Search

Black pepper is the most important and widely consumed spice in the world. Insects and diseases are the major concerns for black pepper production, among the many variables causing a decline in black pepper productivity. The major diseases that affect black pepper are foot rot (Phytophthora capsica) and anthracnose (Colletotrichum gloeosporioides). Early and precise diagnosis of diseases is crucial as it will enable the farmers to make timely interventions. In the current scenario, the application of image processing and deep learning techniques for the automatic detection of plant diseases emerges as a solution capable of promptly delivering interventions in time-sensitive scenarios, given its capacity to deliver performance approaching expert levels. Through this study, a deep learning-based approach has been developed to classify black pepper diseases based on leaf images. A model has been developed to detect the two major diseases of black pepper, i.e., anthracnose and foot rot diseases, using a Convolutional Neural Network (CNN) in Kerala, India. We have collected 2786 leaf images from different black pepper farms in Kerala, belonging to three classes of pepper diseases and one healthy leaf class in total. The classes of leaf diseases considered include an early and advanced stage of anthracnose, and Phytophthora foot rot. As the accuracy of the model increases with the number of images, different image augmentation techniques are performed on the originally captured images to generate a total of 18,234 images. The developed CNN model has been compared with eight other pre-trained state-of-the-art models, such as VGG16, VGG19, ResNet50, ResNet50V2, MobileNet V2, DenseNet121, InceptionV3, and Xception. The result shows that the developed CNN model attained a higher classification accuracy, precision, recall, and F1-score of 98.72%, 99.28%, 97.65%, and 98.66% respectively, on the unseen test dataset. A web application named "Black pepper Disease Identification App" for demonstrating the proposed model is developed. According to an overall performance assessment, deep learning is an effective technique for classifying black pepper diseases based on leaf images and identifying them in their early stages. Based on the overall performance, the newly developed model is found to be efficient in classifying the selected pepper diseases. The proposed model holds significant promise for enabling the timely identification of diseases with minimal human intervention. Its deployment benefits both researchers and farmers by facilitating prompt disease detection directly in the field. [ABSTRACT FROM AUTHOR] more...

Banana bract mosaic virus (BBrMV) infection results in characteristic reddish streaks on pseudostem and chlorotic spindle lesions on leaves leading to traveler's palm appearance and complete crop loss depending on the stage of infection in banana plants. Here, we discuss the influence of P. indica colonization (a beneficial fungal root endophyte) on BBrMV infection, specific viral component genes responsible for symptom development, chlorophyll and carotenoid biosynthesis, and degradation in BBrMV-infected banana plants. P. indica colonization significantly and substantially reduced the severity of Banana bract mosaic disease (BBrMD) in addition to increased growth, development and yield of banana plants. The percent disease incidence (PDI) of BBrMV ranges from 50 to 70 per cent in plants raised from suckers and from 58 to 92 per cent in TC plants under artificial inoculation. P. indica-colonized plants inoculated with BBrMV resulted in an enhanced plant height, root length, leaf width, and leaf length of 72, 88, 90, and 60 per cent, respectively, compared to BBrMV alone-infected banana plants along with the reduced disease severity. BBrMV infection showed a drastic decrease of chlorophyll a, chlorophyll b, and total chlorophyll contents by down-regulating chlorophyll biosynthesis (Chlorophyll synthase—CHLG) and upregulating chlorophyll degradation (Chlorophyllase—CLH1 and CLH2 and Pheophytin pheophorbide hydrolase—PPH) genes; and by up-regulating carotenoids biosynthesis (Phytoene synthases—PSY1 and PSY2) and down-regulating its degradation (Phytoene desaturase—PDS) genes compared to P. indica-colonized banana plants challenge inoculated with BBrMV. P. indica also inhibited the expression of the viral genes (P3 and HC-Pro) involved in symptom development. P. indica-colonized banana plants reduced the BBrMV symptoms severity by enhancing chlorophyll biosynthesis; and decreasing chlorophyll degradation and carotenoid biosynthesis and degradation; and inhibiting the viral genes responsible for symptom development in addition to enhanced growth and yield of banana plants. [ABSTRACT FROM AUTHOR] more...

Chemical fungicides used in plant disease management may have deteriorative effects on humans, animals, and the environment. The use of native strains of Trichoderma spp. against plant diseases may help to reduce the dependence on chemical fungicides. In this study, eleven novel isolates of Trichoderma spp. from virgin forest soils of different agro-climatic zones of Kerala were characterized and evaluated for their efficacy against damping off disease of tomato caused by Pythium aphanidermatum under in vitro and in vivo; and also, against wilt pathogen, Fusarium oxysporum under in vitro conditions. Dual culture assay showed that all the Trichoderma isolates were found to inhibit the growth of P. aphanidermatum and F. oxysporum under in vitro conditions with multiple modes of action. The mycelial colour, texture, and conidial characters varied among all the isolates. The volatile metabolites by isolates of Trichoderma spp. also showed in vitro inhibition of the pathogens. Seed treatment (20 g kg-1) and potting medium addition @ 2 % (w/w) of isolates TRMW-2, TRKR-2, TRPN-3, TRPN-11 and TRPN-17 could effectively reduce pre- and post-emergence damping off of tomato. Among them, isolates TRMW-2, TRKR-2, and TRPN-11 were the most effective ones in reducing pre- and post-emergence damping off to about 72 and 90 percent respectively. Molecular identification of the isolates of Trichoderma spp. using ITS universal primers revealed similarity with certain reference strains of the NCBI Genbank database. [ABSTRACT FROM AUTHOR] more...

