, Ponta Grossa, PR, Brazil. 3 Science and Technology Analyst, Rural Development Institute of Paraná, Ponta Grossa, PR, Brazil. Corresponding author: Gislaine Gabardo Email: gislainegabardo2007@yahoo.com.br How to cite: GABARDO, G., et al. Alternative products to control powdery mildew in soybeans culture in field. Bioscience Journal. 2021, 37, e37052. https://doi.org/10.14393/BJ-v37n0a2021-53681 Abstract The occurrence of powdery mildew (Microsphaera diffusa) in soybean (Glycine max L.) has increased in the last harvests. In order to study the efficiency of powdery mildew control due to the application of alternative products and conventional fungicide, trials were conducted in Ponta Grossa, PR, Brazil, during the 2013/2014 and 2014/2015 growing seasons. The design used was randomized blocks with four replications. The treatments for the experiments were: 1 - control; 2 - acibenzolar-S-methyl (Bion 500 WG®); 3 - calcium (Max Fruit®); 4 - Micronutrients: copper, manganese and zinc (Wert Plus®); 5 - Micronutrients: manganese, zinc and molybdenum (V6®); 6 - NK fertilizer (Hight Roots®); 7 - Ascophyllum nodosum (Acadian®) and 8 - fungicide (azoxystrobin + cyproconazole) (Priori XTRA®) with the addition of the adjuvant. Four applications of alternative products (phenological stages V3, V6, R1 and R5.1) and two of fungicide (phenological stages R1 and R5.1) were carried out. The parameters evaluated were powdery mildew severity and productivity. The severity data made it possible to calculate the area under the disease progress curve (AUDPG). Alternative products didn’t reduce powdery mildew in the two harvests. The conventional fungicide treatment was the only one that controlled powdery mildew and didn’t reduce the productivity in both experiments. Keywords: Acibenzolar-S-methyl. Fungicide. Glycine max L. Micronutrients. Microsphaera diffusa. 1. Introduction Soybean (Glycine max (L.) Merril) is the most important oilseed globally (Anderson et al. 2019). Due to its productive potential, protein source, chemical composition and nutritional value (USDA 2019). It is the main grain crop produced in Brazil, however the occurrence of diseases is a limiting factor for high yields (Battisti et al. 2018). Among the diseases, powdery mildew caused by the fungus Microsphaera diffusa Cke. & Pk. stands out, since the 1996/97 harvest it has gained importance among the diseases that affect soybeans in the South and Midwest regions of Brazil, causing damage to yield estimated between 30% and 40% (Blum et al. 2016; Roese et al. 2017). The significant reduction in soybean yield is due to the reduction of the photosynthetically active area (Barcelos et al. 2018). ALTERNATIVE PRODUCTS TO CONTROL POWDERY MILDEW IN SOYBEANS CULTURE IN FIELD https://orcid.org/0000-0003-0723-6297 https://orcid.org/0000-0002-7907-2773 https://orcid.org/0000-0002-0078-1666 https://orcid.org/0000-0003-4254-9993 Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 2 Alternative products to control powdery mildew in soybeans culture in field It is a mandatory parasite, which depends on the living host for its survival, growth and reproduction. The pathogen survival in tropical and subtropical regions occurs through mycelium and conidia produced by the fungus in plants of the host itself, in weeds or in voluntary plants (Godoy et al. 2016). There are resistant cultivars (Leite et al. 2016), however, there is great variation in the genotype’s reaction between locations for susceptibility to the fungus M. diffusa, due to the possibility of different physiological races among populations that occur in Brazil, then chemical control is the most used to control this disease (Pereira et al. 2012; De Almeida et al. 2017). The indiscriminate use of pesticides can cause the selection of fungicide resistant strains of fungi, cause damage to the environment, lead to environmental imbalance, in addition to impacting the cost of crop production (Arruda et al. 2012; Tupich et al. 2017) and Brazil being the largest consumer of pesticide products in the world (Friedrich