MSc

The study entitled ‘Eco-friendly management of Fusarium rot in cardamom and its impact on soil health and plant defense mechanism’ was conducted at College of Agriculture, Vellayani and Cardamom Research Station Pampadumpara during 2018- 2020 with the objective to assess Fusarium rot severity and pathogen variability in Idukki district, develop an effective ecofriendly management practices for the disease and study the impact of the practices on the soil and plant health.
Six isolates of Fusarium oxysporum Schlecht were obtained, three each from infected pseudostem and roots collected from Kattapana and Nedumkandam blocks of Idukki district. The isolate, Fp1 from pseudostem (Pampadumpara panchayath) was identified as most virulent based on virulence rating (viz., days taken for symptom development, lesion length, mycelial growth), and was used for further studies. Inoculation of the root isolate (Fr1) also produced typical lesion on pseudostem indicating that the, fungus can also attack pseudostem besides the roots. But the root isolate took more days (40 days) for symptom development compared to pseudostem isolate (29 days). The morphological characters including the colour, colony characters, hyphal and conidial characters as well as rate of growth in Petri dish confirmed the fungus as F. oxysporum. In vitro studies revealed that the isolates from pseudostem and roots showed significant variation in their morphological, cultural and pathological characters.
A pot culture experiment was conducted to assess the efficacy of selected bioagents (individually and in combination) for the management of the disease at CRS Pampadumpara in CRD using nine treatments with three replications. Pathogen inoculum (150 gm/10 kg soil) multiplied in sand-maize flour medium was standardised as the inoculum level enough for cent per infection on the pseudostem resulting in complete crop loss. Soil application of vermiculite based AMF inoculum (20 g) with @ 2% Pseudomonas fluorescens (1 L/10 kg soil) per 10 kg soil at the time of planting along with 2% P fluorescens spray @ 0.5 L/ plant at monthly interval for three times resulted in effective disease management (disease incidence: 40% and disease severity: 24.26%) compared to the inoculated control (disease incidence: 100% and disease severity: 69.38 %). Studies on the population dynamics of the pathogen and the
biocontrol agents at periodical interval upto three months revealed significant reduction in the pathogen antagonist ratio and enhancement in AMF colonization of the treatment plants. Among the best treatment the combination of AMF and P. fluorescens resulted in good biometric characters of the treatment plants (plant height: 96.50 cm ,leaf length: 62.50 cm and number of leaves: 15.75) compared to control (plant height: 41 cm ,leaf length: 30 cm and number of leaves: 7.50) through enhancement of soil nutrients (P, K, Ca and Mg) and plant nutrient status (K, Mg, S and B) compared to control plants. Laboratory studies also revealed the induction of defense related enzymes (phenol, ortho dihydroxy phenol, peroxidase, polyphenol oxidase, and β 1,3 glucanase) in high concentration as a response to the application of above treatments.
Thus, the present study revealed that Fusarium rot of cardamom a devastating disease can be effectively managed by soil application of vermiculate based AMF inoculum (20 g) with 2 per cent P. fluorescens (1L/10 kg soil) per 10 kg soil at the time of planting along with 2 per cent P. fluorescens spray at 0.5 L per plant at monthly interval for three times; this treatment also resulted in good vegetative growth of cardamom plants therefore this can be used as an ecofriendly management strategy for the production of good quality cardamom.