Cardamom plantations are subjected to constant threat due to the Fusarium rot disease caused by Fusarium oxysporum Schlecht which is pronounced during summer months. The current study deals with the identification of an effective and ecofriendly management practice for the disease through the use of biocontrol agents. Survey conducted between February and May 2019 revealed maximum disease severity and incidence in Pampadumpara panchayat of Nedumkandam block (84.40% and 100%) and minimum in Erattayar panchayat of Kattappana block (50.40% and 60.00%). A pot culture experiment was conducted to study the effect of three bioagents (Glomus fasciculatum, Trichoderma asperellum and Pseudomonas fluorescens) individually as well as in combinations. Root inoculation of G. fasciculatum with basal application and spray with P. fluorescens as well as root inoculation of G. fasciculatum along with basal application of T. asperellum and P. fluorescens spray were identified to be effective against the disease. Disease suppression by the above bioagents was facilitated by reduced pathogen antagonist ratio in the soil, high level of mycorrhizal colonization in the roots and enhanced biochemical activity of defense enzymes like peroxidase, poly phenol oxidase and phenylalanine ammonia lyase in the plants. [ABSTRACT FROM AUTHOR] more...

Trichoderma spp. are long been recognized as efficient fungal biocontrol agents for the control of plant disease and for their ability to increase plant growth and development. Management of soil borne diseases has become very much important since it causes high crop yield losses. The present study was carried out to isolate Trichoderma spp. from soil samples collected from different locations of Kerala and to test their in vitro efficacy against soil borne pathogens viz., Pythium aphanidermatum and Rhizoctonia solani. The Trichoderma spp. was isolated on Trichoderma Selective Medium (TSM) and observed that the isolates differed in radial growth and colony characters such as colony colour, texture and sporulation. In vitro studies revealed the potential of Trichoderma isolates against soil borne pathogens. Isolates TRPN3 and TRPN7 exhibited no sporulation and white mycelial colour. Isolates which completed their growth at four days after inoculation include TRKR1, TRPN3, TRPN7, TRPN10 and TRPN18. Biocontrol activities against different pathogens resulted in inhibition of pathogens. Maximum inhibition percentage was observed by the isolates TRPN7, TRPN15 and TRKR2 against both the pathogens. The maximum inhibition exhibited against both the pathogens is due to the antagonistic property displayed by the isolates. [ABSTRACT FROM AUTHOR] more...

Basal stem rot and blight disease incited by Sclerotium rolfsii resulted in significant crop loss in vegetable cowpea. Among the different levels of pH tested under in vitro conditions, pH 6.0 was revealed to be optimum for the mycelial growth, whereas pH 7.0 supported maximum sclerotia formation. Soil moisture of 35 to 50 per cent was ideal for early disease expression and establishment. A minimum level of two per cent fungal inoculum multiplied in sand oats medium resulted in complete disease incidence. Among the botanicals tested in vitro, garlic bulb extract (1%) and garlic creeper leaf extract (5%) revealed cent per cent inhibition of mycelial growth and sclerotia formation of the fungus. Both the extracts also inhibited the mycelial regeneration from sclerotia. Thus, garlic bulb and garlic creeper were revealed to be potent botanicals which can be used as effective alternatives to soil fumigants for the management of S. rolfsii. [ABSTRACT FROM AUTHOR] more...

Symptoms of excessive shoot proliferation were observed in the Njallani cultivar of small cardamom accompanied by stunting of stalks with fewer degenerated capsules at Nedumkandam Panchayat of Idukki district of Kerala in 2017. Five symptomatic Elettaria cardamomum shoot proliferation (ECSP) plant samples were collected and processed for DNA extraction and PCR assays utilizing universal phytoplasma 16S ribosomal-specific primers pair, P1/P7 followed by R16F2n/R16R2. Sequence comparison analysis of the R16F2n/R16R2 region of 16SrRNA gene showed 100% sequence identity with the 'Candidatus Phytoplasma australasia'- related strain. Phylogeny and virtual RFLP analyses of 16S rRNA gene sequences confirmed the association of 'Ca. P. australasia' strain subgroup D with ECSP disease. The association of 16SrII group was further established and validated by amplifying phytoplasma-specific multilocus candidate genes by utilizing specific primers of secA, secY, SAP11, and tuf genes. The multilocus gene sequence comparison analysis again confirmed the association of 'Ca. P. australasia' with the ECSP phytoplasma isolate. This is the first report of phytoplasma association with small cardamom. [ABSTRACT FROM AUTHOR] more...