Published in Agron. J. 96:665-670 (2004).
© American Society of Agronomy
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PRODUCTION PAPERS
Management of Angular Leaf Spot in Common Bean (Phaseolus vulgaris L.) with Molybdenum and Fungicide
Waldir Cintra de Jesus, Jr.*,a,b,
Francisco Xavier Ribeiro Valea,
Reginaldo Resende Coelhoa,
Bernhard Hauc,
Laércio Zambolima and
Richard D. Bergerd
a Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa-MG 36571-000, Brazil
b Current address: Departamento de Entomologia, Fitopatologia e Zoologia Agrícola, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba-SP 13418-900, Caixa Postal 09, Brazil
c Institut fur Pflanzenkrankheiten und Pflanzenschutz, Universitat Hannover, Hannover 30419, Germany
d Plant Pathol. Dep., Univ. of Florida, Gainesville, FL 32611-0680
* Corresponding author (wcjesus{at}esalq.usp.br).
Received for publication December 18, 2002.
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ABSTRACT
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The yield of common bean (Phaseolus vulgaris L.) is affected by several factors, including diseases such as angular leaf spot (Phaeoisariopsis griseola) and N deficiency caused by lack of nodulation. In Minas Gerais State, Brazil, farmers have been using both fungicide and molybdenum (Mo) applications to improve crop yield. The objective of this research was to investigate the effect of Mo application in conjunction with variably applied fungicide on common bean in the management of angular leaf spot (ALS). Field experiments were conducted in two seasons, wet and dry, with eight fungicide treatment schedules, with and without Mo. Angular leaf spot severity, plant growth, photosynthesis, and yield were measured. A single application of Mo 25 d after sowing (DAS) decreased the area under the disease progress curve by 38% and increased the area under the leaf area progress curve by 20%, leaf photosynthesis by 26%, and yield by 51%. When combined with the Mo applications, fungicide spray applied once (at an early growth stage) or twice in the bean flowering period (25–45 DAS) should provide substantial control of ALS.
Abbreviations: ALS, angular leaf spot • AUDPC, area under disease progress curve • AULAPC, area under leaf area progress curve • DAS, days after sowing
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INTRODUCTION
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COMMON BEAN has good potential to fix N2; however, poor nodulation, especially under field conditions, has led to increased use of N fertilizer applications in this crop. Use of mineral N is expensive, and its continuous application creates environmental risks (Skiba et al., 1993). Alternative methods have been developed to minimize the amount of N applied, e.g., foliar application of Mo (Robitaille, 1975). Previously, high bean yields (1500–2500 kg ha–1) were obtained in the southeastern region of Brazil, either by applying N as a sidedressing or a Mo spray at 25 d after planting (Robitaille, 1975; Junqueira Netto et al., 1977; Vieira et al., 1992; Amane et al., 1994; Rodrigues et al., 1996). Foliar application of Mo increases acetylene reduction activity, nitrate reductase activity, and N remobilization during the pod-filling stage (Vieira et al., 1998a, 1998b). The combined effect of these processes results in higher grain yields. However, the scope of these effects varies with soil characteristics (Andrade et al., 1999; Araújo et al., 1999; Bassan et al., 1999; Soratto et al., 1999a, 1999b; Vieira et al., 1999).
Besides the increase in yield, few reports have associated Mo with response of plants to diseases (Graham, 1983). Dutta and Bremmer (1981) and Miller and Becker (1983) showed that Mo reduced by 18 to 37% the symptoms of Verticillium wilt in tomato (Lycopersicon esculentum Mill.). In other studies, Mo inhibited zoosporangia formation by Phytophthora cinnamomi and P. dreschleri (Halsall, 1977), and its application to the soil decreased nematode populations (Haque and Mukhopadhyaya, 1983). How Mo impacts on plant protection remains unclear. However, the requirement for Mo by nitrogenase and nitrate reductase is essential to mediate and enhance N metabolism (Marschner, 1986). It could be a strong reason to associate Mo with plant response to diseases.
