Subscribe Now Subscribe Today
Abstract
Fulltext PDF
References
Research Article
 
Management of Leaf Spot Diseases of Peanut with Fungicides and Local Detergents in Ghana



S.K. Nutsugah , M. Abudulai , C. Oti-Boateng , R.L. Brandenburg and D.L. Jordan
 
ABSTRACT

Early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum) of peanut (Arachis hypogaea) are a major constraint to peanut production in northern Ghana. To develop suitable disease management options, field trials were conducted from 2003 to 2005 at Nyankpala, Yendi and Damongo to compare the efficacy of the fungicides thiophanate methyl, benomyl and tebuconazole and the local detergents black soap and alata samina either alone or as a mixture. Final leaf spot ratings were recorded 72 days after sowing while biomass and pod yields were recorded at harvest. Leaf spot ratings, biomass and pod yields in local detergents and untreated control treatments did not differ across the three locations in 2003. However, fungicides suppressed disease and increased biomass and pod yields. In 2004 and 2005, leaf spot severity was reduced and biomass and pod yields increased compared to untreated control when local detergents were applied in combination or alternation with fungicides. Tebuconazole applied alone was the most effective fungicide in reducing leaf spot severity, resulting in significantly higher biomass and pod yields compared to most of the treatments.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

S.K. Nutsugah , M. Abudulai , C. Oti-Boateng , R.L. Brandenburg and D.L. Jordan , 2007. Management of Leaf Spot Diseases of Peanut with Fungicides and Local Detergents in Ghana. Plant Pathology Journal, 6: 248-253.

DOI: 10.3923/ppj.2007.248.253

URL: https://scialert.net/abstract/?doi=ppj.2007.248.253

INTRODUCTION

Peanut (Arachis hypogaea L.) is an important legume that increases the diversity of the cereal-based cropping systems of the savanna zone of Ghana. It is used extensively as a source of cooking oil and in confectionery products for human consumption. Peanut hay (vine) constitutes important fodder resources for livestock production and fodder trading in northern Ghana, particularly in the dry season when green forage is not available (Tsigbey et al., 2004; Naab et al., 2005).

During the 2003 cropping season, 439030 metric tons of peanut was produced in Ghana from a land area of 464710 ha (Statistics, Research and Information Directorate (SRID), 2004). The northern sector (Northern, Upper West and Upper East Regions) produced 91.4% of the national production (SRID, 2004). Pod yield of peanut crops in Ghana averages only 840 kg ha-1, which is low compared to yields of 2500 kg ha-1 in developed countries (FAO, 2002). The low yields in Ghana and other parts of West Africa are particularly attributed to foliar diseases. Early leaf spot caused by Cercospora arachidicola Hori and late leaf spot caused by Cercosporidium personatum (Berk. and Curt) Deighton, are among the major diseases of peanut worldwide, including West Africa (Subramanyam et al., 1991; Waliyar et al., 2000). Leaf spot can cause yield losses of 50-70% in West Africa (Waliyar, 1991; Waliyar et al., 2000; Naab et al., 2004) and up to 50% worldwide (McDonald et al., 1985). The yield losses caused by leaf spot are mainly because of decrease in photosynthetic leaf area caused by necrotic spots and defoliation (Boote et al., 1980; Bourgeois and Boote, 1992; Naab et al., 2005). Loss of mature pods due to leaf spot damage to pegs can also lead to yield losses during harvest. Both early and late leaf spot diseases are widely distributed and occur in epidemic proportions in northern Ghana. Annual yield losses of up to 50% are common over wide areas of the region (Nutsugah et al., 1998, 2006; Tsigbey et al., 2001).

Farmers in northern Ghana are not aware that leaf spot cause defoliation and perceive leaf loss as a symptom of maturity. Further, they do not use disease control measures in peanut cultivation. Therefore, it is necessary to develop suitable crop management practices for peanut crops in Ghana. A few studies in West Africa have shown that application of fungicide can reduce the severity of leaf spot and improve peanut yields (Kannaiyan and Haciwa, 1990; Waliyar et al., 2000). In many West African countries including Ghana, use of fungicidal sprays is not common due to lack of credit, low yield potential under rainfed conditions and difficulty in obtaining fungicides (McDonald et al., 1985). Our earlier studies showed the benefits of fungicide application on peanut yields under the rainfed and presumed low yield potential production in Ghana (Nutsugah et al., 1998, 2006; Tsigbey et al., 2000, 2001). Previous attempts for the management of peanut leaf spot diseases in northern Ghana from 1997 to 2002 indicated that neem seed extract (20%, w/v), alata samina (2.5%, w/v), thiophanate-methyl (0.35 kg a.i. ha-1), carbendazim (Bavistin, 0.3 kg a.i. ha-1), tebuconazole (Folicur 3.6F, 0.22 kg a.i. ha-1) mixed with azoxystrobin (Abound 2.08F, 0.45 kg a.i. ha-1) effectively reduced leaf spots severity and maximized peanut yield (Nutsugah et al., 1998; Tsigbey et al., 2000, 2001). In the southeastern United States, leaf spot diseases have been managed with multiple applications of fungicides (Culbreath et al., 2002).

