Evaluating the Effectiveness of Various Fungitoxicants and Botanical Extracts against Alternaria Leaf Blight in Faba bean (Vicia faba), Caused by Alternaria alternata in In-vivo Condition

The faba bean, scientifically called Vicia faba, is among the earliest domesticated dietary legumes (Sahile et al., 2011). It is frequently known by different names, including tic bean, horse bean, field bean, broad bean, and fava bean. The crops are considered highly significant from a scientific perspective due to their rich nutritional composition and their role in improving soil health through biological nitrogen fixation and organic matter enhancement (Bhardwaj et al., 2024). The Neolithic era is thought to have been when it was domesticated (Metayer, 2004). It is extensively cultivated in Asia and Africa (Soysal, 2021). Although it may also be effectively produced in hilly and mountainous places during the kharif season, the faba bean is mostly farmed in India’s plains as a rabi pulse (Singh and Bhatt, 2012b). Another common garden produce is faba beans. They are the fourth most significant food legume in the world, after garden peas (Valente et al., 2018).  Furthermore, faba beans are a great option for crop rotation with cereals and other plants since they fix nitrogen, which is essential for increasing soil fertility (Al-Abdalall, 2010; Teshome and Tagegn, 2013). Several scientific studies have demonstrated that the cultivation of crops following faba bean can lead to substantial reductions in nitrogen fertilizer requirements ranging from 100 to 200 kg N/ha without compromising maximum yield (Adak and Mehmet Kibritci, 2016). North Africa and Southwest Asia are the native habitats of the faba bean.  According to Alshameri et al., (2021) and Crépon et al., (2010), the protein content of faba beans ranges from 24 to 35%. Faba beans are vital contributors to global food security and provide essential nutrients to human and livestock diets (Jeong and Na, 2024). They are an excellent complement to a balanced diet because they are also a great source of vitamins, minerals, and dietary fibre (Ouraji et al., 2020; Xiao et al., 2021; Rosa-Sibakov et al., 2018). Fresh or dried, faba beans can be used to make flour, hummus, and falafel, among other things. They can be used in salads, soups, stews, and side dishes due to their versatility in the kitchen (Zhang et al., 2020).
               
Following the common bean, pea, chickpea, cowpea and lentil in terms of total production, faba beans came in sixth place worldwide in 2018-19 with 4.5 million tons produced from 2.5 million hectares. China is the world’s largest producer and planter of faba beans (Khazaei and Vandenberg, 2020). Since faba beans are a traditional legume crop in Bihar, the state possesses the biggest area in India allocated to their cultivation. Madhya Pradesh, Odisha, Jharkhand and Uttar Pradesh are other Indian states that cultivate faba beans, especially in the eastern part of the country (Singh et al., 2012a).  Influences including disease outbreaks and climate change have caused changes in recent production patterns (Mínguez and Rubiales, 2021). Numerous biotic and abiotic stresses have an effect on faba beans, resulting in a considerable decrease in their total yields (El-Hendawy et al., 2010). Numerous harmful viruses and pathogens target the crop, particularly in the Mediterranean region. Regarding faba beans, fungi are one of the most prevalent and possibly dangerous groups (Honda et al., 2001; Reis et al., 2007; Juroszek and von Tiedemann, 2011). Faba beans are vulnerable to a variety of illnesses brought on by bacteria, nematodes, viruses and fungi, just like other pulse crops.  The fungus Alternaria alternata is the main cause of Alternaria leaf spot, one of the fungal diseases that poses a serious risk to faba beans. This disease is marked by the development of dark, necrotic lesions on the leaves, which can significantly reduce yield by impairing photosynthesis and causing early leaf drop (Kamble et al., 2000; El-Metwally et al., 2010). It is particularly harmful in humid regions, where the environmental conditions are conductive to the growth of the pathogen (Abdel, 2008).

Study area
 
The present investigation entitled “Evaluating the effectiveness of various fungitoxicants and botanical extracts against Alternaria leaf blight in faba bean (Vicia faba), caused by Alternaria alternata in in-vivo condition” was carried out in the Department of Plant Pathology’s laboratory and performed in the field at the Genetics and Plant Breeding Farm, which is a part of the Department of Plant Pathology, College of Agriculture ANDUAT, Ayodhya (U.P.) during 2022-25.
 