Angular leaf spot of bean, caused by Phaeoisariopsis griseola (Sacc.) Ferraris, is a disease of worldwide occurrence. It has recently become one of the main problems in bean crops in Brazil. The pathogen causes lesions on the leaves, pods, branches, and petioles and may cause severe defoliation. In the absence of adequate control measures, yield reductions of 70% in Brazil (Jesus et al., 2001a) and 80% in Colombia (Schwartz et al., 1981) have been reported.
Chemical control is an important option in the management of bean diseases because of the widespread occurrence of these foliar diseases and the susceptibility of the available cultivars. Fungicides reduce the incidence and severity of disease and increase yield (Issa et al., 1982; Rodrigues et al., 1987; Barros et al., 1992). Studies are required to determine the effect of the time and numbers of sprays within a bean disease management program. Barros et al. (1992) studied the effect of the number of applications of the fungicide mancozeb {[[2-[(dithiocarboxy)amino]ethyl]carbamodithioato]](2–)-
S, S'] manganese mixture with [[2-[(dithiocarboxy)amino]ethyl]carbamodithioato]](2–)-S,S']zinc} at different periods and concluded that the best control of bean diseases and highest yield were obtained with seven applications of the chemical product, beginning at 20 d after plant emergence at 10-d intervals. Castro et al. (1989) observed that six applications of fungicide at intervals of 10 d provided similar results. Published literature on these important aspects of bean disease management is rare; more studies are necessary to identify the best time and most efficacious products for the control of bean diseases.
Two experiments were performed with common bean to determine the efficacy of foliar spray of Mo along with fungicide sprays at different periods for controlling ALS disease and to determine their effect on plant growth and yield. As common bean is one of the most important crops in the Americas, a low-cost management system of ALS is urgently needed to sustain bean production while minimizing environmental pollution.
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MATERIALS AND METHODS
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Field Experiments
Two experiments were performed at the Universidade Federal de Viçosa, Viçosa, Minas Gerais State, Brazil, from October to December 1998 and from March to May 1999. The bean cultivar Carioca was used to study how Mo sprayed on the bean foliage influences the progress of ALS as well as plant growth and yield. Furthermore, the effect of Mo on disease development (area under disease progress curve, AUDPC), plant growth (area under leaf area progress curve, AULAPC), photosynthesis (net photosynthetic rate), and yield was evaluated.
Effect of Mo and fungicide on those variables was examined in a split-plot design with fungicide schedule as main plots and Mo (with and without) as subplots in four replications in the first trial and three replications in the second trial. Each experimental block (24 m2) consisted of eight 6-m-long rows, spaced 0.5 m apart. Twelve seeds were sown, and 10 plants were allowed to grow per meter of row. The plots were maintained with the conventional cultural practices used in commercial fields, including planting and topdressing with fertilizer, insecticide sprays, weeding, and sprinkle irrigation when necessary. The fungicide treatments with tebuconazole {
-[2-(4-chlorophenyl)ethyl]--(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol} to control ALS were adjusted to different stages of plant growth: (i) no spray, (ii) spray 25 DAS, (iii) spray 35 DAS, (iv) spray 45 DAS, (v) spray 25 and 35 DAS, (vi) spray 25 and 45 DAS, (vii) spray 35 and 45 DAS, and (viii) spray 25, 35, and 45 DAS. Tebuconazole was sprayed on bean plants at 0.75 kg ha–1 (187.5 g a.i. ha–1). The days selected for spraying (25, 35, and 45 DAS) represented before, during, and after plant flowering. A backpack mistblower was used to apply sodium molybdate in solution (20 g Mo ha–1) as a subplot treatment to the main plots on the bean foliage 25 DAS.
The soils in both trials were analyzed. For the respective experiments, the pH in water was 5.6 and 6.5; available P, 4.3 and 4.8 mg dm–3; available K, 62.0 and 70.0 mg dm–3; Ca2+ exchange capacity, 1.4 and 1.8 cmolc dm–3; Mg2+ exchange capacity, 0.6 and 0.7 cmolc dm–3; and Al+3 exchange capacity, 0.0 and 0.0 cmolc dm–3. The Mo content in this soil was less than 0.2 mg kg–1, as determined in previous experiments in this area, which is lower than the normal value of 0.5 to 5 mg kg–1 (Gupta and Lipsett, 1981).
