Effect of Bhindi yellow Vein Mosaic virus on its host

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Primary productivity of three vegetable crops as influenced by virus infection

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Trace element studies on some pathogenic fungi

Trace element studies were carried out on five pathogenic fungi-Cercospora hibiscina Ellis and Everh., C. withaniae H. and P. Syd., C. crotalariae Sacc., Monochaetia sp., and Pestalotia theae Sawada. The trace element contaminants from glassware, basal medium, water, glucose and inoculum were removed by various usual means. In addition, EDTA was used for the removal of trace elements from glassware and water. Out of the 15 trace elements tested, Fe, Zn, Cu and Mn were found to be essential for the growth of these five fungi while Mo was found essential only for the growth of C. crotalariae and Monochaetia sp. No other trace element was found to be essential for any of these fungi. Optimum concentrations in ppm of essential trace elements for these fungi were found to be as follows: C. hibiscina: Fe 0.2, Zn 0.01-0.1, Cu 0.01 and Mn 1.0;C. withaniae: Fe 1.0, Zn 1.0, Cu 0.1 and Mn 10.0;C. crotalariae: Fe 0.01, Zn 10.0, Cu 0.001, Mn 0.1, and Mo 0.001;Monochaetia sp.: Fe 1.0, Zn 0.1, Cu 0.1, Mn 0.1 and Mo 0.01; and Pestalotia theae: Fe 10.0, Zn 0.1, Cu 0.01 and Mn 0.01. Concentrations higher than the optimum were inhibitory to the respective fungi

Destruction of chlorophylls a and b in virus infected leaves

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The potential for pollen-borne virus transfer in a plum orchard infected with Prunus necrotic ringspot virus

Prunus necrotic ringspot virus (PNRSV) is borne in stonefruit pollen. Previous work has shown that virus particles can enter cucumber seedlings when virus-bearing pollen grains contact puncture holes made in plant cells by thrips feeding. Stonefruit plant parts on which pollen is deposited and thrips spend considerable time feeding, are likely sites of PNRSV inoculation. The principal agents of pollen deposition may therefore play a key role in PNRSV epidemiology. We determined the principal sites of pollen deposition on Japanese plum trees and the major pollen depositing agents in a PNRSV-infected orchard in southeastern Queensland. Plum pollen was deposited mostly onto flowers, with few grains being found on leaves or stems. Within the flowers, pollen grains were distributed mostly on the petals, but some were found on the sepals, filaments and carpels. Honey bees were the most frequent visitors to plum flowers and they deposited more than any other insects. Flies visited flowers at low frequencies and also deposited pollen. Significant amounts of pollen were deposited onto flowers by unidentified nocturnal agents. Thrips were not observed during the study period, although they were present in the orchard. Previous studies have assumed that thrips carry virus-bearing pollen as well as bring it into proximity of feeding wounds. Our results suggest that, although thrips carriage of pollen may occur, it is not necessary for PNRSV spread in stonefruit orchards