Browsing by Author "Radha, K."

Now showing 1 - 20 of 41
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    Bud rot disease of coconut—A reappraisal of associated factors
    (2007-02-08) Radha, K.; Thomas Joseph
    Bud rot disease of coconut caused by Phytophthora palmivora (Butl,) Butl. often tends to be fatal. None of the environmental factors associated with the disease was found to be solely responsible for its development. Manifestation of the disease requires a combination of favourable factors, of which high relative humidity and low temperature are the most important factors. Number of "favourable days" determined the incidence and severity of the disease, which in turn was dependent on the monsoon rains. Palms aged 3-20 years exposed to suitable microclimate were the most susceptible. The role of Phytophthora palmivora in the incidence of the disease, the nature of damage, and the possible implication of secondary invaders, such as bacteria in aggravating symptoms have been assessed. Production of oospores in infected tissues suggests the mode of survival of the pathogen in the cabbage of affected palms. Under favourable conditions an infection cycle could be completed in about a week by the pathogen.
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    Coconut root (wilt) disease in Trichur district 2: Observations on disease recurrence
    (2007-02-08) Kochu Babu, M.; Radha, K.; Rethinam, P.; Antony, K.J.
    Four hundred coconut root [wilt] affected palms distributed in eight villages north of Karuva-nnur river in Trichur district Kerala were eradicated to prevent the spread of the disease further north. Observations on disease recurrence in the affected gardens were recorded periodically. Out of 209 gardens from where 400 root [wilt] disease affected palms were eradicated 193 gardens [92.4%] remained free of disease after four years. The gardens with disease recurrence are located in low lying areas of hill slopes and riverbed. Eradication is more effective in gardens where initial incidence of disease was low. Young palms are more susceptible to the disease. Within the diseased gardens spread of the disease was erratic.
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    Coconut root (wilt) disease in Trichur district- Observations on disease recurrence
    (1985-08) Kochu Babu, M.; Radha, K.; Rethinam, P.; Antony, K.J.
    Four hundred coconut root [wilt] affected palms distributed in eight villages north of Karuvannur river in Trichur district Kerala were eradicated to prevent the spread of the disease further north. Observations on disease recurrence in the affected gardens were recorded periodically. Out of 209 gardens from where 400 root [wilt] disease affected palms were eradicated 193 gardens [92.4%] remained free of disease after four years. The gardens with disease recurrence are located in low lying areas of hill slopes
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    Coconut root [wilt] disease in Trichur district
    (2007-02-08) Rethinam, P.; Kochu Babu, M.; Radha, K.
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    Computation of disease index of root (wilt) disease of coconut
    (2007-02-08) George, M.V.; Radha, K.
    The major foliar symptoms associated with the root (wilt) disease of coconut are flaccidity, yellowing and necrosis. Data available from a previous study on the diagnostic symptoms of the disease on 7,168 palms (both adult and young), growing under varying ecological con- . ditions formed the basis for fixing up the importance of the different symptoms. On the basis of their frequency of occurrence and intensity, due weightage and grade points were assigned to each symptom. A formula was evolved to index the disease intensity, by adding the weighted average grade points of the different symptoms on all the leaves of a palm, thereby reducing the disease-intensity complex to a single numerical expression.
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    Computation of disease index of root (wilt) disease of coconut
    (1973-04) George, M.V.; Radha, K.
    The major foliar symptoms associated with the root (wilt) disease of coconut are flaccidity, yellowing and necrosis. Data available from a previous study on the diagnostic symptoms of the disease on 7,168 palms (both adult and young), growing under varying ecological conditions formed the basis for fixing up the importance of the different symptoms. On the basis of their frequency of occurrence and intensity, due weightage and grade points were assigned to each symptom. A formula was evolved to index the disease intensity, by adding the weighted average grade points of the different symptoms on all the leaves of a palm, thereby reducing the disease-intensity complex to a single numerical expression.
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    Contain coconut root (wilt) disease by eradication of diseased palms
    (1985-10) Radha, K.; Kochu Babu, M.; Rethinam, P.; Antony, K.J.; Sukumaran, C.K.
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    Contain coconut root (wilt) disease by eradication of diseased palms
    (2007-02-08) Radha, K.; Kochu Babu, M.; Rethinam, P.; Antony, K.J.; Sukumaran, C.K.
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    Diagnostic symptoms of root (wilt) disease of coconut
    (1972-05) Radha, K.; Lal, S.B.