Crop Growth, Disease Severity, Photosynthesis, and Yield
Crop growth and disease severity were evaluated weekly in the eight central rows of each plot (disregarding the 0.5 m at each end of the row). Beginning 25 DAS, in which the plant was in V3 growth stage (first trifoliolate leaf) (Van Schoonhoven and Pastor-Corrales, 1987), five randomly chosen plants were removed from each plot on each day of observation, giving a total of 160 per week for the first trial and 120 plants per week in the second trial. The total leaf area (cm2) of the five plants was determined with an area meter (Model LI-3100, LI-COR, Lincoln, NE, USA). Severity (%) of ALS was assessed with the aid of a standard area diagram (Godoy et al., 1997), and the average for the three leaflets of each leaf on all removed plants was estimated. Even though defoliation was observed, it was not quantified. The polybrachiate growth habit of cultivar Carioca made it difficult to identify specific leaves in sequential assessments. Thus, the total number, area, and original position of fallen leaves were not considered.
A LI-6400 Portable Photosynthesis System (LI-COR, Lincoln, NE, USA) with a leaf chamber of 6 cm2 was used to measure CO2 uptake, air temperature, and relative humidity. Two leaves at the same physiological state were sampled per plant, with five replications per plot. Measurements were made between 0800 and 1100 h, one for each leaf, at the central area of the main leaflet, using a photosynthetically active radiation (PAR) of 650 µmol m–2 s–1. Results were expressed as net photosynthetic rates (µmol m–2 s–1). All evaluations were made weekly only on days under clear weather conditions. Yield was determined for each plot (kg plot–1) by weighing the seeds (with 12% moisture) at the end of each crop cycle.
Integral Variables
The AUDPC and AULAPC values for each plant were calculated by trapezoidal integration, as described by Campbell and Madden (1990):
where n is the number of assessments, X is the disease severity of ALS (in percentage), LA is the leaf area (cm2) per plant, and (ti+1 – ti) is the interval between two consecutive assessments.
Data Analysis
Analysis of variance (ANOVA) was conducted using the Statistica 6.0 system (StatSoft, Tulsa, OK, USA) by the procedure of contrast analysis. Least significant differences of means (0.05 level) were used to compare treatments.
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RESULTS AND DISCUSSION
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Significant differences were found for AUDPC, AULAPC, net photosynthetic rate, and yield between treatments that received Mo and those that did not. The Mo treatments had smaller values for AUDPC (Fig. 1A and 1B)
but higher values for AULAPC (Fig. 1C and 1D), net photosynthetic rate (Fig. 1E and 1F), and yield (Fig. 1G and 1H) than the treatments without Mo. These results corroborate those of other authors on the increase in yield and leaf area (Robitaille, 1975; Junqueira Netto et al., 1977; Vieira et al., 1992; Amane et al., 1994; Rodrigues et al., 1996) and on the decrease in disease (Halsall, 1977; Dutta and Bremmer, 1981; Graham, 1983; Haque and Mukhopadhyaya, 1983; Miller and Becker, 1983; Fernando et al., 1986) caused by the use of Mo.
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Fig. 1. Area under angular leaf spot progress curves (AUDPC, % d), area under leaf area progress curves (AULAPC, cm2 d), net photosynthetic rate (µmol CO2 m–2 s–1), and yield (kg plot–1) for the eight treatments, with and without Mo application, for the first and second trials. Vertical bars represent ± standard error.
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Treatments that received fungicide had less AUDPC than Treatment 1 (unsprayed) (Table 1) (Fig. 1A and 1B). Analyses of AULAPC, net photosynthetic rate, and yield (Fig. 1C and 1D, 1E and 1F, and 1G and 1H, respectively) showed that higher leaf area and greater net photosynthetic rate and yield were associated with better disease control (Table 1). The reduction in leaf area observed in the treatments with higher disease levels was caused by the defoliating effect of ALS (Carneiro et al., 1997; Silva et al., 1998; Jesus et al., 2001a). In addition, ALS causes a lesion in the leaf, with necrotic and yellowing areas, in which the photosynthesis is lower than a healthy area (Bassanezi et al., 2001). Jesus et al. (2001b) observed that the inoculation of bean plants with P. griseola reduced net photosynthetic rate by 17% and yield by 70%. According to these authors, the effect of the pathogen on yield reduction could be explained in part by decreases in stomatal conductance and net photosynthetic rate of diseased bean leaves.