In the search for effective and safe fungicides, benomyl was tested for the first time with the already known fungicides in combination with local detergent in the hope of improving the efficiency of leaf spots control in peanut in northern Ghana.

MATERIALS AND METHODS

Experimental details: Research was conducted from 2003 to 2005 at the Savanna Agricultural Research Institute experimental sites at Nyankpala, Yendi and Damongo, which are representative peanut production sites in the Guinea Savanna zone. During the experimental period of three years, only peanut crop was grown during the season and fields remained fallow during the off-season. The cultivar Chinese (90 days duration) was grown for the three seasons. In 2003, the experiment was designed to evaluate efficacy of local detergents, black soap and alata samina at 2.5% w/v (0.375 kg 15 L-1) for the control of leaf spot diseases. The detergents are traditionally manufactured in Ghana from a blend of plantain peels, palm kernels and coconut oil. Both detergents have been analysed and found to possess antifungal activity against Candida albicans (Nutsugah and Gadzekpo, unpublished). The fungicides thiophanate methyl (Topsin-M 70% WP, Cerexagri, Inc., USA at 0.35 kg a.i. ha-1) and tebuconazole (Folicur 3.6F, Bayer CropScience, USA at 0.22 kg a.i. ha-1) were also used. Sowing dates in 2003 were 4 June, 8 July and 18 July at Nyankpala, Yendi and Damongo, respectively. During 2004 and 2005, the treatments were modified to include thiophanate methyl in combination with alata samina at 1.0% w/v (0.15 kg 15 L-1) and in alternation with alata samina at 2.5% w/v (0.375 kg 15 L-1). Thiophanate methyl was applied first and alternated with alata samina during the second round of application. Other treatments were benomyl (Benlate 350 WP, Du Pont, Wilmington, Delaware, USA at 0.2 kg ha-1) in combination with alata samina at 1.0% w/v (0.15 kg 15 L-1), tebuconazole and untreated control. Sowing dates were 7 June, 16 June and 24 June 2004 at Nyankpala, Yendi and Damongo, respectively. In 2005, the trial was conducted only at Nyankpala and the sowing date was 29 June. Fungicides and local detergents were applied at 14 day intervals starting at 30 days after sowing (DAS) using 15 L knapsack sprayer. Spray volume used was 150 L ha-1. A total of four sprays were made during each year. The experimental design was a randomized complete block with four replications. In each treatment, eight rows each of 4 m length were considered as a single replication with spacing of 10 cm between plants and 50 cm between the rows.

Data collection and analysis: Incidence of leaf spot was recorded starting from 30 DAS until harvest maturity and severity of leaf spot was rated on the Florida scale of 1-10 (Chiteka et al., 1997) based on visual observation. At optimum pod maturity, plants from the middle six 4 m long rows of each plot were hand-harvested and weight of the above-ground foliage and underground pods were determined. All the biomass and pod yields data are expressed in kilograms per hectare. Data were subjected to analysis of variance (Anonymous, 1998). Means were separated using Fisher’s Protected LSD at p≤0.05. Correlations were used to identify relations between disease scores, biomass and pod yields.

RESULTS

In 2003, leaf spot ratings varied with treatments and locations. Early leaf spot ratings were more severe at Yendi than Damongo and Nyankpala while late leaf spot ratings were lowest at Yendi (Table 1). Across locations, leaf spot ratings in local detergents black soap and alata samina were similar (p = 0.05) to or lower than the untreated control (Table 1). Thiophanate methyl and tebuconazole significantly (p = 0.05) lowered leaf spot ratings at all locations compared to other treatments. Application of fungicides consistently resulted in greater biomass and pod yields compared to detergents and untreated control (Table 1). Across locations, thiophanate methyl and tebuconazole increased both biomass and pod yields significantly (p = 0.05) compared to other treatments.