et al. 2018). In this context, the productive processes adopted in agriculture have been under pressure from society to produce food in a sustainable manner and without residues (Sentelhas et al. 2015; Pinela et al. 2017), which has led researchers to seek alternative measures for disease control. In addition to evaluating products trigger plant defense mechanisms, providing a further control alternative (Gabardo et al. 2020). Thus, the present study aimed to evaluate the effect of foliar application of alternative products on the severity of powdery mildew in field and its influence on soybean crop productivity under no-tillage system in the cultivar BMX Potência RR in the 2013/2014 and 2014/2015 growing seasons. 2. Material and Methods Two experiments under field conditions were conducted in Ponta Grossa - PR, Brazil, located at 25°13'latitude and 50°03'longitude and 900 m altitude, in the 2013/2014 and 2014/2015 growing seasons. The soil at the site is classified as a typical Eutrophic INCEPTISOL soil, clay texture (EMBRAPA 2006). The cultivation system adopted in the area is direct planting with straw. Monthly average temperatures, monthly total precipitation, and average humidity of the experimental area in the period were collected daily in an automated agrometeorological station located close to the experimental field. The soybean cultivar used was BMX Potência RR, with sowing carried out under no-tillage system, on wheat straw, on 12/18/2013 and 12/16/2014, using 0.45 m spacing between rows with 15 seeds per meter to obtain density of 12 plants m-1 and final population of 250,000 plants ha-1. The experimental design adopted was randomized blocks, with 8 treatments and four replications, in plots measuring 6.0 x 4.0 m (24 m2), with a useful area of 5.0 x 1.8 m (9.0 m2). The treatments consisted of foliar application of the products: 1 - control (water); 2 - acibenzolar-S-methyl (Bion 500 WG®) (25 g c.p. ha-1); 3 - calcium (Max Fruit®) (0.75 L c.p. ha-1); 4 - micronutrients: copper, manganese and zinc (Wert Plus®) (0.75 L c.p. ha-1); 5 - micronutrients: manganese, zinc and molybdenum (V6®) (0.75 L c.p. ha-1); 6 - NK fertilizer (Hight Roots®) (0.75 L c.p. ha-1); 7 - extract of the seaweed Ascophyllum nodosum (Acadian®) (2.0 L c.p. ha-1) and 8 - azoxystrobin + cyproconazole (Priori XTRA®) (300 ml c.p. ha-1) and adjuvant (0.5% v/v ). The development of soybean culture was accompanied by the phenological scale proposed by Fehr and Caviness (1977), reviewed by Ritchie et al. (1997). In the two experiments, 4 applications of alternative products were carried out in the phenological stages V3 (second developed trefoil), V6 (fifth developed trefoil), R1 (beginning of flowering) and R5.1 (grains noticeable to the touch (10% of grain)) and two applications of fungicide in the phenological stages R1 and R5.1. The applications were carried out using a knapsack sprayer with constant pressure (CO2), equipped with a bar with simultaneous arrangement of four flat fan spray nozzles (XR 11002) spaced 0.50 m apart and pressure of 3 kg cm-². A flow rate of 250 L ha-1 was used for all treatments. Inoculation, basic fertilization and weed and pest control were carried out according to the needs of the crop. Assessments of powdery mildew severity were performed weekly during culture cycle from the first symptoms. The percentage of leaf tissue attacked in the leaves of 10 plants random chosen was estimated in two lines of the useful area of the experimental plot. Each plant was evaluated in its thirds (lower, middle, and upper) and the thirds average used for the entire plant grade. Nine evaluations were carried out in the 2013/2014 growing season and seven evaluations in the 2014/2015 growing season of the severity of powdery mildew. The severity of powdery mildew was estimated with the aid of Mattiazzi (2003) Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 3 GABARDO, G., et al. diagrammatic scale. These data made it possible to calculate the area under the disease progress curve (AUDPG) (Shaner and Finney 1977). To determine the productivity, all plants in the useful area of the experimental unit (9.0 m²) were cut and threshed with a Triton stationary beater. The volume of grains of each plot was weighed and its moisture was determined, being converted to 13% humidity, for the calculation of the final productivity (kg ha-1). The data obtained were subjected to analysis of variance by the F test and the significant means were grouped by the Scott-Knott test at 5% probability. The severity data in individual evaluations were transformed into arcsin√(x + 0.5)/100. The analyzes were performed with aid of the statistical software SASM-Agri (Canteri et al. 2001). 3. Results and Discussion Infection by the pathogen M. diffusa can occur at any stage of plant development, however, it is more visible at the beginning of flowering, the typical symptom of powdery mildew being a whitish to gray layer, consisting of mycelium and powdery conidia, which can cover the entire plant aerial part (Jun et al. 2012). In the experiment, the first symptoms of powdery mildew were observed in V6 (37 DAE), remaining in the rest of the cultivar cycle (Figure 1 and Table 1) in both the first and second harvest. According to Xavier et al. (2015) this is because pathogens in the group of mildew present a highly evolved form of parasitism, as they depend on the living host for their survival, growth and reproduction, and can coexist throughout the life cycle with the plant. Figure 1. Severity (%) of powdery mildew (Microsphaera diffusa) obtained in the control in the 2013/2014 and 2014/2015 growing seasons, depending on the days after the emergence of soybean (Glycine max L.), cultivar BMX Potência RR. Ponta Grossa, PR. The importance of each disease varies from year to year and from region to region depending on the climatic conditions of each growing season. Environmental conditions are fundamental in the development of powdery epidemics, with periods of drought, temperature between 20 and 25°C and relative humidity between 50 and 90%, favor the development of disease epidemics (Godoy et al. 2016). There was a difference between the severities in the two growing seasons (Figure 1), this difference can be explained due to climatic conditions. In the first experiment (2013/2014 growing season) powdery mildew developed slowly from February. This can be explained by the average temperature of 19.5°C, relative humidity 87.4%. In the 2014/2015 growing season, powdery mildew developed rapidly in February, which can be explained by the average temperature of 20.7°C, relative humidity of 85.4%. Late sowing (December) favored the occurrence of the disease, culminating in a maximum severity of 71.35% at 100 DAE in the first growing season, and in the second growing season a maximum severity of 73.50% at 80 DAE. The fungicide application showed a maximum control of 85.45% and 76.03%, in the first and second growing season respectively (Figure 1 and Table 1). Silva et al. (2013) found control of powdery mildew in soybeans up to 90% using two applications of the fungicide pyraclostrobin + epoxiconazole, a mixture of strubirulin and triazole, similar to the product 0 10 20 30 40 50 60 70 80 35 40 45 50 55 60 65 70 75 80 85 90 95 100105 S e v e ri ty ( % ) Days after emergence Season 2013/2014 Season 2014/2015 Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 4 Alternative products to control powdery mildew in soybeans culture in field tested in the present experiment, in which the maximum control was lower (85.45% and 78.91%) indicating a possible loss of product efficiency. In the present experiment, leaf fertilizers had no effect on powdery mildew (Table 1). However, Marschner and Marschner (2012) state that the nutritional status in which plants are found is directly related to the responses expressed by them. Nutritional imbalance, whether due to excess or lack of certain nutrients, favors the establishment of diseases and/or pests according to the nutrient(s) in imbalance in the plant tissue. Thus, due to their effect on growth pattern, morphology and