1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Author: search.filters.author.Mammootty, K P

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    Nursery diseases of black pepper (Piper nigrum L.) in Kerala with special reference to the management of Phytophthora capsici Leonian, emend. Alizadeh and Tsao
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2003) Mammootty, K P; Koshy Abraham
    Nursery diseases are the major limiting factor in the production of quality planting materials of black pepper. Investigations were carried out to study the various diseases occurring in black pepper nurseries of northern districts of Kerala, the effect of nursery practices on the incidence of diseases and to evolve an integrated management strategy against Phytophthora rot in black pepper nursery. Four nursery diseases viz., Phytophthora rot, Colletotrichum rot, Rhizoctonia rot and Sclerotium rot were recorded from different nurseries surveyed. The pathogens causing the diseases were isolated and identified as Phytophthora capsici Leonian emend A. Alizadeh and P.H.Tsao, Colletotrichum gloeosporioides (Penz.) Penz. Sacc., Rhizoctonia solani Kuhn and Sclerotium rolfsii Sacc. Symptomatology of these diseases were studied. The pathogen P. capsid produced symptoms on all parts of the plant, while C. gloeosporioides infected mainly on leaves. R. solani and S. rolfsii infected both leaves and collar regions. The infected plants produced typical symptoms depending upon the pathogen and plant parts affected. Incidence of nursery diseases varied with locations and nursery seasons. Among the nursery diseases noticed during the survey, Phytophthora rot was the most predominant one. Incidence of other three diseases was comparatively less than that of Phytophthora rot. Various nursery practices followed for raising pepper nursenes viz., nursery structures, potting mixture, place of collection of planting materials, variety / cultivar planted, processing of runner vines, treatment of potting mixture, time of planting, frequency of irrigation and application of fungicides had an effect on the incidence of nursery diseases especially Phytophthora rot. However, cuttings raised under high density polyethylene sheet did not show any incidence of diseases. Screening for host resistance indicated tolerant and moderately susceptible reactions of Kalluvally-II and Panniyur-5 respectively against nursery diseases. The biochemical parameters of these genotypes, which impart this type of reactions, were studied in comparison with susceptible Panniyur-l. Total phenols, OD phenol and total free amino acid contents and peroxidase, catalase and esterase activities were more in tolerant Kalluvally-II, while total carbohydrates, starch and acid phosphatase activity were maximum in susceptible Panniyur-l. Reducing sugar content was high in moderately susceptible Panniyur-5. Quantitative estimation of rhizosphere microflora from different pepper nurseries yielded bacteria, actinomycetes and fungi. Fungal antagonists exerted more antagonistic activity against P. capsid both under in vitro and in vivo conditions. Among these two isolates F 14 and F 48 were selected based on their better antagonistic efficiency against P. capsid and they were identified as Trichoderma harzianum Rifai and Trichoderma viride Pers. ex S.F. Gray aggr. The established antagonists T. harzianum and T. viride also exerted good antagonistic efficiency against P. capsid. The native and established antagonists were compatible with Akomin-40 and Ridomil MZ, while Bordeaux mixture and Fytolan were not compatible with any ofthe four fungal antagonists. Better growth and minimum disease incidence in pepper cuttings were recorded when nurseries were raised during February-March. Pepper cuttings raised in solarized potting mixture for 30 days showed more sprouting, better plant growth and less incidence of disease. Integrated management of Phytophthora rot in black pepper nursery was carried out using tolerant Kalluvally-II, moderately susceptible Panniyur-5 and susceptible Panniyur-l. In all the three black pepper genotypes, all the treatments had a significant effect in reducing the incidence of Phytophthora rot when compared with control. The minimum disease incidence in Panniyur-l and Panniyur-5 was recorded in cuttings in treatment T14 (Solarization of potting mixture for 30 days + T. viride + Akomin-40), while in Kalluvally-II it was T20 (Solarization of potting mixture for 30 days + T. harzianum - F14 + Akomin-40). In general, solarization of potting mixture, application of Trichoderma spp. and fungicides like Akomin 40 and / or Ridomil MZ can be used for managing the incidence of Phytophthora rot in black pepper nursery
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    Quick wilt disease of pepper (Piper nigrum Linn)-1 symptomatological studies on the quick wilt disease of pepper
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1978) Mammootty, K P; Abi Cheeran
    The present study on the quick wilt disease of pepper caused by Phytophthora palmivora (Butler) Butler was conducted at the Pepper Research Station, Vellanikkara using Panniyoor-1 pepper variety. The objectives of the investigations were to study the symptoms of the disease and to find out suitable control measures using fungicides. The first visible symptom on leaf, stem and root was noticed 24 to 48 hours; two to five days and 24 to 48 hours respectively after inoculation, depending on the maturity of the plant part. A fully developed lesion had a dark brown hononecrotic centre and plesionecrotic boarder surrounded by yellow halo. The yellow halo was not noticed during prolonged wet and humid conditions. Under these conditions lesions was uniformly brown in colour. Zonations were noticed during the alternate wet and dry conditions. On the stem, branches and roots symptom usually developed as a uniformly brown and dark coloured lesions. Pathogen entered mainly though lower surface of the leaf. After infection, defoliation took place within five to ten days. Development of flaccidity, drooping and defoliation of the leaves were the marked symptoms during the progress of disease when the stem, branches or roots were infected. All the fungicides tested checked the growth of the fungus in vitro for a period of three days. The fungicides when sprayed or drenched two hours before inoculation completely checked the disease. However, there was mild infection on plant where Dithane M-45 was used for drenching the soil. As the interval between the fungicidal spray and inoculation prolonged there was progressive reduction in the control of the disease. None of the fungicides was able to eradicate completely the established pathogen on leaves. When fungicides were applied one day after inoculation there was complete control of the disease on stem. While the control was not complete when it was applied two days after inoculation. All the fungicides except Dithane M-45 completely checked the development of the disease when they were drenched in soil.