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| 001 |
in00000017874 |
| 005 |
20190325090643.0 |
| 008 |
880609s1986 xx a bm 000 0 eng d |
| 035 |
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|a (OCoLC)ocm18062421
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| 035 |
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|9 AAB0352AM
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| 040 |
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|a TXA
|b eng
|c TXA
|d OCLCQ
|d OCLCF
|d OCLCO
|d OCLCQ
|d TXA
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| 035 |
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|a (OCoLC)18062421
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| 049 |
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|a TXAM
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| 099 |
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|a 1986
|a Dissertation
|a S385
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| 100 |
1 |
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|a Schuh, Wolfgang.
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| 245 |
1 |
0 |
|a Epidemiological aspects of sorghum downy mildew, caused by Peronosclerospora sorghi.
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| 264 |
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1 |
|c 1986.
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| 300 |
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|a x, 77 leaves :
|b illustrations ;
|c 29 cm
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| 336 |
|
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|a text
|b txt
|2 rdacontent
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| 337 |
|
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|a unmediated
|b n
|2 rdamedia
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| 338 |
|
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|a volume
|b nc
|2 rdacarrier
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| 500 |
|
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|a Typescript (photocopy).
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| 502 |
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|b Ph. D. in Plant Pathology
|c Texas A & M University
|d 1986
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| 500 |
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|a Vita.
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| 504 |
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|a Includes bibliographical references (leaves 69-76).
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| 520 |
3 |
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|a The distribution and spatial pattern of sorghum plants systemically infected with Peronosclerospora sorghi were determined using Morisita's index of dispersion. A contiguous area of 1300 m² was assessed for disease incidence twice during the growing season at two locations. Each assessment was done using eight quadrat sizes (binary series from 1 m² to 128 m². The spatial pattern of diseased plants was clumped at each date and location as determined by the use of Morisita's index. Several clump sizes, which were in a hierarchical order, were detected at each location. Comparison of clump sizes between assessment dates showed a reduction in average clump size, which was attributed to premature plant death. The spatial pattern of sorghum systemically infected with downy mildew and of soil-residing oospores of Peronosclerospora sorghi was assessed using Morisita's index. A binary series of quadrat sizes, starting at 1 m² and ending at 128 m² for infected plants and 512 m² for the oospores, respectively, formed the basis for the computation. The pattern was clumped (p = 0.01) at all quadrat sizes except the 32-m² and 64-m²quadrat sizes for the oospore distribution pattern. The use of susceptible plants to assess spatial patterns of oospores of P. sorghi instead of direct sampling of soil cores is indicated. The incidence of sorghum downy mildew was influenced by the soil moisture-soil temperature and soil texture-inoculum density complex with statistical significance using logistic regression. The interaction was nonsignificant. A soil temperature-soil moisture combination of 25C and -2/10 bar and soil texture of 80% sand content gave the optimal conditions for disease incidence. Planting dates which are followed by saturated soils and/or soil temperatures below 20 C, or soils with a sand content below 20%, can be classified as disease suppressive. The influence of weather variates on disease incidence of sorghum downy mildew at three locations and over four years was investigated using Principal Component Analysis. Two principal components, derived from the weather data only and representing wet, dry, and cold soil conditions, were used as independent variables in regression analysis and explained 41% of the variation in disease incidence.
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| 650 |
|
0 |
|a Sorghum
|x Diseases and pests.
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| 650 |
|
0 |
|a Downy mildew diseases.
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| 650 |
|
4 |
|a Major plant pathology.
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| 655 |
|
7 |
|a Academic theses
|2 lcgft
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| 700 |
1 |
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|a Frederiksen, R. A.,
|e degree supervisor.
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| 700 |
1 |
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|a Craig, Jeweus,
|e degree committee member.
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| 700 |
1 |
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|a Jeger, Michael J.,
|e degree committee member.
|
| 700 |
1 |
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|a Longnecker, Michael,
|e degree committee member.
|
| 700 |
1 |
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|a Odvody, Gary N.,
|e degree committee member.
|
| 710 |
2 |
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|a Texas A & M University,
|e degree granting institution.
|
| 856 |
4 |
1 |
|u http://hdl.handle.net/1969.1/Dissertations-24009
|z Link to OAKTrust copy
|t 0
|
| 856 |
4 |
1 |
|u http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=753964001&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD
|z Link to ProQuest copy
|t 0
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| 994 |
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|a C0
|b TXA
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| 999 |
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|t 0
|
| 952 |
f |
f |
|p noncirc
|a Texas A&M University
|b J.J. Pickle Campus
|c High Density Repository
|s HDR
|d Remote Storage
|t 0
|e 1986 Dissertation S385
|h Other scheme
|i unmediated -- volume
|m A14839614485
|
| 952 |
f |
f |
|a Texas A&M University
|b College Station
|c Electronic Resources
|s www_evans
|d Available Online
|t 0
|e 1986 Dissertation S385
|h Other scheme
|
| 998 |
f |
f |
|a 1986 Dissertation S385
|t 0
|l Remote Storage
|
| 998 |
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|a 1986 Dissertation S385
|t 0
|l Available Online
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