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Table 1. Area under disease progress curve (AUDPC), area under leaf area progress curve (AULAPC), net photosynthetic rate, and yield of common bean without Mo application and treated with fungicide tebuconazole at different plant growth stages.
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Significant effect of combining Mo application and chemical control was observed on all variables (Table 2). To clarify the magnitude of the data, values of yield and net photosynthetic rate for treatments where interactions were statistically significant (0.05 level by the LSD of means) at the first trial were presented (Fig. 2)
. Related to the yield, the average of treatments that had not received Mo at the first trial was 2.72 kg plot–1. On the other hand, treatments that received Mo had yield average of 3.21 kg plot–1, which corresponds to an increase of 0.49 kg plot–1.
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Table 2. Area under disease progress curve (AUDPC), area under leaf area progress curve (AULAPC), net photosynthetic rate, and yield of common bean with Mo application and treated with fungicide tebuconazole at different plant growth stages.
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Fig. 2. Yield (kg plot–1) and net photosynthetic rate (µmol CO2 m–2 s–1) of bean for treatments where interactions were statistically significant at the first trial. (A) Bars are LSD to compare (a) between T25 levels (Treatment 2) and (b) within T25 level; (B) bars are LSD to compare (a) between T45 levels (Treatment 4) and (b) within T45 level; (C) bars are LSD to compare (a) between T35 levels (Treatment 3) and (b) within T35 level.
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The plots sprayed with fungicide 25 and 45 DAS and that received Mo application had higher yields than the other treatments (0.05 level by the LSD of means) (Fig. 2A and 2B). Contrarily, the net photosynthetic rate was higher on treatments that received fungicide 35 DAS than the other treatments (0.05 level by the LSD of means) (Fig. 2C). For ALS control, Barros et al. (1992) demonstrated that the best control of the disease was obtained by spraying at 20, 35, and 50 d after plant emergence. In the former treatments, plots of our work each received a spray at 25 and/or 45 DAS. Thus it is essential to spray bean foliage one or two times during the interval of 25 to 45 DAS to control ALS. Probably the significance of this finding could be ascribed to the fact that the flowering stage occurs during this interval (25–45); thus, protecting the foliage against disease attack translates to increased yield.
The differences observed following Mo application probably occurred because Mo functions as a micronutrient. Molybdenum ions are components of several enzymes, including nitrate reductase and nitrogenase (Taiz and Zeiger, 1998). Nitrate reductase catalyzes the reduction of nitrate to nitrite during its assimilation by the plant cell. Nitrogenase converts N2 to NH3 in N-fixing microorganisms. The effect of Mo on fungal pathogens and diseases is not clear, but this micronutrient may induce resistance in the plant against pathogens. More studies are necessary to elucidate the role of this micronutrient in plant disease control.
The combination of chemical control (sprayed one or two times during the interval of 25 to 45 DAS) and Mo application (25 DAS) on bean foliage enhanced plant growth and improved control of ALS. Molybdenum sprays can be used in a management system for ALS with little increase in production costs because of the low price of the salt (sodium molybdate) and the low dosage needed.
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ACKNOWLEDGMENTS
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This research was partially supported by the European Commission (project ERBIC18CT96-0037), FINEP, and FAPEMIG. CAPES supported the first author. We thank Ruth Butler and Tracy Williams, Crop & Food Research, Lincoln, New Zealand, for statistical analysis and editing, respectively.
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REFERENCES
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- Amane, M.I.V., C. Vieira, A.A. Cardoso, and G.A.A. Araújo. 1994. Resposta de cultivares de feijão (Phaseolus vulgaris L.) às adubações nitrogenada e molíbdica. Rev. Ceres 41:202–216.
- Andrade, C.A.B., J.C. Pintro, C.A. Scapim, and E.B. Santos. 1999. Efeitos de doses de molibdênio no rendimento e nutrição de duas cultivares de feijão. Reun. Nac. Feijão 6:801–804.
