Preservation and long-term storage of Trichoderma spp. by sodium alginate encapsulation

Trichoderma species have become popular as biocontrol agents and are being used to protect crops from many plant pathogens world over. The experiments carried out to preserve Trichoderma species in the form of sodium alginate encapsulated beads revealed that the conidial and mycelial stages in encapsulated form remained viable for more than six years at room temperature. Production of alginate encapsulated Trichoderma was relatively a simple procedure but found to be an efficient method for maintaining the pure culture and also for long-term preservation. The survival and conidiation from the encapsulated beads are very much comparable to freshly inoculated culture. The organism can be revived from encapsulated beads by inoculating onto either PDA or organic substrates like vermicompost. On revival, its bio-efficacy remained as in fresh culture, and on soil application the antagonistic potential was sheltered

Infectivity and management of dry rot, eye rot and soft rot of ginger (Zingiber officinale Rosc.)

Dry rot and eye rot of ginger are post-harvest infections noticed as caused by Macrophomina phaseolina and Fusarium oxysporum, respectively. To investigate whether these pathogens cause damage to the crop only during the cropping period and then remain latent, or are purely post-harvest in nature, an experiment was undertaken by artificially inoculating the pathogens and comparing them with soft rot caused by Pythium myriotylum. The results of the study indicate that M. phaseolina could infect ginger plants during the cropping period and cause rhizome infection, manifested as yellowing of the pseudostem and the pathogen reside inside the rhizome and develop latent infection as dry rot during storage. The pathogen could be re-isolated and proved Koch’s postulates. However, none of the Fusarium challenged plants showed symptoms either manifested as yellowing or rotting of the pseudostem. In Macrophomina-challenged plants, the infection appeared only during the post-monsoon period that coincides with the yellowing of the leaves during maturity. This observation was supported by the occurrence of natural infection by Macrophomina in harvested fresh rhizomes during 2018 and manifested as scattered elongated streaks with black mycelia inside the rhizomes, which extended from the cut end to the tip. But Pythium inoculated plants succumbed to infection as rotting of the basal portion of the pseudostem and yellowing of the lower leaves. The intensity of infection varied from 0-63 per cent. In vitro testing of seven fungicides in four different concentrations showed that metalaxyl-Mz, copper oxychloride (COC), and mancozeb even at 500 ppm are not inhibitory to M. phaseolina. But carbendazim and carbendazim-mancozeb were highly effective, giving complete inhibition even at 50 ppm. In the case of P. myriotylum, metalaxyl-Mz, COC, and Bordeaux mixture showed >70 per cent inhibition at 500 ppm. Mancozeb alone at 500 ppm was not effective against Pythium. In planta evaluation was done with fungicides individually and in combinations along with a systemic insecticide, dimethoate. Most of these treatments resulted in reduction of Macrophomina infection, of which metalaxyl-Mz alone or in combination with carbendazim (0.2%) and dimethoate (0.05%) showed 100 per cent reduction in infection. Metalaxyl-Mz (0.125%) with dimethoate (0.05%) was highly effective in reducing the infection caused by P. myriotylum

Documentation of fungal endophytes of black pepper (Piper nigrum L.) and their seed transmission studies

The present study envisaged to document the endophytic fungal association with black pepper through a series of in vitro and in planta investigations. Black pepper was found to harbour endophytic fungal flora belonging to the genera Alternaria, Acremonium, Aspergillus, Cladosporium, Chaetomium, Curvularia, Colletotrichum, Fusarium, Humicola, Paecilomyces, Rhizoctonia, Phoma and non-sporulating forms. Further, it was found that the endocarp of black pepper seed is free from culturable endophytic fungi. This was evident from the absence of culturable fungi in in vitro grown black pepper seedlings. The growth of fungi from the seedlings grown under green house conditions reveal that the fungal endophytes establish from fungal propagules falling on the (test) plants that may enter the plant tissues as back ground inoculum and grow as endophyte. This was also supported by the study that the type of endophytic fungi that harbour black pepper plants varied with geographical locations from where the samples were collected

Virulence of Phytophthora isolates from Piper nigrum L. and their sensitivity to metalaxyl-mancozeb

Foot rot disease caused by Phytophthora capsici in black pepper is the most destructive disease. A total of 82 isolates from the National Repository of Phytophthora at ICAR-Indian Institute of Spices Research were evaluated for their sensitivity to metalaxylmancozeb and also tested for their virulence. Of the 82 isolates studied, 19 (23.2%) were highly sensitive to metalaxyl-mancozeb and six (7.3%) were comparatively insensitive (EC90 value >40 ppm; range 41.3 to 68.5 ppm). The isolates also varied in the degree of virulence, viz., 34 (41.5%) were highly virulent, 39 (47.6%) moderately virulent, 4 (3.7%) mildly virulent, and 5 (6.1%) non-virulent. There was neither any significant correlation between sensitivity to metalaxyl-mancozeb and virulence nor with the geographical location.Â

Sclerotium rot - a new disease of vanilla (Vanilla planifolia Andrews) in India

A new type of bean rot affecting vanilla beans was observed in vanilla (Vanilla planifolia) growing tracts of Moovattupuzha in Emakulam District (Kerala, India). The disease was characterized by rotting of bean bunches and subsequent development of thick fungal mat over the bean surface. The causal organism was identified as Sclerotium rolfsii; the fungus was brought into pure culture and its pathogenicity was proved. This is the first report of the fungus on vanilla from India. &nbsp

