Evaluation of certain fungicides against Alternaria sesame causing leaf spot disease in Sesame, (Sesamum indicum L.) under In-Vitro and In-Vivo conditions

Introduction

Sesame, (Sesamum indicum L.), is one of the world's ancient important oilseed crop cultivated in more than 55 countries of the world belonging to the family Pedaliaceae and native of India. It is an herbaceous, annual, self-pollinated (considerable insect cross pollination) crop with 2n=26 chromosomes and which is mentioned in Atharva Veda, Ashtadavaiji, Manusmriti and Puranas as tila indicating the presence of sesame in India since the pre-christian era. The mesopotamian ellu seems to be connected with the Dravidian word and crop ellu from the Indian sub-continent. Genetic, morphological and phytochemical evidences support the hypothesis that domesticated sesame had originated on the Indian subcontinent (Bedigian and Harlan, 1986) [1] . The Portuguese introduced sesame to Brazil where it is known as gangelim, a name is as directly comparable with the Indian name gingelly as to suggest that it was from their Indian colonies. About 78 percent of sesame produced in India is used for oil extraction. India export sizeable quantity of sesame seeds to different countries. Sesame oil is used for edible purpose besides; it is widely used in the manufacture of soaps, scented hair oils, cosmetics, insecticides, perfumes, paints and in pharmaceutical products. Seeds are directly used in different foods and also as a flavouring agent. In certain parts of India, such as Andhra Pradesh, Ghani press cake from dehulled seed is used as an ingredient for curry preparations. The hull accounts for 15-20% of the whole seed and contains 2-3% oxalic acid and 1-2% calciumand is high in fibre. A hundred gram of seeds provides 502 calories. Sesame oil is important cooking oil in the south India. It is really the poor man's substitute for ghee. Powdered sesame seeds with rice and honey are used to prepare funeral cakes called Pindas. The oilcake is an edible cake. It is eaten mixed with sugar by poor people. It is also used as a livestock feed especially for Milch animals and poultry because of rich in protein, vitamin (Niacin), minerals (Ca and P) and methionine content. Sesame cake is also used as soil amendment for control of various diseases (Maiti et al.,, 1985) [8] . In India, sesame crop is commonly grown in Kharif season, also grown as pre-Kharif and summer crop. Sesame is basically a quantitative short day plant and with a 10 hour day period normally flowers in 40-50 days. Temperature range for optimum from seedling emergence to flowering and fruiting has been found to be in the range 27-33⁰ C. A temperature of 40⁰ C or above at flowering can seriously affect fertilization and number of capsule set. A frost free growing period is required for sesame; hard frost at maturity will not only kill plants but will also reduce seed and oil quality. It can also adversely affect minor seed oil constituents such as sesamolin and sesamin. The area, production and productivity of sesame has been reported to be 13.05 and 15.31 lakh hectares, 6.8 million tonnes and 8.74 lakh tonnes, 520 kg/ha. And 571 kg/ha. During 2023 respectively, in the World and India. Major sesame growing states in India are: West Bangal (33%), Gujarat (17%), Madhya Pradesh (14%), Uttar Pradesh (14%), Rajsthan (9%). However, crop is grown in all the states of country. The total area in Uttar Pradesh under sesame was 3.03 lakh hectares area, with production 0.08 metric tons and productivity of 239 kg/ha (Department of Agriculture and Farmers Welfare 2023-24). Sesame is called as -Queenl of oilseeds in view of its high quality edible oil (38 to 54%) and proteins 18 to 25%. Among the major factors responsible for lower yields, diseases play an important role. Sesame is also affected by many biotic and abiotic stresses. Among the biotic agents, fungi cause major diseases, followed by Bacteria, Viruses and Nematodes. Major Sesame diseases caused by fungi Viz. [3] . Among these diseases, at present leaf spot/blight caused by Alternaria sesami (Kawamura) is widespread and have continued to be the major constraints in the production and productivity of sesame all over the country in general as well as in the state of Uttar Pradesh particularly. The Alternaria leaf blight disease was first reported by Dey (1948) [6] from Uttar Pradesh, which later spread in sesame growing region of the country (Dolle, 1981; Kolte, 1985; Narute and Utikar, 1994) [4,11,12] . The disease has been reported to cause 20 to 40 per cent yield losses all over India. The pathogen being seed borne, initially dark necrotic lesions (2-5 mm) appear on the hypocotyls as well as cotyledons. The initial symptoms of leaf blight of sesame incited by A. sesami appears right from seedling stage (30 days old) as small isolated light brown to dark brown circular spots (1-2 mm) on leaves mostly marginal and apical. As the infection progress, these spots enlarge and become irregular. In the centre of the spots, there appears a brown dot surrounded by a number of alternating dark concentric rings, later lesions coalesce to form large patches covering greater area of leaves, resulting in defoliation in severe cases. The symptoms also appear on stem, petiole and pods. Infection on stem covered majority area and produced browning and blighting of stem, while on pods deep seated spots damage the seed quality and caused heavy loss of seed yield. methyl, Chlorothalonil and Captan+Hexaconazole were used as spray for recording the disease incidence in percentage was transfer into angles and analysed statistically. Yield was estimated a plot basis without the border row in the q/ha. Disease incidence was calculated using following formula

Materials and Methods

Efficacy of fungicides against

The experimental details was as for given below:-Experimental details: (In-Vivo) •Replication: 3

Result and Discussion

Efficacy of fungicides against Alternaria sesami under In-Vitro condition Seven fungicide were tested according to the procedure mentioned under "Materials and Method" Growth of the pathogen was observed and average diameter of colony in each Petri dish was recorded. Percent over inhibition over control was calculated separately for each treatment and presented in Table 1.

The result presented in Table 1. and corresponding histogram Fig. 1 during year 2023-2024 showed that all the fungicide tested were significantly superior to the control in inhibiting the growth of the pathogen. The tested fungicide Carbendazim+Mancozeb and Mancozeb proved to be the most effective fungicide as they showed (0.00cm) fungal growth and complete inhibition of the fungal growth (100%). Thiophanate methyl and Chlorothalonil were the next best effective fungicide which recorded the growth of 2.53cm and 2.83cm, respectively, and their percent inhibition of the fungal growth compared to our control were 43.77% and 37.11%, respectively. Both were statisticaly at par with each-other. Captan+Hexaconazole and Propineb were the next good effective fungicide which recorded the growth of 3.43cm and 4.10cm, respectively, and their percent inhibition over control were 23.77% and 8.88%. The least effective fungicide was Metalaxyl, which showed the maximum average fungal growth (4.20cm) and minimum inhibition (6.66%) over control. The similar result was also observd by Meena et. al., (2013) [9] .

The result presented in Table 1. Plate 2. And corresponding histogram Fig. 1 during year 2024-2025 showed that all the fungicide tested were significantly superior to the control in inhibiting the growth of the pathogen. The tested fungicide Carbendazim+Mancozeb and Mancozeb proved to be the most effective fungicide as they showed (0.00cm) fungal growth and complete inhibition of the fungal growth (100%). Thiophanate methyl and Chlorothalonil were the next best effective fungicide which recorded the growth of 2.50cm and 2.70cm, respectively, and their percent inhibition of the fungal growth compared to our control were 58.33% and 55.00%, respectively. Both were statisticaly at par with each-other. Captan+Hexaconazole and Propineb were the next good effective fungicide which

References

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