Trichoderma is a well documented biocontrol agent of fungus origin being used for the control of various plant pathogens as people are being aware of the various detrimental effects of chemical pesticides. In Nepal also, the biocontrol agents are gaining popularity and there are several Trichoderma products in different trade names available in the market with label that they can be used within six months from the date of manufacture. However, it is very essential to know the fact that these microbial products contain living micro-organisms and therefore the conditions of storage for long term viability of the product should be given prior importance. This study was performed to find out the shelf life of Trichoderma viride based on various formulations and to know the effect of temperature on its viability. It was found that liquid based formulation and organic formulation had greater shelf life compared to talc based powder formulation. Also low temperature (4ºC) significantly increased the shelf life of the product (for over a year) while at ambient temperature conditions (15-25ºC), optimum viability of the biocontrol agent could be achieved only for a maximum of 3 months. Therefore it is important that farmers use fresh products and/ or store the products at cool and dark place to exploit the benefits of biopesticides.

Biocontrol is an important aspect of disease management for plant pathogens, especially for the soil borne fungi. Trichoderma species is the most exploited biocontrol agent in recent years. The soil specific nature of Trichoderma species is a well-known fact and hence native Trichoderma isolates should be more emphasized for control of plant pathogens. Fifty soil samples from rhizosphere of various agricultural crops were collected for isolation of Trichoderma sp. Ten isolates of Trichoderma were tested in dual culture with soil borne pathogens Fusarium solani, Rhizoctonia solani and Sclerotinia sclerotiorum in an in vitro assay. All of the test isolates were found to be significant in terms of mycelial inhibition growth as compared to control. However, varying degrees of antagonism by different Trichoderma isolates were observed for above mentioned soil borne pathogens. The isolate (T363) was found to exhibit more than 80% inhibition of S. sclerotiorum while the isolate T357 was found to control F. solani by more than 80%.  For the control of R. solani, six of the tested Trichoderma isolates showed more than 80% inhibition of its radial colony growth. The Trichoderma isolates seen effective in this study need to be tested in pot and field experiments for exploiting the use and benefits of biocontrol.

Fusarium wilt of banana (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), is the most important constraint of the banana industry globally. In Nepal, epidemics resembling FWB have been increasingly observed on the Malbhog cultivar in the past several years. However, the disease has not been officially reported yet, and consequently, little is known about the pathogen present across the country. In this study, we characterized 13 fungal strains isolated from banana plants of the Malbhog cultivar (Silk, AAB) showing symptoms similar to FWB in banana plantations in Nepal. All of the strains were typed as belonging to the F. oxysporum and caused FWB symptoms when inoculated in the Malbhog and Cachaco (Bluggoe, ABB) cultivars. No symptoms were observed in the Williams cultivar (Cavendish, AAA). Vegetative compatibility group (VCG) analysis classified the strains as VCG 0124 or VCG 0125. PCR analyses conducted with primers specific for Foc race 1 (Foc R1) or Foc tropical race 4 (TR4) revealed that all the strains reacted positively for Foc R1 and none for TR4. Altogether, our results demonstrated that the pathogen populations causing FWB of the Malbhog cultivar in Nepal were Foc R1. This work reported, for the first time, the occurrence of FWB in Nepal. Further studies with larger Foc populations are needed to better understand disease epidemiology to design sustainable disease management strategies.

Diseases are one of the major constraints on cultivation of crops and reduce production and productivity. Accurate disease diagnosis and proper identification is the first steps of disease management strategy. The activities of carrying out disease diagnosis help to know the distribution of the diseases in the country, explore new disease outbreak and its epidemiology, and provide information for disease management and support in research area prioritization. During fiscal year 2070/71, 252 different disease samples of different vegetable crops were received from various locations and sources for disease diagnosis. Examination of such samples identified 192 samples with fungal infection, 23 with bacterial infection, 28 with viral infection and 9 with nematode infection. In solanaceous crops, 70% disease caused by fungus and 11% by bacteria, 14% by virus and 5% by nematodes respectively. Likewise, in cucurbit crops, occurrence of pathogens is 61% fungal, 26% viral and 13% nematode respectively. The fugal pathogens were dominant in case of crucifer crops as well. The fungal pathogens were found in 79% of samples and followed by bacterial in 14% and viral in 7% respectively. Only fungal pathogen was detected in bulb and root crops. Fungal pathogens (76%) are the common problem in vegetable crops by followed by bacteria (9%) and virus pathogens (11%) and nematode (4%). The study revealed that management of fungal disease is prime concern to minimize the losses due to disease.