Efficacy of fungi-toxicants against the pathogen in in vivo for the control of the disease
 
To find out the efficacy of thirteen fungi-toxicant including fungicides and botanicals (T₁-Seed treatment with azoxystrobin @ 10 ml/kg seed, T₂-Chlorothalonil 75 WP @ 0.15% spray, T₃-NSKE @ 5% spray, T₄-NSKE @ 10% spray, T₅-Garlic extract 5% spray, T₆-Garlic extract 10% spray, T₇-Seed treatment with azoxystrobin @ 10 ml/kg seed + Chlorothalonil 75 WP 0.15% spray, T₈-Seed treatment with azoxystrobin @ 10 ml/kg seed + NSKE @ 5% spray, T₉-Seed treatment with azoxystrobin @ 10 ml/kg seed + NSKE @ 10% spray, T₁₀-Seed Treatment with Azoxystrobin @ 10 ml/kg seed + Garlic Extract 5% spray, T₁₁-Seed treatment with azoxystrobin @ 10 ml/kg seed + Garlic extract 10% spray,  T₁₂- Carbendazim 12% + Mancozeb 63% WP and T₁₃-Untreated control) were tested in vivo condition against the pathogen.

For botanical testing, fresh parts of the test plants were collected and washed thoroughly in tap water. 50 g of each sample were grinded in mortar and pestle by adding 500 ml of sterilized water (1:1 w/v) and boiled them at 80^oC for 10 minutes in water bath. The grinded material was filtered through muslin cloth followed by filtering through sterilized Whatman No 1 filter paper and treated as standard plant extract (100 per cent) (Bhat and Sivaprakasan, 1994).
 
Effectiveness of various fungitoxicants and botanical extracts
 
The present investigation aimed to assess the effectiveness of different fungitoxicants and botanical formulations against Alternaria leaf blight of faba bean, incited by Alternaria alternata, under in vivo conditions using the susceptible genotype ‘Vikram’. All evaluated treatments, including fungicides and botanicals, exhibited varying levels of efficacy in managing the disease.
       
A susceptible faba bean germplasm (Vikram) was sown on 2^nd week of November, 2022-2025. Efficacy of fungicides along with botanicals were evaluated against Alternaria leaf blight of faba bean by spraying on naturally infected plants.


       
After attaining the age of 60 days, the plants were inoculated with mycelium cum spore suspension of the pathogen and the field was irrigated from time to time to maintain proper humidity. The first spraying of fungi-toxicant using recommended doses was given 72 hours after inoculation followed by two more applications at an interval of 10 days. The plots of faba bean plants, sprayed with water served as control. Final observations on percent disease intensity (PDI) were recorded 15 days after the last spraying on the basis of percentage leaf area affected. The yields of leaves per plot were also recorded after harvest of the crop. The percentages of disease controls over check were calculated by the fallowing formula (McKinney, 1923).

Rating scale 0-9 (Mayee and Datar, 1986) for Alternaria leaf blight disease.
 
Statistical analysis
 
The data of the experiments conducted in fields was subjected to statistical analysis. The critical differences were worked out at 5% probability level to find the difference between the treatments. The data were transformed whenever required.

Effect of fungitoxicants against alternaria leaf blight of during 2022-23 to 2024-25
 
A field study conducted from 2022 to 2025 to assess the effectiveness of various fungi-toxicants and bio-extracts in managing Alternaria leaf blight of faba bean, caused by Alternaria alternata. The treatments were evaluated based on per cent disease index (PDI), per cent disease control (PDC), total yield (q/ha), percentage yield increase, test weight (g) and percentage increase in test weight. The results indicated considerable variation among treatments in their ability to control disease and improve yield-related traits (Table 1).
 


Disease management (PDI and PDC)
 
The data revealed that seed treatment with Azoxystrobin + Chlorothalonil 75 WP was the most effective, showing the lowest PDI of 12.45% and the highest PDC of 74.08%, significantly outperforming all other treatments. This was followed closely by Carbendazim 12% + Mancozeb 63% WP (PDI: 13.94%, PDC: 71.28%) and seed treatment with azoxystrobin + Garlic extract 10% (PDI: 17.22%, PDC: 64.00%). In contrast, the untreated control plot recorded the highest PDI of 47.06%, with no disease control, indicating the high susceptibility of faba bean to Alternaria leaf blight under unmanaged conditions (Table 2).


