Evaluation of some fungicides for Management of Sugar cane rust (Puccinia melanocephela) disease in Finchaa Sugar Estate, Horo -Guduru Wollega, Oromia Regional State, Ethiopia

Sugarcane (Saccharum offi cinarum L.) is an important industrial, monocotyledonous perennial cash crop. Sugarcane brown rust (Puccinia melanocephela Syd. & P. Syd) is one of the most devastating diseases. Sugar cane brown rust is new for Ethiopia and currently only fi ncha sugar Estate is affected. The current study was carried out to evaluate the effi ciency of different fungicides (Opera, Tilt, Natura, Defender, Diprocon and Noble) with three times spray frequencies and their impact on yield and yield components under fi eld conditions in Finchaa Sugar Estate, Ethiopia, during the main cropping season of 2016. For the management of sugarcane brown rust disease, seven treatments were arranged in randomized complete block design with three replications on sugarcane cultivated fi elds at Finchaa Sugar Estate. The statistical analysis showed that signifi cant differences among treatments in sugarcane brown rust disease incidence, severity. Sugarcane brown rust incidence and severity were highest in the control plots compared to the fungicides sprayed plots. The highest severity value resulted in the lowest cane yield of sugarcane 26.26 t/ha in the control plots compared to a highest yield of 78.27 t/ha from sprayed plots with Opera fungicide and 64.9 t/ha from plots treated with Natura fungicide . Economic analysis revealed that the highest rate of return of 5751 birr was obtained from fungicide Opera and the highest net benefi t 55559 birr again from Opera foliar spray treatment. The results of the present study revealed that the novel possibility of using foliar spray treatments which was found to be effective in decreasing sugarcane brown rust symptoms in sugarcane plants in Finchaa Sugar Estate and also increased yield. Further, the effective and feasible management options need to be developed on sugarcane brown rust disease in the country. Research Article Evaluation of some fungicides for Management of Sugar cane rust (Puccinia melanocephela) disease in Finchaa Sugar Estate, Horo -Guduru Wollega, Oromia Regional State, Ethiopia


Introduction
Sugarcane (Saccharum offi cinarum L.) is an important cash crop of the globe, which belongs to the grass family, Poaceae [1]. Currently, the crop is cultivated over 120 countries with estimated total annual global sugar production of 1.7 billion tons in the year 2012 [2]. Sugarcane is responsible for ~70% raw table sugar production worldwide (Contreras et al., 2009).
The sugar factories are also expected to contribute about 448 megawatt electric power through co-generation (Ethiopian Sugar Corporation [3].
In Ethiopia, sugarcane is the sole base material for sugar production and thus the sugar industries in Ethiopia depend on the fate of this crop. Sugarcane cultivation by smallholder subsistence farmers started centuries ago and preceded the commercial sector in Ethiopia [4]. A report by the Central Statistics Agency [5]  land. In Ethiopia, sugarcane is grown in some parts even before the commencement of large-scale commercial plantations and establishment of a modern sugar factory at Wonji [6].
The sugar industry in Ethiopia has great contributions to the socio-economy of the country, given its agricultural and industrial investments, foreign exchange earnings, its high employment, and its linkages with major suppliers, support industries and customers (Khan et al., 2004). However, the current sugar production in Ethiopia covers only 60% of the annual demand for domestic consumption, while the defi cit is imported from abroad.
In spite of this fact, the country has huge production potentials and opportunities, which include specifi cally identifi ed irrigable suitable fertile areas of favorable weather conditions, cheap and productive labor force, high demand for sugar and other by-products and huge market outlets to the nearby countries. The country's annual production of sugar from the sugar estates is about 400,000 metric tons (ESC 2015/16) and Finchaa Sugar Factory has a total capacity of producing 850,000 quintals of sugar in one production year (242 days).
Despite the importance of sugarcane in the country, the yield of sugarcane is constrained by many environmental and management factors [7] and its production entails an integration of various factors such as weather, water, biotic, soil and economic factors. Diseases, weeds, and insect pests are among the major biotic constraints of sugarcane production [8]. in Ethiopian Sugarcane Research Services Station [9].
The above-mentioned sugarcane rust control methods have their own gaps, for example, rusts can be managed by planting resistant cultivars. However, due to the emergence of new races of the rust fungi, the resistance present in current cultivars can be broken. Therefore, this method needs the diversifi cation of the varieties not to break their resistance. In Ethiopia, there are no chemicals evaluated to control sugarcane rust disease. Therefore, the current study was carried out to evaluate some fungicides for the management of sugarcane brown rust disease in Finchaa Sugar Estate, Ethiopia.
This study was carried out with the following objectives:  To assess the cost-benefi t ratio of fungicides with yield and yield components of sugarcane.