Fungal and bacterial diseases of cardamom (Elettaria cardamomum Maton) and their management

Small cardamom (Elettaria cardamomum) is susceptible to a number of diseases due to fungi, bacteria and viruses. Twenty six different types of diseases have been reported of which only a few have been considered as major causing severe crop losses. The major diseases of fungal origin are 'azhukal' (capsule rot) caused by Phytophthora meadii, rhizome rot (clump rot) and seedling rot (damping ofD caused by Phythium vexans, leaf blight caused by Phytophthora meadii, leaf blotch caused by Phaeodactylium alpiniae and leaf spots by Eercospora sp., and Sphaceloma cardamomi, leaf rust by Phakospora elettariae, brown spot by Colletotrichum gloeosporioides etc. Most of the diseases occur during the South West monsoon period where heavy rain coupled with high relative humidity predisposes the plant to infection. Since the occurrence and spread of diseases are correlated to weather conditions, integrated disease management strategy adopting cultural, chemical and biological control methods are highly suitable to save the crop from heavy losses. &nbsp

Enhancing shelf life of Trichoderma harzianum by conidial storage in sterile deionized water

In this study T. harzianum conidial suspension was made in different concentrations of cryoprotectants viz., glycerol, glucose, DMSO and deionized distilled water and stored at two different temperatures viz., 25± 1oC and 28-32ºC for more than 720 days for evaluating the shelf life in order to develop a ready to use liquid carrier formulation. The results showed that submerged conidia formulation in cryoprotectants like glycerol, glucose and DMSO preserved the viability for 75 days only when compared to the formulation in sterile deionized water which at 28-32°C retained the viability for 480 days with a viable count of loge= 6.671 (3.2 × 106) and for more than 720 days with a viable count of loge=5.54 (2 × 105) and in 480 days at 25±1°C with a viable count of loge=6.3911 (6.5 × 106) and with a viable count of loge =5.40 (2 × 105) for more than 720 days. The viability was tested in vitro by recovery in TSM and effectiveness was tested in vivo by drenching the suspension on plants and challenge inoculating with Phytophthora capsici after seven days. Challenge inoculation of black pepper plants with P. capsici after drenching with diluted stored suspension gave a disease reduction of 66.67%. Hence, sterile deionized water can be used as a liquid storage medium for the long term storage of T. harzianum culture without loosing the viability and effectiveness of the spores. &nbsp

Phytophthora rot - a new disease of vanilla (Vanilla planifolia Andrews) in India

A severe rot disease affecting beans, leaves and stems of Vanilla planifolia was observed during the South West monsoon season at Koothattukulam and surrounding areas (Emakulam District, Kerala, India). The causal organism was identified as Phytophthora meadii and its pathogenicity was proved. This is the first report of Phytophthora disease of vanilla in India. &nbsp

Evaluation of strobilurin fungicides Ergon 44.3% (w/w) [Kresoxim methyl 500 g L-1 SC] and RIL-070/FI (72WP) against Phytophthora capsici infection in black pepper

Two new strobilurin fungicides viz., Ergon 44.3% (w/w) [Kresoxim methyl 500 g L-1 SC] and RIL-070/FI (72WP) were evaluated in vitro and in planta against Phytophthora capsici causing foot rot disease of black pepper and ED50 and ED90 values were calculated based on the in vitro efficacy. The chemicals were tested in planta using the maximum concentration found effective in vitro. Ergon when tested from 10-6000 ppm of the product in vitro, showed complete inhibition of mycelial growth and sporulation at 6000 ppm. But the zoospore germination was completely inhibited at 2000 ppm. The average ED50 and ED90 values of Ergon were 845.51 and 1740.71, respectively. Foliar spray of the chemical followed by challenge inoculation showed an overall reduction of lesion development by 44.83% over control and maximum inhibition (57.12%) was observed at five days after spraying at a concentration of 7000 ppm. Soil application of Ergon at different concentrations from 6000-8000 ppm showed no infection or mortality at 7000 ppm. RIL-070/FI at different concentrations from 10-500 ppm of the product when tested in vitro against P. capsici showed 100% mycelial inhibition at 50 ppm with ED50 and ED90 values of 22.85 and 45.71, respectively. For inhibition of sporulation, the maximum concentration required was 100 ppm. However, zoospore germination showed 100% reduction at 200 ppm. Foliar spraying of the RIL at concentrations from 100-600 ppm showed lesion development from 0.71 to 100%. When P. capsici was challenged five days after spraying of the chemical, 600 ppm showed 100% inhibition of lesion development. &nbsp

Sclerotium rot - a new disease of vanilla (Vanilla planifolia Andrews) in India

A new type of bean rot affecting vanilla beans was observed in vanilla (Vanilla planifolia) growing tracts of Moovattupuzha in Emakulam District (Kerala, India). The disease was characterized by rotting of bean bunches and subsequent development of thick fungal mat over the bean surface. The causal organism was identified as Sclerotium rolfsii; the fungus was brought into pure culture and its pathogenicity was proved. This is the first report of the fungus on vanilla from India. &nbsp