Research Article

Evaluation of Difenoconazole along with Macronutrients Spray for the Control of Brown Leaf Spot (Bipolaris oryzae) Disease in Rice (Oryza sativa) Crop

Muhammad Asghar1*, Mirza Muhammad Qadeer Baig1, Sanaullalh Chaudhary1 and Muhammad Anjum Ali2

1Adaptive Research Farm, Gujranwala, Pakistan; 2Directorate General Agriculture (Ext. and A.R.) Punjab, Lahore, Pakistan.

Received | October 03, 2015; Accepted | November 01, 2018; Published | January 06, 2019

*Correspondence | Muhammad Asghar, Adaptive Research Farm, Gujranwala, Pakistan; Email: miang786@yahoo.com

Citation | Asghar, M., M.M.Q. Baig, S. Chaudhary, M.F. Iqbal and M.A. Ali. 2019. Evaluation of difenoconazole along with macronutrients spray for the control of brown leaf spot (Bipolaris oryzae) disease in rice (Oryza sativa) crop. Sarhad Journal of Agriculture, 35(1): 1-6.

DOI | http://dx.doi.org/10.17582/journal.sja/2019/35.1.1.6

Keywords | Difenoconazole, Macronutrients, Brown leaf spot, Basmati rice, NPK

Introduction

Rice (Oryza sativa L.) is an important food crop in the developing countries and the staple food of more than half of the world’s population. Worldwide, more than 3.5 billion people depend on rice for more than 20% of their daily calories intake (IRRI, 2012). Besides an important exportable item, it is staple food crop of Pakistan next to wheat. It accounts for 3.2 percent value addition in agriculture and 0.7 percent of GDP of the country. During the year 2014-15 rice was cultivated on an area of 2891 thousand hectares with total production 7005 thousand tons with an average yield of 2423 kgha-1 (Anonymous, 2015). Rice yield in Pakistan is very low as compared to other rice growing countries of the world (Seebold et al., 2004).

There are number of abiotic and biotic factors responsible for reduction of per hectare yield of rice crop in the country. Amongst the biotic factors, rice diseases, especially leaf spot fungal disease caused by Bipolaris oryzae is one of the serious diseases with widespread distribution and existence of its several physiological races (Chakrabarti, 2001; Asghar et al., 2007; Arshad et al., 2008). This disease has been reported in all rice growing areas in the world and is reported to reduce 6 to 90% yield in Asia (Singh and Singh, 2000; Aryal et al., 2016). There are indications that BLS is becoming more frequent and severe due to climate change (Savary et al., 2005; Barnwal et al., 2013).

In Pakistan, BSL has been reported both on fine and coarse varieties of rice. Symptoms of BLS appear on leaves and glumes at the time of maturity of crop (Iqbal et al., 2015). Its pathogen penetrates in the rice husk causing spotting and discoloration of grains leading to reduced grain quality (Ou, 1985; Moletti et al., 1997). It also infects the coleoptile, leaves, leaf sheath, panicle, branches, glumes and spikelets (Webster and Gunnell, 1992) and causes significant yield losses. The pathogen can survive on infected rice stubbles, weeds, seeds and causes brown spot on subsequent rice crop (Ou, 1985; Moletti et al., 1996).

The high yield of rice crop can be achieved by high yielding varieties and better plant protection measures against pest and diseases (Srivastava et al., 2010). BLS can be controlled successfully through the foliar application of fungicides on rice crop (Singh et al. 1985). In the traditional rice growing area of Punjab (Pakistan), farmers mostly use difenaconazole fungicide for the control of BLS disease. Recently, the farmers reported that the spray of this fungicide alone does not provide complete or long lasting protection.

Keeping in view the devastating nature of BLS and importance of rice crop, the present study was planned to evaluate difenoconazole along with various concentrations of macronutrients to control BLS disease on rice crop and their effects on yield thereafter.

Materials and Methods

The study was designed to find the best combination of difenoconazole 250EC and various concentrations of spray able formulations of macronutrient (NPK) to control the BLS of rice in natural field conditions at Adaptive Research Farm Gujranwala, Pakistan during Kharif seasons 2012 to 2014. The nursery of rice cultivar Super Basmati was sown in the month of June. The land was prepared according to traditional agronomic practices of the area and 35 days old rice nursery was transplanted manually in well puddled soil. The plot size for each treatment was 6m×20m with plant to plant and row to row distance of 9 inches. Nitrogenous (N), phosphatic (P) and potassium (K) fertilizer was applied @ 140, 80 and 62 Kg ha-1 respectively. All P and K fertilizer was applied at the time of sowing while urea was applied in three equal splits. Weeds were controlled by Machete (butachlore) 60EC @ 2.00Lha-1whereas Cartap 4G was used as insecticides @ 22.5 Kgha-1 when the pest insects reached at Economic Threshold level (ETL). Rice crop with various combinations of difenoconazole 250EC and concentrations of macronutrients (NPK) was sprayed when the crop reached at panicle emergence stage. The experiment was replicated thrice using Randomized Complete Block Design (RCBD) Treatments comprising following combinations of difenoconazole and various concentrations of NPK were tested:

T1= (Control)

T2 = Difenoconazole @ 315 mlha-1 + NPK (20:20:20) @500gha-1

T3 = Difenoconazole @ 315 mlha-1 + NPK (8:8:6) @500gha-1

T4 = NPK (20:20:20) @500mlha-1

T5 = Difenoconazole @ 315 mlha-1

T6 = NPK (8:8:6) @500gha-1

The incidence of BLS was recorded by counting number of brown leaf spots on leaves before application of treatments and 20 days after the treatment. The intensity of disease was measured by using the scale given by Lenz et al. (2010) as shown in Figure 1. For this purpose, 30 leaves from each treatment were selected at random and brown spots on leaves were recorded. The 30 scored leaves were averaged to estimate intensity of disease. On maturity, the crop was harvested and threshed manually to record data of 1000-grains weight (g) and yield (tha-1). The benefit cost ratio on the basis of total expenditures incurred and income received was also computed. Data were subjected to analysis of variance (ANOVA) and the differences among means were compared using Duncan’s Multiple Range Test at 5% probability level (Steel et al., 1997).

Results and Discussion

The pre-treatment data given in Table 1 indicated that mean over seasons number of BLS per leaf was 7.32 to 8.75 before spray. A significant decrease in number of brown leaf spots per leaf i.e. 9.31, 11.80 and 12.69 was recorded in rice crop sprayed with T2 (difenoconazole @315 mlha-1 + NPK (20:20:20) @500gha-1), T3 (difenoconazole @ 315 mlha-1 + NPK (8:8:6) @500gha-1) and T5 (difenoconazole @ 315 mlha-1) treatments, respectively as compared to control (Table 2). However, maximum disease incidence (21.99 spots per leaf) was observed in control plot. Foliar sprays of phosphate and potassium can induce systemic protection against foliar pathogens (Reuveni and Reuveni, 1998).

Table 1: BLS per leaf on rice crop before spray of difenoconazole and macronutrients.

Nas and Fin (2012) reported that P and K are most consistent and effective in minimizing disease incidence. Though P and K application can reduce diseases and improve plant health (Perrenoud, 1990), yet disease cannot be controlled completely by the use of fertilizers alone. Mustafa et al. (2013) and Iqbal et al. (2015) reported reduction in disease incidence by the spray of difenoconazole. However, in many cases periodic applications of fungicides is suggested for economic control of diseases (Reuveni and Reuveni, 1998).

Table 2: BLS per leaf on rice crop after spray of difenoconazole and macronutrients.

Statistical analysis (P<0.05) depicted significant decrease in 1000-grain weight of rice crop not sprayed with fungicide or NPK (control). However, maximum 1000-grain weight of 22.54g and 22.09g was observed when crop was sprayed with T2 (difenoconazole @ 315 mlha-1+NPK (20:20:20) @500gha-1) and T3 (difenoconazole @ 315 mlha-1+NPK (8:8:6) @500gha-1), respectively (Table 3). Rice crop that was sprayed with T2 (difenoconazole @ 315 mlha-1+NPK (20:20:20) @ 500gha-1) attained maximum yield (3.57 tha-1) followed by T3 (difenoconazole @ 315 mlha-1+NPK (8:8:6) @500gha-1) (3.50tha-1) and T5 (difenoconazole @ 315 mlha-1) (3.46tha-1) (Table 4). However, yield was significantly reduced in control. Paddy yield was also improved after management of disease (Singh et al., 2007). According to Iqbal et al. (2015) the use of difenoconazole for the economic control of BLS of rice can be recommended. Mustafa et al. (2013) had also reported reduction in disease incidence in rice crop by the foliar application of difenoconazole which led to an increase in rice yield thereafter. Tuli et al. (2017) found that difenoconazole was effective in reducing the incidence of BLS and blast diseases at flowering, milking, dough and maturity stages of rice crop. Qudsia et al. (2017) demonstrated that six fungicides including difenoconazole control the brown leaf spot significantly as compared to Control.

Table 3: Effect of difenoconazole and macronutrients on 1000- grain weight (g) of rice crop.

Economic analysis computed on the basis of grain yield revealed that rice crop sprayed with T2 (difenoconazole @ 315 mlha-1 + NPK (20:20:20) @ 500gha-1) gave the highest additional income (Rs. 26305ha-1) followed by T3 (difenoconazole @ 315 mlha-1 + NPK (8:8:6) @ 500gha-1(Rs.22869 ha-1) and T5 (difenoconazole @ 315 mlha-1 (Rs.18323ha-1) as given in Table 5. Additional expenditure over check was the highest (Rs.2259 ha-1) in T2 (difenoconazole @ 315 mlha-1 + NPK (20:20:20) @ 500gha-1) as compared to other combinations. Maximum benefit cost ratio (11.31) was gained with T2 (difenoconazole @ 315 mlha-1 + NPK (20:20:20) @500gha-1). This highest benefit cost ratio is due to less disease incidence which ultimately resulted in high yield as compared to other treatments.

Table 4: Effect of difenoconazole and macronutrients on yield of rice crop (t ha-1).

Table 5: Economic comparison of different combinations of Difenoconazole and macronutrients.

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