Table 1: Effect of local detergents and fungicides on disease score, biomass and pod yield at harvest of peanut cultivar Chinese at Nyankpala, Yendi and Damongo during 2003 rainy season
1:On the Florida scale of 1-10, where 1 = no leaf spot and 10 = plants completely defoliated and killed by leaf spot, 2: Fresh weight, 3: Sun-dried weight, 4:Local detergents rate was 2.5% w/v (0.375 kg 15 L-1) while fungicides rates were 0.35 kg a.i. ha-1 (thiophanate methyl) and 0.22 kg a.i. ha-1 (tebuconazole), 5:Mean of four replicates

Table 2: Effect of fungicides combinations with local detergent on disease score, biomass and pod yield at harvest of peanut cultivar Chinese at Nyankpala, Yendi and Damongo during 2004 rainy season
1: On the Florida scale of 1-10, where 1 = no leaf spot and 10 = plants completely defoliated and killed by leaf spot, 2: Fresh weight, 3: Sun-dried weight, 4:Local detergents rates were 1.0% w/v (0.15 kg 15 L-1) in combination and 2.5% w/v (0.375 kg 15 L-1) in alternation while fungicides rates were 0.35 kg a.i. ha-1 (thiophanate methyl), 0.2 kg ha-1 (benomyl) and 0.22 kg a.i. ha-1 (tebuconazole), 5: Mean of four replicates

In 2004, early leaf spot ratings were more severe at Nyankpala than Damongo and Yendi while late leaf spot ratings were lowest at Yendi (Table 2). Leaf spot ratings were significantly (p = 0.05) lower in fungicide combinations treatments than in the untreated control at all locations.

Table 3: Effect of fungicides combinations with local detergent on disease score, biomass and pod yield at harvest of peanut cultivar Chinese at Nyankpala during 2005 rainy season
1: On the Florida scale of 1-10, where 1 = no leaf spot and 10 = plants completely defoliated and killed by leaf spot, 2: Fresh weight, 3Sun-dried weight, 4: Local detergents rates were 1.0% w/v (0.15 kg 15 L-1) in combination and 2.5% w/v (0.375 kg 15 L-1) in alternation while fungicides rates were 0.35 kg a.i. ha-1 (thiophanate methyl), 0.2 kg ha-1 (benomyl) and 0.22 kg a.i. ha-1 (tebuconazole), 5Mean of four replicates

Similarly, tebuconazole alone lowered leaf spot ratings (p = 0.05) at all locations. Biomass and pod yields were greater among the fungicides combinations treatments than the untreated control across all locations (Table 2). Biomass and pod yields were significantly (p = 0.05) higher in the tebuconazole alone treatment than other treatments in Damongo and for pod yield at Nyankpala (Table 2). There were slight differences in biomass and pod yields among the three fungicides combinations treatments.

In 2005, the results for leaf spot ratings, biomass and pod yields followed the same trend as reported in 2004. Leaf spot ratings of 7.3 and 6.0 recorded for early and late leaf spot in untreated control at Nyankpala, respectively, were significantly (p = 0.05) higher than the other treatments (Table 3). Combinations of fungicides and alata samina or tebuconazole alone lowered leaf spot ratings. Biomass and pod yields were significantly (p = 0.05) higher in treatments that included fungicides compared to untreated control (Table 3). Among treated plots, tebuconazole alone and benomyl plus alata samina treatments produced significantly (p = 0.05) higher pod yields than the other treatments (Table 3).

Biomass yield was negatively correlated with early (R2 = 0.578, p<0.0001) and late (R2 = 0.563, p<0.0001) leaf spot ratings across locations. Similarly, pod yield was negatively correlated with early (R2 = 0.706, p<0.0001) and late (R2 = 0.423, p<0.0001) leaf spot ratings across locations. The results followed the same trend in 2004 and 2005.