- Araújo, P.R.A., L.R. Ferreira, G.A.A. Araújo, and J.M. Gomes. 1999. Eficácia da aplicação de molibdênio em mistura no tanque com herbicidas pós-emergentes sobre o feijoeiro. Reun. Nac. Feijão 6:480–483.
- Barros, B.C., J.L. Castro, S.H.F. Oliveira, and D.A. Oliveira. 1992. Efeito do número de aplicações de mancozeb em diferentes épocas no controle de doenças e no rendimento do feijoeiro (Phaseolus vulgaris). Summa Phytopathol. 18:276–282.
- Bassan, D.A.Z., O. Arf, S. Buzetti, N.C.B. Santos, and M.A.C. Carvalho. 1999. Efeito da inoculação de sementes e aplicação de nitrogênio e molibdênio sobre a produção de feijão (Phaseolus vulgaris L.) no período de inverno. Reun. Nac. Feijão 6:785–787.
- Bassanezi, R.B., L. Amorim, A. Bergamin Filho, B. Hau, and R.D. Berger. 2001. Accounting for photosynthetic efficiency of leaves with rust, angular leaf spot and anthracnose to assess crop damage. Plant Pathol. 50:443–452.
- Campbell, C.L., and L.V. Madden. 1990. Introduction to plant disease epidemiology. John Wiley, New York.
- Carneiro, S.M.T.P.G., L. Amorim, and A. Bergamin Filho. 1997. Avaliação de dano provocado pela mancha angular em feijoeiro: Relação entre severidade, área foliar e componentes de produção. Fitopatol. Bras. 22:427–431.
- Castro, J.L., C. Dudienas, M.F. Ito, and T. Igue. 1989. Eficiência de fungicidas no controle das doenças do feijoeiro (Phaseolus vulgaris). Summa Phytopathol. 15:145–155.
- Dutta, B.K., and E. Bremmer. 1981. Trace elements as plant chemotherapeutants to control Verticillium wilt. Z. Pflanzenkrankh. Pflanzenschutz 88:405–412.
- Fernando, T., B.B. Jarvis, and G. Bean. 1986. Effects of micro-elements on production of roridin E by Mirothecium roridum, a strain pathogenic to muskmelon (Cucumis melo). Trans. Br. Mycol. Soc. 86:273–277.
- Godoy, C.V., S.M.T.P.G. Carneiro, M.T. Iamauti, M. Dalla Pria, L. Amorim, R.D. Berger, and A. Bergamin Filho. 1997. Diagrammatic scales for bean diseases: Development and validation. Z. Pflanzenkrankh. Pflanzenschutz 104:336–345.
- Graham, R.D. 1983. Effect of nutrient stress on susceptibility of plants to disease with particular reference to the trace elements. Adv. Bot. Res. 10:221–276.
- Gupta, U.C., and J. Lipsett. 1981. Molybdenum in soil, plant and animals. Adv. Agron. 34:73–115.
- Halsall, D.M. 1977. Effects of certain cations on the formation and infectivity of Phytophthora zoospores: II. Effects of copper, boron, cobalt, manganese, molybdenum and zinc ions. Can. J. Microbiol. 23:1002–1010.[Medline]
- Haque, M.S., and M.C. Mukhopadhyaya. 1983. Influence of some micro-nutrients on Rotylenchus reniformis. Indian J. Nematol. 13:115–116.
- Issa, E., C. Sinigaglia, and D. A. Oliveira. 1982. Controle químico da mancha angular da folha, Isariopsis griseola Sacc., do feijoeiro, Phaseolus vulgaris L. O Biológico 48:299–303.
- Jesus, W.C., Jr., F.X.R. Vale, R.R. Coelho, B. Hau, L. Zambolim, L.C. Costa, and A. Bergamin Filho. 2001a. Effects of angular leaf spot and rust on yield loss of Phaseolus vulgaris. Phytopathology 91:1045–1053.[Medline]
- Jesus, W.C., Jr., F.X.R. Vale, C.A. Martinez, R.R. Coelho, L.C. Costa, B. Hau, and L. Zambolim. 2001b. Effects of angular leaf spot and rust on leaf gas exchange and yield of common bean (Phaseolus vulgaris). Photosynthetica 39:603–606.
