Spread of maize dwarf mosaic virus in sorghum /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The roles of resident and transient aphids in the spread of maize dwarf mosaic virus (MDMV) in sorghum were investigated. Attempts were made to reduce secondary spread of MDMV within test plots in order to estimate the importance of secondary spread and to evaluate possible control measures. Application of insecticide to eliminate or prevent aphid colonization resulted in no significant reductions in maize dwarf mosaic (MDM) incidence among treatments. This suggests that resident aphids did not significantly contribute to MDMV spread within the plots. In one experiment, the use of a systemic insecticide resulted in a 2.5% increase in MDM incidence. This was probably due to agitation of the aphid vectors resulting in increased probing activity. Grain yields were much greater in the insecticide-treated plots due a reduction in greenbug damage. No significant reduction in MDM incidence was seen in sorghum planted in alternate rows with a highly resistant sorghum compared to sorghum planted in alternate rows with an infection-susceptible sorghum. This indicates that immediately neighboring rows of sorghum did not serve as significant sources of any secondary spread of MDMV that may have occurred locally. In other tests, dilution of susceptible sorghum among resistant or immune sorghum in mixed stands did not significantly reduce MDM incidence among the susceptible sorghum. No dilution or interference of secondary spread was detected suggesting that little or no secondary spread was occurring within the plots. Aphid trapping indicated massive aphid migrations during the first 3 to 4 weeks of the growing season while the sorghum was most susceptible to infection. A survey indicated that very little aphid colonization and increase occurred during this period, suggesting that resident aphids contributed little to the spread of MDMV. A range of plant densities caused by poor seed germination and replanting resulted in different MDM incidences. The data suggest that relatively uniform numbers of viruliferous aphids entered each plot resulting in higher proportions of infection in the less dense stands. Ordinary runs analyses of healthy and infected plant distributions suggested random infections with no indication of clustering caused by to local secondary spread. |
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| Item Description: | Vita. "Major subject: Plant Pathology." |
| Physical Description: | xiii, 89 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |