Effect of Potato Virus Y and Tobacco Mosaic Virus on Field - Grown Burley Tobacco

SIEVERT, R. C. 1978. Effect of potato virus Y and tobacco mosaic virus on field-grown burley tobacco. Phytopathology 68: 823-825. Yield, grade index, crop index, value per kilogram, and tobacco had less nicotine and TMV-infected tobacco had less value per hectare were reduced when Burley 37 became a-amino nitrogen, but tobacco infected with TMV+PVY had infected with tobacco mosaic virus (TMV), potato virus Y less water-soluble acids, nicotine, phenols, and a-amino (PVY), or both. A greater reduction was caused by PVY than nitrogen and a lower percentage of its total nitrogen was by TMV, but the two viruses together caused the greatest soluble. Tobacco infected with TMV+PVY had more nitrate reduction. Similarly, TMV+PVY caused greater variation and insoluble nitrogen. Flowering was delayed in plants from normal of chemical constituents than did either PVY or infected with TMV or TMV+PVY, but PVY infection alone TMV alone. Compared to healthy tobacco, PVY-infected had little effect on flowering. Additional key words: Nicotiana tabacum, double infection, virus interactions, veinbanding. Tobacco mosaic virus (TMV) and potato virus Y Cumberland silt loam soil. Only plants in the center two (PVY) are known to infect many species of plants, rows of each plot were inoculated; the outer two rows including several commercial crops. Losses of tobacco served as barriers to minimize spread of the viruses to from these viruses have been estimated, but little is known adjacent plots. The treatments consisted of inoculating about their effect on growth, yield, and quality of plants with TMV, PVY, or TMV+PVY, or leaving them tobacco. Thomson and Wright (9) reported reductions in noninoculated. The treatments were replicated three weight, leaf area, and smoking quality of flue-cured times in a randomized block design. The end plants of tobacco infected with PVY. A study in the greenhouse each treatment row were not harvested; thus, data were showed that plant height, plant weight, and leaf weight of obtained from 80 plants in each plot. susceptible cultivars were reduced by TMV and PVY, and The experiment was conducted first in 1968 and was that together they generally had a synergistic effect on a repeated in 1969. Seedlings were transplanted 28 May cultivar susceptible to both viruses (7). Other recent 1968 and 30 May 1969. The plants were inoculated 28 studies have determined the effect of TMV on the June 1968 and 26 June 1969, by rubbing two leaves per chemical characteristics of flue-cured tobacco (5) and the plant with a virus suspension prepared from systemically effect of early harvest on tobacco infected with PVY (8). infected plants grown in the greenhouse. This inoculum The purpose of this study was to ascertain some of the was prepared by homogenizing one part infected plant effects of these viruses on production and on selected material in a blender with about five parts 0.1% Na 2SO 3 chemical constituents, primarily the nitrogenous (w/ v), filtering the homogenate through cheesecloth, and components, total phenols, and aklakoids of burley adding silicon carbide, average particle size 43 Am (320tobacco, grit). Normal cultural and handling practices were followed MATERIALS AND METHODS for growing, harvesting, and curing the tobacco. Burley tobacco (Nicotiana tabacum L. 'Burley 37') (Bu Flowering plants were counted on 14 August 1969. 37) was used because it is susceptible to both TMV and The yield and grade index were determined from the PVY and resistant to several other tobacco diseases. The cured tobacco. The crop index, value per kilogram, and test plots were four adjacent 42-plant rows in a value per hectare were calculated for each treatment. The grade and crop indices were obtained as previously 00032-949X/78/000 140$03.00/0 described (6). Composite samples of the cured leaf were Copyright © 1978 The American Phytopathological Society, 3340 analyzed for selected constituents utilizing the following Pilot Knob Road, St. Paul, MN 55121. All rights reserved, methods: a-amino nitrogen, pH, total nitrogen, and