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ThesisItem Open Access Studies on the pathogenicity and physiology of Cornespora cassiicola (Berk & Curt.) Wei.(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1970) George, P V; KAU; Paily, P VThesisItem Open Access Studies on the production of toxic metabolites by Trichoconis padwickii ganguly in culture filtrate(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1969) Jayachandran Nair, K; KAU; Sam Raj, JThesisItem Open Access Effects of collar mot and ring-barking on the Rhizosphere microflora and certain chemical constituents of sword bean plants(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1968) Kanakambaran, P N; KAU; Sam Raj, JThesisItem Open Access Air spora over rice crop with special reference to Piricularia oryzae Cav.(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1967) Maheswari Amma, S; KAU; Sam Raj, JThesisItem Open Access Mosaic disease of Dolichos bifforus L., transmission , host range and effect of the virus on the host(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1967) Sukumara Dev, V P; KAU; Sam Raj, JThesisItem Open Access Studies on certain chemical constituents of banana leaves in relation to incidence of leaf spot diseases. A note on the fungi occurring on banana(Division of Plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1966) Chandrasekharan Nair, M K; KAU; Sam Raj, JThesisItem Open Access Studies on the helminthosporium Disease of rice detection of mycelium of the fungus in different tissues of the seed obervations on a saltant of Helminthosporium oryzae.(Division of plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1965) Krishnan Kutty Nair, M R; KAU; Sam Raj, JThesisItem Open Access Studies on the phyllosticta leaf spot of ginger(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1981) Premanathan, T; KAU; Peethambaran, C KLaboratory and field experiments of “The studies on the Phyllosticta leaf spot of ginger” were conducted at the College of Horticulture Campus, Vellanikkara during 1979-1981. The first visible symptom of the disease was observed as chlorotic specks. Fructification was more during the later stages of crop growth. The detailed study on the plant and environmental factors influencing the disease development in the field revealed that the average number of leaves per plant has a significant positive correlation with the disease intensity. Koch’s postulate and morphological studies proved that the pathogen causing the disease is Phyllosticta zingiberi Ramakr. Uninjured leaves and first three leaves, even after injury, failed to exhibit the symptoms on inoculation. Conidia germinated by putting forth single or double germtubes. Sucrose solution (1,000 ppm) supported faster and maximum spore germination and the bipolar germination noted was maximum in this solution. The fungus entered the leaf by direct penetration of epidermal cells without appressoria formation. The pycnidiospores and mycelia of the pathogen were found to survive even after seven months in soil under different depths and moisture conditions. The type Maran was found to be the least susceptible followed by Karakkal and Bajpai, whereas type Vengara was the most susceptible one. Out of the 12 fungicides tried, one per cent Bordeaux mixture and 2,000 ppm Bayer 5072 gave cent per cent inhibition of the fungal growth in both solid and liquid media. Antracol 2,000 ppm and panolil above 500 ppm in solid medium; bavistin 2,000 ppm and cuman above 500 ppm in liquid medium gave cent per cent inhibition of fungal growth. In the field trial cuman, was found to be the most effective fungicide in controlling the disease, followed by Bordeaux mixture and panolil. Maximum rhizome yield was noticed in cuman treated plots followed by Bordeaux mixture.ThesisItem Open Access Studies on the control of soft rot of ginger(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1980) Kurucheve, V; KAU; Peethambaran, E KThe present investigation ‘Studies on the control of soft rot of ginger’ was conducted at the Instructional Farm, attached to College of Horticulture, Vellanikkara, Trichur during the year 1978-79. Two varieties of ginger viz. ‘Rio-de-janeiro’ and ‘Maran’ were used for the investigations. The objectives of the investigations were 1) to find out the causal organism of soft rot of ginger in the acid lateritic soils of Vellanikkara 2) to find out suitable control measures against the disease 3) to know whether the fungus could develop resistance against continuous application of fungicides and 4) to find out any adverse effect on the development of ginger rhizomes when the fungicides were applied for controlling the disease. The pathogen responsible for the disease was found to be Pythium aphanidermatum (Edson) Fitzpatrick. More than 90 per cent inhibition of the fungus was observed by agallol, thiride and difolatan at 500 ppm concentration in vitro. Hundred per cent inhibition of the fungus was possible only with 2000 ppm of Cheshunt compound or thiride and with 500 ppm of agallol in vitro. Among the different combinations of Cheshunt compound, agallol and thiride, 100 ppm of agallol plus 100 ppm of thiride was the most effective combination in inhibiting the mycelial growth of the fungus. Seed treatment with 0.25 per cent agallol solution alone was not effective in reducing the disease incidence in the field. The fungicides which were proved very effective in in vitro studies, were again tested under field conditions. They were Cheshunt compound, agallol and thiride. Soil drenching before planting with the above mentioned fungicides reduced the pre emergence rotting considerably. Single application of fungicides either in one, three or four months after planting was not adequate in controlling the disease. A minimum of two post emergence applications i.e. One month and three months after planting either with cheshunt compound or agallol, in addition to pre planting soil drenching were necessary for controlling the disease as well as for getting good yield. P. aphanidermatum did not develop any resistance against the fungicides when they were applied continuously in the field. Adverse effect on the development of ginger rhizomes was not noticed when the fungicides were applied for controlling the soft rot of ginger. The present investigation showed that extent of control varied with the sequence and number of fungicidal applications. Treatments agallol – cheshunt compound, cheshunt compound – cheshunt compound and cheshunt compound – agallol in two times application; cheshunt compound – cheshunt compound – cheshunt compound ; cheshunt compound – agallol – thiride and cheshunt compound – thiride – agallol in three times application and cheshunt compound – cheshunt compound – cheshunt compound – cheshunt compound; agallol – agallol – agallol – agallol and cheshunt compound – thiride – agallol – cheshunt compound in four times application showed a better disease reduction compared to other treatments. The post emergence rotting started appearing from July and peak infection was noticed during August. The variety ‘Maran’ was more resistant to the disease. There was a direct correlation between the disease incidence and continuous rainfall.