DISCUSSION

Traditionally, farmers in northern Ghana do not use any management practices to control leaf spot and farmers generally associate canopy defoliation caused by leaf spot with optimum pod maturity (Naab et al., 2005). The CROPGRO-peanut model analysis (Naab et al., 2004) recommended fungicide trials in Ghana to document yield increases when fungicides are applied to peanut. The standard fungicide program for peanut growers in Georgia, US includes an initial application 30 days after sowing (DAS), followed by additional sprays at 14 day intervals, resulting in seven or more applications per season (Culbreath et al., 2002; Kemerait et al., 2005). Four applications of tebuconazole, the most effective fungicide in the present study, are known to reduce leaf spots severity and maximize peanut yield (Bowen et al., 1997). In our study, four sprays at 30, 44, 58 and 72 DAS were used to give comparable yields to those obtained in developed countries. Considerable efforts have been directed at fungicidal control of leaf spot diseases of peanut in northern Ghana. Tebuconazole mixed with azoxystrobin sprays resulted in decreased leaf spot rating and increased biomass and pod yields 2 to 3-fold each over untreated control (Tsigbey et al., 2001). Also, thiophanate methyl lowered leaf spot rating compared to alata samina, neem (Azadiractin indica) and untreated control (Tsigbey et al., 2001). Results from the present study corroborate previous reports that tebuconazole and thiophanate methyl are effective for leaf spot control in peanut. However, from our field tests that included a range of leaf spot ratings, mixtures of benomyl and alata samina have the potential to provide control of leaf spot diseases of peanut comparable to that achieved with tebuconazole. Combination of benomyl plus alata samina effects on leaf spot ratings and biomass and pod yields were consistent across the three locations and had the advantage among the three fungicides combinations treatments. The reason for mixing fungicides and local detergents in the field trials during 2004 and 2005 was to use it as spray adjuvant to improve the efficiency of leaf spot control in peanut. Results from our trials document the potential impact of utilizing fungicides to effectively manage foliar diseases in Ghana.

The variation in pod yields obtained in the different fungicide treatments compared to control seems to be not just because of reduced leaf spots severity. In 2003, the severity of late leaf spot in control and tebuconazole treatments at Nyankpala was 5.3 and 4.0, but the pod yield in these two treatments differed by 300%. The 3-fold increase in pod yield in the fungicide treatment was unlikely to be due solely to the slight decrease in disease, some other factors might have contributed. Leaf spot severity in the experimental fields varied over the three years. The variation can be explained by differences in the amount of rainfall during these years with mean rainfall of 968, 1429 and 1066 mm recorded at Nyankpala, Yendi and Damongo, respectively when averaged across years. Leaf spot severity is highly dependent upon weather, especially rainfall and associated canopy humidity (Shokes and Culbreath, 1997).

The negative relationships between early and late leaf spot ratings and biomass and pod yields observed across locations and years, suggest that both diseases are limiting factors in peanut productivity in northern Ghana. Yield advantages of the fungicide treatment intervention may be due to reduced biomass damage.

In conclusion, thiophanate methyl significantly increased pod yield over untreated control by 58% across locations in 2003 and tebuconazole by 56% over three years. The corresponding biomass increase was 63 and 55%, respectively for thiophanate methyl and tebuconazole. These data suggest that fungicides should be included in integrated management strategies for peanut to control early and late leaf spot. Additional research is needed to compare thiophanate methyl and benomyl plus detergent treatments and fungicide treatments to evaluate advantage of the detergent presence and also determine interactions of fungicide and detergent spray program and host-plant resistance in peanut production systems in northern Ghana.

ACKNOWLEDGMENTS

This research was supported in part by the United States Agency for International Development under the Peanut Collaborative Research Support Program (LAG-G-00-96-90013-00) and African Development Bank under the Food Crops Development Project (F/GHA/FOD-CRD-DEV/98/18). The authors are grateful to the field technical staff for their assistance.

REFERENCES
Anonymous, 1998. SAS/STAT User`s Guide, Version 8. SAS Institute, Cary, NC, USA.

Boote, K.J., J.W. Jones, G.H. Smerage, C.S. Barfield and R.D. Berger, 1980. Photosynthesis of peanut canopies as affected by leaf spot and artificial defoliation. Agron. J., 72: 247-252.

Bourgeois, G. and K.J. Boote, 1992. Leaflet and canopy photosynthesis of peanut affected by late leaf spot. Agron. J., 84: 359-366.
Direct Link  |  

Bowen, K.L., A.K. Hagan and J.R. Weeks, 1997. Number of tebuconazole applications for maximizing disease control and yield of peanut in growers fields in Alabama. Plant Dis., 81: 927-931.
CrossRef  |  

Chiteka, Z.A., D.W. Gorbet, F.M. Shokes and T.A. Kucherek, 1997. Components of resistance to early leaf spot in peanut-genetic variability and heritability. Soil Crop Sci. Soc. Fl. Proc., 56: 63-68.