- Junqueira Netto, A., O.S. Santos, H. Aidar, and C. Vieira. 1977. Ensaios preliminares sobre a aplicação de molibdênio e de cobalto na cultura do feijão (Phaseolus vulgaris). Rev. Ceres 24:628–633.
- Marschner, H. 1986. Mineral nutrition of higher plants. Academic Press, London.
- Miller, V.R., and Z.E. Becker. 1983. The role of microelements in cotton resistance to Verticillium wilt. Sel'skokhoz. Biol. 11:54–56.
- Robitaille, H.A. 1975. Effect of foliar molybdenum sprays on nitrogen fixation in Phaseolus vulgaris L. Annu. Rep. Bean Improv. Coop. 18:65.
- Rodrigues, J.R.M., M.J.B. Andrade, and J.G. Carvalho. 1996. Resposta de cultivares de feijão (Phaseolus vulgaris) a doses de molibdênio aplicadas via foliar. Ciênc. Agrotécnica 20:323–333.
- Rodrigues, C.H., L. Zambolim, and M.C.D.P. Martins. 1987. Eficiência de fungicidas no controle da mancha angular (Isariopsis griseola) do feijoeiro (Phaseolus vulgaris). Fitopatol. Bras. 12:40–45.
- Schwartz, H.F., V. Correa, D.P.A. Pineda, M.M. Otoya, and M.J. Katherman. 1981. Dry bean yield losses caused by Ascochyta, angular and white leaf spots in Colombia. Plant Dis. 65:494–496.
- Silva, M.B., F.X.R. Vale, L. Zambolim, and B. Hau. 1998. Efeitos da ferrugem, da antracnose e da mancha angular na área foliar de plantas de feijoeiro em condições de campo. Fitopatol. Bras. 23:442–447.
- Skiba, U., K.A. Smith, and D. Fowler. 1993. Nitrification and denitrification as sources of nitric oxide in a sandy loam soil. Soil Biol. Biochem. 25:1527–1536.
- Soratto, R.P., T.R.B. Silva, S.N. Chidi, O. Arf, and S. Buzetti. 1999a. Resposta do feijoeiro (Phaseolus vulgaris L.) à aplicação de nitrogênio em cobertura e molibdênio via foliar: I. Características agronômicas. Reun. Nac. Feijão 6:854–857.
- Soratto, R.P., T.R.B. Silva, S.N. Chidi, O. Arf, and M.E. Sá. 1999b. Resposta do feijoeiro (Phaseolus vulgaris L.) à aplicação de nitrogênio em cobertura e molibdênio via foliar: II. Qualidade fisiológica das sementes. Reun. Nac. Feijão 6:595–598.
- Taiz, L., and E. Zeiger. 1998. Plant physiology. Sinauer Associates, Sunderland, MA.
- Van Schoonhoven, A., and M.A. Pastor-Corrales. 1987. Sistema estándar para la evaluación de germoplasma de frijol. CIAT, Cali, Colombia.
- Vieira, C., A.O. Nogueira, and A. Araújo. 1992. Adubação nitrogenada e molíbdica na cultura do feijão. Rev. Agríc. (Piracicaba, Braz.) 67:117–124.
- Vieira, R.F., E.J.B.N. Cardoso, C. Vieira, and S.T.A. Cassini. 1998a. Foliar application of molybdenum in common beans: I. Nitrogenase and nitrate reductase activities in a soil of high fertility. J. Plant Nutr. 21:169–180.
- Vieira, R.F., C. Vieira, E.J.B.N. Cardoso, and P.R. Mosquim. 1998b. Foliar application of molybdenum in common bean: II. Nitrogenase and nitrate reductase activities in a soil of low fertility. J. Plant Nutr. 21:2141–2151.
- Vieira, S.M., P. Ronzelli Júnior, H.S. Koehler, and B.M.S. Prevedello. 1999. Nitrogênio, molibdênio e inoculante, isolados e associados para duas variedades de feijoeiro-comum. Reun. Nac. Feijão 6:835–838.
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ABSTRACT
INTRODUCTION