 
Effect on yield and yield components
 
The disease control achieved through effective treatments translated into improved yield performance. The highest yield (24.23 q/ha) was recorded in plots treated with Azoxystrobin + Chlorothalonil, with a yield increase of 24.91% over the untreated control. This was closely followed by Carbendazim + Mancozeb (24.03 q/ha, 23.89% increase) and Azoxystrobin + Garlic Extract 10% (23.42 q/ha, 20.72% increase). On the other hand, NSKE 5% recorded the lowest yield (20.63 q/ha) among treatments, with only a 6.36% increase over the control, highlighting its relatively lower efficacy (Table 2).
 
Test weight and seed quality
 
The highest test weight (91.73 g) was also achieved with the Azoxystrobin + Chlorothalonil combination, with a 14.31% increase over the control (80.25 g). Similarly, Carbendazim + Mancozeb (90.53 gm) and Azoxystrobin + Garlic Extract 10% (89.72 g) significantly improved test weight, indicating better seed quality associated with effective disease management (Table 2).
 
Statistical significance
 
The differences among treatments were statistically significant as indicated by the C.D. at 5% for PDI (3.07), PDC (5.88) and total yield (1.90 q/ha). The coefficient of variation (C.V.) for yield parameters was within acceptable ranges (5.05% for total yield and 5.92% for test weight), ensuring data reliability. However, higher C.V. for test weight increase (71.48%) reflects variability in seed development due to environmental or biological factors (Table 2).
 
Integrated management approach
 
The findings clearly underscore the superiority of integrated treatment approaches especially those combining seed treatment with Azoxystrobin and foliar application of Chlorothalonil or botanical extracts in enhancing both disease resistance and crop productivity. Notably, these combinations were more effective than individual treatments, suggesting a synergistic effect.
               
Evaluation of the efficacy of different fungitoxicants and botanical extracts against Alternaria leaf blight of faba bean (Vicia faba), caused by Alternaria alternata, under in vivo conditions. Some related findings were reported in other crops by scientists and other workers such as Sharma et al., (2022), Choudhary et al., (2020), Kokare et al., (2020), Jackson and Kumar, (2019), Rani et al., (2018) and Zade et al., (2018).

The pooled data from 2022 to 2025 demonstrated that the integrated application of Azoxystrobin seed treatment combined with Chlorothalonil 75 WP foliar spray was the most effective strategy for managing Alternaria leaf blight in faba bean. This treatment recorded the lowest Percent Disease Index (12.45%), highest disease control (74.08%) and resulted in the highest yield (24.23 q/ha) and test weight (91.73 g). Chemical treatments such as Carbendazim + Mancozeb and combinations with botanical extracts like Garlic and NSKE also showed promising results, particularly when used in combination with Azoxystrobin. Individual botanical treatments, while less effective on their own, provided moderate disease control and yield benefits. The untreated control recorded the highest disease incidence (47.06%), lowest yield (19.40 q/ha) and lowest seed weight (80.25 g), reinforcing the importance of effective disease management. Overall, the study concludes that integrated disease management especially combining systemic fungicide seed treatment with effective foliar sprays significantly improves disease suppression, yield and seed quality in faba bean crops.

My adviser and vice-chancellor of the Acharya Narendra Deva University of Agriculture and Technology, located in Kumarganj, Ayodhya, India, provided the facilities required to perform the research for this work.
 
Disclaimers
 
Only the authors’ opinions and conclusions are presented in this article and they may not be representative of those of their connected institutions. The writers disclaim any liability for any direct or indirect losses coming from the use of this content, however they are accountable for the completeness and accuracy of the information supplied.
 
Informed consent
 
The ANDUAT, Ayodhya of Animal Care Committee authorized the handling methods and all experimental procedures were approved by the Committee of Experimental Animal Care.

In relation to the publishing of this work, the authors declare that they have no conflicts of interest. The study design, data collection, analysis, publication decision and manuscript preparation were all independent of funding or support.