Description of the study area
Finchaa Sugar Estate is the third pioneer sugarcane plantation established in 1998. Finchaa Sugar Estate is located in the Finchaa River Valley of Ethiopia at a latitude of 8º31'N and longitude of 39º12'E, respectively with elevation ranging from 1350-1650 m. a. s. l. The zone has a bimodal rainfall distribution and is a typical sub-humid, high altitude agroclimatic zone. The area has a mean maximum temperature of 31 0 C and a mean minimum temperature of 15 0 C. The area has a mean annual total rainfall of 1300 mm ( Figure 1).    (Table 1). All the fungicides were registered in Ethiopia but not for sugarcane, it is for other cereal crops. The fungicide, Tilt was used as a standard control check.

Experimental design, treatments and applications
The fi eld experiment was conducted for the evaluation of fungicides for the maagement of sugarcane brown rust disesae in 2016 main cropping season at Finchaa sugar Estate sugarcane fi elds. A crop of fi ve months old with natural brown rust infection which was at tillering growth stage was selected.
Total of seven (7) treatments were evaluated ( Table 2). Six fungicides were evaluated and unsprayed plots were used as control ( Table 2). The fungicide, Tilt was used as a standard check. The experimental plots which had eight rows and each row had ten meters and the spacing between each row was 1.45mand the area of each plot was 116m 2 . The experiment was conducted using Randomized Complete Block Design (RCBD) with three replications of each treatment).All recommended agronomic practices were followed uniformly for all treatments.
Weeding was performed twice, after six months.

Growth parameters
The growth parameters such as stalk population, stalk height measurement, malleable cane count, and stalk diameter and stalk weight measurement were taken with the predetermined interval except stalk weight measurement and stalk diameter which were measured at the end date of data collection.

Sugarcane stalk population
Stalks on the whole plots were counted at monthly interval until the maturity of the crop and the mean value of the stalks were calculated and converted to hectare.

Sugarcane stalk height measurement
Plant height is a main parameter of growth and yield.
Although an internodes property (length, thickness and shape) is varietal characters, yet the rate of elongation and length of the internodes and hence plant height provides information about the general condition of the crop. Stalk height was measured from the fi rst node to the top most developed node and then averaged taking ten representative stalks from each plot.

Stalk diameter
Stalk diameter is one of major components of growth parameter for sugarcane plant. Ten sugarcane stalks were sampled out from the middle four rows of the plot to measure the diameter of the stalks.

Juice quality
Ten millable stalks were sampled from each plot at age of twelve months from the middle four furrows for juice quality determination (pol percent, purity %, sucrose% and Brix (%).   It was assumed that, the sugar Estate produce these varieties using fungicide managements when the varieties provide 100% marginal rate of returns.

Data analysis
Data on sugarcane rust disease incidence, prevalence, severity, AUDPC, disease progress rate, stalk height, millable cane, juice quality determinants (pol, cane degree Brix and purity)and cost-benefi t were subjected to analysis of variance (ANOVA) to determine the treatment effect on dependable variables using SAS statistical software package (SAS, 2003).
Least signifi cant difference (LSD) was used for mean separation. Zimbabwe, trials included the use of Triazole fungicide and found to signifi cantly reduce brown rust infections [11]. Trials in South Africa involved the use of Propiconazole (Triazole).

Sugarcane brown rust disease Severity
In the plots of the experiment after fi rst time of fungicides application there were a signifi cant difference among the plots where sugarcane brown rust disease severity occurred at P≤0.05.However, the highest sugarcane rust disease severity were recorded on the UN treated plot (fungicides UN treated plot) with sugarcane brown rust severity of about 17.00%.
Followed by plot treated with Defender with sugarcane brown rust severity of 16.0% Table 3.

Growth parameters Measurements (Stalk diameter, internodes length and stalk height)
The treatments showed a non-signifi cant difference in stalk diameter (Table 4-6). However, the average, stalk diameter (2.51cm) of the treated plots were better than that of the untreated control plots with diameter of (2.06cm). The general reduction in plant size was observed in the sugarcane rust noted plots. However, the stalk diameter on these plots was not signifi cantly different relative to the rust free plots.
Reduction in plant size is among the symptoms of rust infection in sugarcane [12][13][14][15]. The stalk height showed a signifi cant difference among the treatments (Table 6). Among the treated plots, plot receiving fungicide Opera had the highest stalk height, followed by plot receiving fungicide Tilt while the untreated control plot had the lowest stalk height Tables 7-9 [15-21].  Values having the same letters in the table are not signifi cantly different from each other at LSD (p<0.05).The above data were taken at the different times on different age of sugarcane based on the interval before and after application of fungicides

Summary and conclusions
Ethiopia has a suitable area of land for the production of sugarcane and planned to be one of the major producers of sugarcane. The low productivity of the crop in the country is attributed to susceptibility to biotic and a biotic stresses. The present study was carried out to evaluate the effi cacy of some fungicides.

Recommendations
From this study, the fungicides Opera, Natura, and Diprocon with three times spray frequencies could be recommended for the management of sugarcane brown rust disease at Finchaa sugar Estate, Horo-guduru Wollega Zone Oromia Regional Estate, Ethiopia.

Sugarcane brown rust disease was reported in March 2007
to the country, its spreads at alarming rate in most of the major sugarcane growing areas of the country.