anatomy, and particularly on the chemical composition of the plant, mineral nutrients can increase or decrease plant resistance to pests and diseases (Altieri and Nicholls, 2003; Macoski et al. 2021). In the case of fungal diseases on the surfaces of roots and leaves, protection through balanced mineral nutrition would be the result: the formation of an efficient physical barrier, preventing the penetration of hyphae, through thick cuticle, lignification and/or accumulation of silicon in the layer of epidermal cells; better control of cytoplasmic membrane permeability, thus preventing the outflow of sugars and amino acids (on which pathogens feed) into the apoplast, or intercellular space; formation of phenolic compounds, with distinct fungistatic properties, in addition to biochemical mechanisms for inducing plant resistance against pathogens and pests (Shittu et al. 2021). Table 1. Severity (%) of powdery mildew (Microsphaera diffusa) at 37 DAE (V6), 44 DAE (R1), 51 DAE (R2), 64 DAE (R5.1), 72 DAE (R5.2), 80 DAE (R5. 3), 85 DAE (R5.4), 95 DAE (R5.5) and 100 DAE (R6) in the 2013/2014 growing season and at 37 DAE (V7), 41 DAE (V8), 53 DAE (R2) 59 DAE (R3), 66 DAE (R5.1), 73 DAE (R5.2), 80 DAE (R5.3), in the 2014/2015 growing season, in different treatments performed with alternative products and fungicide on soybean (Glycine max L.), cultivar BMX Potência RR, average of the whole plant. Ponta Grossa, PR. Treatment 2013/2014 growing season Severity of powdery mildew (%) 37 DAE 44 DAE 51 DAE 64 DAE 72 DAE 80 DAE 85 DAE 95 DAE 100 DAE 1- Witness (water) 0.08ns* 2.19ns 12.48ns 22.46a 26.31a 30.22a 38.21a 55.40a 65.09a 2- Acibenzolar-S-methyl 0.06 1.83 9.03 18.77a 21.91a 24.82a 34.47a 46.94a 64.32a 3- Macronutrients: Ca 0.07 1.95 9.88 20.22a 27.23a 31.01a 37.89a 53.52a 69.93a 4- Micronutrients: Cu; Mn; Zn 0.08 0.96 8.49 18.11a 29.03a 24.59a 34.74a 50.98a 61.90a 5- Micronutrients: Mn; Zn; Mo 0.07 1.45 7.96 19.86a 24.36a 28.19a 35.32a 48.20a 62.65a 6- NK fertilizer 0.06 1.38 7.92 18.32a 26.92a 28.90a 35.73a 51.51a 64.95a 7- Ascophyllum nodosum 0.08 1.58 6.88 20.67a 24.73a 30.73a 36.74a 52.52a 71.35a 8- azoxystrobin + cyproconazole 0.08 1.06 7.96 12.44b 12.83b 5.64b 5.56b 13.79b 22.31b C.V. (%) 38.90 33.53 25.83 15.44 13.99 14.34 11.15 10.95 10.86 Treatment 2014/2015 growing season Severity of powdery mildew (%) 37 DAE 41 DAE 53 DAE 59 DAE 66 DAE 73 DAE 80 DAE 1- Witness (water) 5.90ns* 8.13ns 22.68ns 30.21a 40.58a 47.29a 70.54a 2- Acibenzolar-S-methyl 6.95 7.99 18.31 24.53a 34.45a 45.24a 73.50a 3- Macronutrients: Ca 5.45 7.50 24.28 24.82a 37.58a 45.85a 67.62a 4- Micronutrients: Cu; Mn; Zn 6.82 8.03 22.15 23.56a 38.27a 41.82a 66.71a 5- Micronutrients: Mn; Zn; Mo 6.01 7.62 23.43 23.09a 34.61a 44.25a 69.43a 6- NK fertilizer 6.42 6.07 23.15 24.46a 38.02a 45.68a 68.20a 7- Ascophyllum nodosum 5.72 7.74 24.34 29.45a 37.39a 43.45a 66.96a 8- azoxystrobin + cyproconazole 5.82 5.56 14.85 11.34b 8.56b 13.33b 17.62b C.V. (%) 21.97 22.95 20.97 18.77 14.32 13.88 9.25 *Averages followed by the same lower case letter in the column do not differ by the Scott-Knott test at 5% significance; Original data, for analysis, the data were transformed into arc sen √ ((x + 0.5)) / 100 ns = not significant; DAE = days after emergency; C.V. = coefficient of variation. In relation to ASM, a chemical activator of plant defense mechanisms, there was no difference in relation to the control, corroborating with Silva et al. (2013) who found a similar result using ASM in soybeans, where the inducer also did not differ from the witness in relation to powdery mildew control. Although there is no effect in relation to powdery mildew, this product is promising in the control of nematodes in soybean culture (Da Rocha et al. 2000). Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 5 GABARDO, G., et al. Farmers have used chemical control frequently and there are several products registered for the control of this disease, among them we can mention those based on tebuconazole and azoxystrobin + cyproconazole. Application is recommended when the infection rate reaches 20% and make a maximum of 2 applications (ADAPAR 2020). Another control strategy is to consider the level of infection and stage of the soybean development when the infection level reaches 40 to 50% of the leaf area of the whole plant (Silva et al. 2007). In the experiment, the first application of fungicide occurred in R1, when there was a low disease severity (2.19%, in the first growing season and approximately 10.00% of severity in the second growing season) and the second application of fungicide was carried out in R5. 1 (powdery mildew severity of 22.46% in the first harvest and 40.58% in the second growing season) (Table 1), contributing to disease severity reduction in both growing seasons. Among the methods of disease control, genetic is the most efficient, and cultivars that are resistant to moderately resistant to fungus should be used. Another way to avoid losses by powdery mildew is not to sow susceptible cultivars in times more favorable to disease occurrence, such as late sowing or off-season and cultivation under irrigation in winter (Igarashi et al. 2014). The cultivar used is susceptible to powdery mildew and was sown late (in December), with the purpose of causing greater disease severity, which favored this in all thirds of the plant (Tables 1 and 2). Table 2. Area below the disease progress curve (AUDPG) of powdery mildew (Microsphaera diffusa) in the lower, middle and upper thirds and average in the whole plant depending on the alternative and fungicide treatments performed on soybean (Glycine max L.), cultivar BMX Potência RR. Ponta Grossa, PR, 2013/2014 and 2014/2015 growing seasons. Treatment 2013/2014 growing season AUDPG Lower third AUDPG Middle third AUDPG Upper third AUDPG Whole plant 1- Witness (water) 3065.76a* 1447.48a 437.33a 1650.19a 2- Acibenzolar-S-methyl 2787.22a 1053.33a 384.30a 1408.28a 3- Macronutrients: Ca 3109.11a 1282.57a 517.87a 1636.52a 4- Micronutrients: Cu; Mn; Zn 2876.86a 1139.39a 421.46a 1479.24a 5- Micronutrients: Mn; Zn; Mo 2830.61a 1120.24a 436.43a 1462.42a 6- NK fertilizer 2932.73a 1151.31a 486.55a 1523.53a 7- Ascophyllum nodosum 2792.77a 1358.58a 464.96a 1538.77a 8- azoxystrobin + cyproconazole 1074.65b 461.23b 105.85b 547.25b C.V. (%) 26.87 31.67 33.81 19.27 Treatment 2014/2015 growing season AUDPG Lower third AUDPG Middle third AUDPG Middle third AUDPG Whole plant 1- Witness (water) 2276.26a* 1196.36a 404.56a 1292.39a 2- Acibenzolar-S-methyl 2180.36a 1071.53a 365.37a 1205.76a 3- Macronutrients: Ca 2305.22a 1141.48a 325.94a 1257.55a 4- Micronutrients: Cu; Mn; Zn 2159.89a 1082.33a 388.75a 1210.33a 5- Micronutrients: Mn; Zn; Mo 2217.03a 1139.62a 342.12a 1232.92a 6- NK fertilizer 2248.77a 1163.67a 306.75a 1239.73a 7- Ascophyllum nodosum 2224.35a 1266.99a 346.60a 1279.31a 8- azoxystrobin + cyproconazole 991.85b 328.41b 93.29b 471.18b C.V. (%) 27.05 33.76 36.56 23.60 *Averages followed by the same lowercase letter in the column do not differ by the Scott-Knott test at 5% significance; C.V. – coefficient of variation. This fungus is a mandatory parasite that develops throughout the aerial part of soybeans, such as leaves, stems, petioles, and pods (rarely observed), but it is more visible in leaves and stems (Mian et al. 2016). The most affected leaves were those of the lower third, and in this third, the values of AUDPG's were higher than the plant other thirds in both growing season (Table 2). According to Igarashi et al. (2014) it is essential to prevent the entry of diseases that may eventually cause premature defoliation, especially those in the lower third of the plant, where the infectious process normally starts, that is, the entry of the fungus into the plant caused mainly after the closure of the lines, Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 6 Alternative products to control powdery mildew in soybeans culture in field which hinders the penetration of products in the canopy of the culture, also favoring a greater number of hours of watering due to the formation of a microclimate favorable to the development of diseases. Regarding