Culbreath, A.K., K.L. Stevenson and T.B. Brenneman, 2002. Management of late leaf spot of peanut with benomyl and chlorothalonil: A study in preserving fungicide utility. Plant Dis., 86: 349-355.
Direct Link  |  

FAO, 2002. Crop Production Statistics. Food and Agricultural Organization, Rome, Italy.

Kannaiyan, J. and H.C. Haciwa, 1990. Economic benefits of spraying fungicides to control groundnut foliar disease in Zambia. Trop. Pest Manage., 36: 21-22.

Kemerait, R.C., T.B. Brenneman and A.K. Culbreath, 2005. Peanut Disease Control. In: Georgia Pest Management Handbook. Commercial, Guillebeau, P. (Ed.), University of Georgia Cooperative Extension Series, Athens.

McDonald, D., P. Subramanyam, R.W. Gibbons and D.H. Smith, 1985. Early and late leaf spots of groundnut. Information Bulletin No. 21. ICRISAT, Patancheru, AP 502324, pp: 19.

Naab, J.B., F.K. Tsigbey, P.V.V. Prasad, K.J. Boote, J.E. Bailey and R.L. Brandenburg, 2005. Effects of sowing date and fungicide application on yield of early and late maturing peanut cultivars grown under rainfed conditions in Ghana. Crop Prot., 24: 325-332.
CrossRef  |  

Naab, J.B., P. Singh, K.J. Boote, J.W. Jones and K.O. Marfo, 2004. Using the CROPGRO-peanut model to quantify yield gaps of peanut in the guinean savanna zone of Ghana. Agron. J., 96: 1231-1242.
Direct Link  |  

Nutsugah, S.K., C. Oti-Boateng, F.K. Tsigbey and R.L. Brandenburg, 2007. Assessment of yield losses due to early and late leaf spots of groundnut (Arachis hypogaea L.). Ghana J. Agric. Sci., 40: 21-27.
Direct Link  |  

Nutsugah, S.K., F.K. Tsigbey and K.O. Marfo, 1998. Effect of neem extract and two systemic fungicides on foliar diseases of groundnut in a savannah zone of Ghana. Inter. Arch. Newslett., 18: 44-45.

SRID (Statistics, Research and Information Directorate), 2004. Production and cropped area for major crops in Ghana-2003. Ministry of Food and Agriculture.

Shokes, F.M. and A.K. Culbreath, 1997. Early and Late Leaf Spots. In: Compendium of Peanut Diseases, Kokalis-Burelle, N., D.M. Porter, R. Rodriguez-Kabana, D.H. Smith and P. Subrahmanyam (Eds.), 2nd Edn., American Phytopathological Society, St. Paul, MN, USA., pp: 17-20.

Subramanyam, P., D.C. Greenberg, S. Savary and J.P. Bosc, 1991. Diseases of groundnut in West Africa and their management: Research priorities and strategies. Trop. Pest Manage., 37: 259-269.
CrossRef  |  Direct Link  |  

Tsigbey, F.K., J.E. Bailey and S.K. Nutsugah, 2001. Managing groundnut leaf diseases in northern Ghana with fungicides, neem seed extract and local soap. Proceedings of the American Peanut Res. Education Society, July 17-20, 2001, Oklahoma City, Oklahoma, USA., pp: 38-.

Tsigbey, F.K., R.L. Brandenburg and V.A. Clottey, 2004. Peanut production methods in Northern Ghana and some disease perspectives. World Geography of the Peanut Knowledge Base Website. http://lanra.anthro.uga.edu/peanut/knowledgebase /request.pdf, pp: 9.

Tsigbey, F.K., S.K. Nutsugah and J.E. Bailey, 2000. Evaluation of neem, soap and Topsin-M in groundnut leaf spots control in northern Ghana. Proceedings of the 6th Regional Groundnut Meeting for Western and Central Africa, October 5-8, 2000, Bamako, Mali, pp: 35-.

Waliyar, F., 1991. Evaluation of yield losses due to groundnut leaf diseases in West Africa. Proceedings of the 2nd ICRISAT Regional Groundnut Meeting for West Africa, September 11-14, 1991, Niamey, Niger. ICRISAT, Patancheru, India, pp: 32-33.

Waliyar, F., M. Adomou and A. Traore, 2000. Rational use of fungicide applications to Maximize peanut yield under foliar disease pressure in West Africa. Plant Dis., 84: 1203-1211.
Direct Link  |  

©  2019 Science Alert. All Rights Reserved
Fulltext PDF References Abstract