    Symptoms of the root .(wilt) disease of coconut {Cocas muffera L.) are complex and variable. Of the visual symptoms, Saccidity of leaves or ribbing of leaflets, yellowing of leaves and marginal necrosis of leaflets are frequently associated with the advanced stages of the disease. A comparative assessment of the importance of these foliar symptoms was made on over 7,000 pabns of varying age, growing under different soil conditions, Flaccidity or ribbing of leaflets was the common symptom. In a majority of young palms at an early stage of the disease, this appeared to be the .only symptom. Foliar yellowing and marginal necrosis were not typical of the disease but they set in with the advancement of age and disease, which ultimately completed the disease syndrome. Foliar yellowing was considered to be a delayed expression of nutrient deficiency. Marginal necrosis of leaflets was attributed to fungal infection.
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    Diagnostic symptoms of root (wilt) disease of coconut
    (2007-02-08) Radha, K.; Lal, S.B.
    Symptoms of the root .(wilt) disease of coconut {Cocas muffera L.) are complex and variable. Of the visual symptoms, Saccidity of leaves or ribbing of leaflets, yellowing of leaves and marginal necrosis of leaflets are frequently associated with the advanced stages of the disease. A comparative assessment of the importance of these foliar symptoms was made on over 7,000 pabns of varying age, growing under different soil conditions, Flaccidity or ribbing of leaflets was the common symptom. In a majority of young palms at an early stage of the disease, this appeared to be the .only symptom. Foliar yellowing and marginal necrosis were not typical of the disease but they set in with the advancement of age and disease, which ultimately completed the disease syndrome. Foliar yellowing was considered to be a delayed expression of nutrient deficiency. Marginal necrosis of leaflets was attributed to fungal infection.
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    Disease incidence and yield of coconut in relation to foliar spiral
    (2007-02-08) Radha, K.; Pandalai, K.M.
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    Distribution and symptoms of the coconut root wilt, Thatipaka and Thanjavur wilt diseases and their potential danger in genetic transfer
    (2007-02-08) Radha, K.; Koshy, P.K.
    For these diseases, curative or prophylactic control measures do not exist. As such the only precaution which can be adopted is to avoid collection of seednuts/ pollen from diseased localities within 200 km. International cooperation in funding the collection, maintenance and multiplication of indigenous and exotic germplasm is required as most of the coconut growing countries do not have enough available funds for this. Locating world germplasm collection of coconut at two centres and establishing regional germplasm centres for every region will be of immense value in view of the reported occurrence of an increasing number of seed borne and offer diseases of uncertain etiology.
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    Effect of manuring and intercultivation on the yield of coconut in relation to leaf rot and root (wilt) diseases
    (2007-02-08) Sahasranaman, K.N.; Radha, K.; Pandalai, K.M.
    The effect of (1) manuring with standard dose of NPK fertilizers at the rate of 0.55 lb. N, 0.56 1b. P2O5 and 1.0 Ib. K2O plus intercultivation, (2) heavy dose of NPK fertilizers 1.5 and 3.0 Ib. of N and P2OB, and 3.0, 4.5 and 6.0 lb. of K2O plus intercultivation and (3) no manuring and no cultivation, on the yield and foliar disease symptoms of four groups of palms affected by root (wilt) disease as well as leaf rot have been recorded. Manuring with standard dose of fertilizers plus intercultivation was found to be beneficial in maintaining an economic yield and the general health of the palms, although it has not been able to check the progress of the disease to any appreciable extent in the case of trees in an advanced stage of either of the diseases. A higher dose than the standard dose of manures is not advocated as it seemed, under the conditions of the experiment, to aggravate disease conditions and reduce yield. This probably arises due to the antagonists action of increased potassium on the magnesium.
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    Etiology of the root (wilt) disease of coconut palm
    (2007-02) Lal, S.B.; Radha, K.; Shanta, P.
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    Fungi associated with the coconut palm (Cocos nucifera L.)
    (2007-02) Thomas Joseph; Radha, K.
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    The Genius Rhizoctonia in Relation to Soil Moisture
    (1957) Radha, K.; Menon, K.P.V.
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    The Genus Rhizoctonia in Relation to Soil Moisture - Studies on Rhizoctonia solani and Rhizoctonia bataticola
    (1957) Menon, K.P.V.; Radha, K.
    The saprophytic activity of R. solani and R. bataticola, the organisms associated with the Coconut Root (wilt) disease was investigated in relation to soil moisture. Both the organisms made nur mycelial spread in natural soil. In autoclaved soil the test fungi grew well under a wide range, of soil moisture. Evaluation of the soil microflora and the microbiologica activity in the soil under different moisture conditions revealed that the activity of the test fungi is correlated with the microbial status of the soil which is directly influenced by the moisture content of the soil.
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    Major Coconut Diseases and their Control
    (2007-02) Radha, K.