AUDPGs, presented, only the treatment with fungicide differed from other treatments, showing a reduction in the value of AUDPG in the entire plant, in relation to the control of 66.84% and 63.54%, in 2013/2014 and 2014/2015 respectively (Table 2). Soy powdery mildew is a sporadic and potentially important disease in soybean crops, which can cause damage of up to 40% in yield of susceptible cultivars (Yulia et al. 2017). These damages are due to the removal of nutrients from the cells by intracellular haustoria, the fungus interference in the process of photosynthesis by decreasing the amount of light on the leaves surface that can reduce more than half the photosynthetic activity, in addition to substantially reducing transpiration (Pereira et al. 2012). In the 2013/2014 growing season (Table 3) the average control yield was 1,400.81 kg ha-1 and in the presence of alternative products the maximum productivity achieved was 1,900.90 kg ha-1 in the treatment with micronutrients (copper, manganese and zinc), the maximum reached in the presence of fungicide was 3,025.72 kg ha-1. In relation to control, there was an increase of 53.70% in productivity, when fungicide was applied. The productivity achieved in the presence of fungicide is close to the average productivity obtained in the State of Paraná 2,950.00 kg ha-1 and in São Paulo 3,100.00 kg ha-1 in the 2013/2014 harvest (CONAB, 2020). In the 2014/2015 growing season (Table 3) otherwise, the average control productivity was 1,308.28 kg ha-1 and in the presence of alternative products the maximum productivity achieved was 1,529.01 kg ha- 1, however the maximum achieved in the presence of fungicide was 2,303.46 kg ha-1. The productivity obtained in the presence of the fungicide are below the average yield of the cultivar obtained in the State of Paraná of 3,043.00 kg ha-1 and in São Paulo 3,010.00 kg ha-1 in the 2014/2015 growing seasons (CONAB, 2020). When the fungicide was applied, it avoided 43.20% of damage to productivity compared to the control. Table 3. Productivity (kg ha-1) as a function of alternative and fungicide treatments performed on soybean (Glycine max L.), cultivar BMX Potência RR. Ponta Grossa, PR, 2013/2014 and 2014/2015 growing seasons. Treatment 2013/2014 growing season 2014/2015 growing season 1- Witness (water) 1400.81b* 1308.28b 2- Acibenzolar-S-methyl 1716.89b 1325.49b 3- Macronutrients: Ca 1667.86b 1334.22b 4- Micronutrients: Cu; Mn; Zn 1900.90b 1529.01b 5- Micronutrients: Mn; Zn; Mo 1737.70b 1307.56b 6- NK fertilizer 1580.71b 1310.18b 7- Ascophyllum nodosum 1453.11b 1278.73b 8- azoxystrobin + cyproconazole 3025.72a 2303.46a C.V. (%) 12.13 10.27 *Averages followed by the same lower-case letter in the column do not differ by the Scott-Knott test at 5% significance; C.V. – coefficient of variation. Carvalho et al. (2013), obtained similar results in soybean culture, where productivity in the treatment with ASM, with 3 applications was 1160.90 kg ha-1, not different from the control with 1195.90 kg ha-1 and the treatment with fungicide (azoxystrobin + cyproconazole) differed from the control presented the highest productivity of 2142.2 kg ha-1. Silva et al. (2013) reported that treatment with ASM (12.5 g c.p. ha-1) associated with the fungicide (pyraclostrobin + epoxiconazol (66.5 + 25 g c.p. ha-1)) in soybean avoided damage to productivity. However, in this work, in relation to the isolated application of ASM (25 g c.p. ha-1) at a higher dose, there were no differences in productivity (Table 3). Work like Carvalho et al. (2013), confirm that only fungicide treatments prevented damage to productivity. Contradicting these authors, Silva et al. (2013), found greater productivity when they used ASM resistance inducer in soybean culture. Dallagnol et al. (2006) using the cultivars IAS-5, Coodetec 201 (CD 201) and Fepagro RS-10 (RS 10), with foliar application of ASM (50 g c.p. ha-1), observed that the cultivar IAS-5 and RS 10 showed no difference in relation to the productivity obtained. Only cultivar CD 201 showed a positive response of 9.2% in yield. Bioscience Journal | 2021 | vol. 37, e37052 | https://doi.org/10.14393/BJ-v37n0a2021-53681 7 GABARDO, G., et al. Comparing the work of Dallagnol et al (2006) with the present study, the data indicate different responses in relation to the cultivars, a fact that could explain the fact that the cultivar tested in this study does not respond to the application of the ASM. There was no significant difference in productivity using micro and macronutrients (Table 3). According to Bhardwaj et al. (2014) each of the macronutrients and micronutrients plays at least one function within the plant and its deficiency or excess causes characteristic deficiency or toxicity symptoms. Influencing not only growth and productivity, but also increasing its resistance to pathogens (Altieri and Nicholls 2003). Once incorporated into plant tissues, mineral nutrients become components or enzyme activators, or regulators of the degree of protoplasm hydration and, by extension, of the biological activity of proteins (Shittu et al. 2021). They can participate in the synthesis of compounds used in physical and or chemical barriers to microorganisms. Thus, the mineral nutrition of plants largely determines their resistance or susceptibility to various diseases (Carré-Missio et al. 2009). The use of biofertilizers, for example, has been indicated for organic agriculture as a way of maintaining the nutritional balance of plants and making them less predisposed to the occurrence of pests and pathogens (Rodrigues et al. 2016; Gabardo et al. 2020). Future experiments are necessary. Thus, associating the spraying of alternative products with fungicides, as Dallagnol et al. (2006), Santos et al. (2011) and Silva et al. (2013) demonstrated, can increase efficiency of fungicides when associated with inducers in disease control in soybean, wheat and soybean, respectively. This may contribute to a more satisfactory result, in addition to reducing the risk of selecting isolates resistant to fungicides and contributing to reducing the environmental impact. 4. Conclusions In both growing seasons, the alternative products tested had no effect on control of powdery mildew of soybean. The fungicide (azoxystrobin + cyproconazole) was the only one that controlled powdery mildew and prevented damage to productivity in both growing seasons. Authors' Contributions: GABARDO, G.: conception and design, acquisition of data, analysis and interpretation of data, and drafting the article; DALLA PRIA, M.: conception and design, and drafting the article; DA SILVA, H.L.: acquisition of data, analysis and interpretation of data, and critical review of important intellectual content; HARMS, M.G.: acquisition of data, analysis and interpretation of data. All authors have read and approved the final version of the manuscript. Conflicts of Interest: The authors declare no conflicts of interest. Ethics Approval: Not applicable. Acknowledgments: The authors would like to thank the funding for the realization of this study provided by the Brazilian agency CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil), Finance Code 001. References ADAPAR - Agência de defesa agropecuária do Paraná. Priori Xtra. 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KnE Life Sciences. 2017, 2(6), 270-278. https://doi.org/10.18502/kls.v2i6.1049 Received: 9 April 2020 | Accepted: 4 October 2020 | Published: 15 September 2021 This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestr icted use, distribution, and reproduction in any medium, provided the original work is properly cited. https://doi.org/10.5433/1679-0359.2011v32n2p433 https://doi.org/10.1094/Phyto-67-1051 https://doi.org/10.15414/jmbfs.2019.9.2.314-319 https://doi.org/10.1017/S0021859615000313 https://doi.org/10.1590/S0100-204X2007000900007 https://doi.org/10.1590/S1982-56762013000100012 https://doi.org/10.1590/0100-5405/168479 https://usdasearch.usda.gov/search?utf8=%E2%9C%93&affiliate=usda&query=soybean&commit=Search https://doi.org/10.1590/0100-5405/1923 https://doi.org/10.18502/kls.v2i6.1049