This is to certify that thethesis entitledTHE ROLE OF 7-0XABICYCLO[2.2.1]HEPTANE-2,3-DICARBOXYLIC ACID(ENDOTHALL)IN ANNUAL BLUEGRASS (POA ANNUA L.) CONTROL IN TURFpresented byALFREDJ.TURGEONhas been accepted towards fulfillmentof the requirements forPh.D.DateSeptember3, 19710-7639degree inCrop&Soil SciencesABSTRACTTHE ROLE OF 7-0XABICYCLO[2.2.I]HEPTANE-2,3-DICARBOXYLIC ACID (ENDOTHALL) IN ANNUALBLUEGRASS (POA ANNUA L.) CONTROL IN TURFByAlfred J. TurgeonExperiments were conducted to evaluate the potential of7-oxabicyclo[2.2.I]heptane-2,3-dicarboxylic acid (endothall)for controlling Poa annua L. infestations in Poa pratensis L.and Agrostis palustris Huds. turfs. The absorption, trans-location and metabolism of endothall and the effects of endo-thall on photosynthesis, respiration and transpiration werestudied to determine whether they contributed to selectivityamong these 3 grasses.Foliar applications of endothall to single-plant sandcultures of the 3 turfgrass species produced a selectivegrowth suppression of Poa annua at certain rates and frequen-cies of application. Field spraying of the herbicide pro-duced variable results which were highly dependent upon theseason of application.Root applications to plants in sand culture resulted ina selective kill of Poa annua within a certain concentrationrange of the herbicide. A granular formulation of endothallprovided selective control of Poa annua in some field andgreenhouse studies. Variables affecting this response includ-ed: watering frequency prior to application, the nature ofthe underlying soil, and plant variability within the Poaannua species.The selectivity of endothall in turf was attributed, inpart, to differential absorption and metabolism of the herbi-cide from root applications and the greater sensitivity ofthe physiological systems of Poa annua to endothall.Following foliar sprays of endothall, a reduction ofphotosynthesis and an increase in respiration were observedin Poa pratensis and Agrostis palustris. These effects dis-appeared within 48 hr. Conversely, the photosynthetic acti-vity of Poa annua was considerably below normal 48 hr aftertreatment. Root applications resulted in a continuousdecrease of photosynthesis in Poa annua, with little effecton the other grasses. Transpiration was severely reducedin Poa annua, and to a lesser extent in Poa pratensis, fromroot applications of endothall. In contrast, foliar sprayscaused no significant effect on transpiration water loss byall 3 turfgrass species.THE ROLE OF 7-0XABICYCLO[2.2.l]HEPTANE-2,3-DICARBOXYLIC ACID (ENDOTHALL) IN ANNUALBLUEGRASS (POA ANNUA L.) CONTROL IN TURFByAlfredJ.TurgeonA THESISSubmitted toMichigan State Universityin partial fulfillment of the requirementsfor the degree ofDOCTOR OF PHILOSOPHYDepartment of Crop and Soil Sciences1971ACKNOWLEDGMENTSTo my wife, Jean, for her continued encouragement andassistance in the preparation of this manuscript;To Dr. D. Penner for his advice and assistance in thelaboratory investigations that constituted an importantpart of the research;To Dr. J. Beard for his council through the Doctoralprogram;To Drs. P. Rieke, R. Kunze and J. Vargas for theirparticipation on my graduate committee and their suggestionsthererelatingiAnd to Dr. W. Meggitt, major professor, constructivecritic, and friend;I wish to extend my most sincere appreciation.iiSectionI.II.TABLE OF CONTENTSINTRODUCTIONLITERATURE REVIEW13The Plant - Annual Bluegrass (poa annua L.) 3III.DescriptionOrigin and DistributionReproductionSeed GerminationGrowthSusceptibility to Environmental StressSubspecies VariabilityCultural ControlChemical ControlThe Herbicide - EndothallApplications to TurfAbsorptionTranslocationMetabolismPhysiological Effects~ffiTERIALSAND METHODSSelectivityDifferential Growth ResponseSpray Volume and Surfactant EffectsTemperature EffectsSoil Composition EffectsMoisture EffectsSubspecies VariabilityField StudiesPhysiological InvestigationsAbsorptionTranslocationMetabolismPhotosynthesis and RespirationTranspirationiii3345678910121214141516192020212222232424262628293031SectionIV.V.RESULTS AND DISCUSSIONSelectivityDifferential Growth ResponseSpray Volume and Surfactant EffectsTemperature EffectsSoil EffectsMoisture EffectsSubspecies VariabilityField StudiesPhysiological InvestigationsAbsorptionTranslocationMetabolismPhotosynthesis and RespirationTranspirationSUMMARY AND CONCLUSIONSBIBLIOGRAPHYiv3333333841444649536161637880899197Table1234567891011LIST OF TABLESPlant height of 3 turfgrass species in 31 daysfollowing 1, 2 or 3 foliar applications ofendothall at weekly intervals.Root dry weights of 3 turfgrass species in 31days following 1, 2 or 3 foliar applicationsof endothall at weekly intervals.Effects of root-applied endothall on 3 turf-grass species 3 weeks after treatment.Plant height of 3 turfgrass species aftertreatment with endothall at 2.2 kgjha appliedin 3 spray volumes.Plant height of 3 turfgrass species aftertreatment with endothall with or without sur-factant.Effects of foliar-applied endothall after 7days on the plant height of 3 turfgrassspecies under 3 temperatures.Temperature effects on plant injury measured7 days after root treatment with endothall.Effects of clay and organic matter on theefficacy of root-applied endothall on Poaannua.Effects of granular endothall on plugs of 3turfgrass species growing in sandy loam (SL)and muck (M) soils.Effects of watering schedule on the suscepti-bility of the 3 turfgrass species to injuryfrom granular endothall applied at the rateof 18 kg/ha.Effects of foliar-applied endothall on thepercent of Poa pratensis and Poa annua in afairway turf (site #1) 6 months after treat-ment.v3435394042434547485054Table12131415161718Effects of 7 foliar applications of endothallat 2-week intervals on the percent compositionof Poa pratensis and Paa annua in a turf (site#4) •Effects of granular endothall on Poa annuagrowing on muck (site #5) vs a sandy loam(site #6) soil.Foliar absorption of endothall by 3 turfgrassspecies.Retention of 14C-endothall by the leaves of 3turfgrass species.Root absorption of 14C-endothall by 3 turf-grass species.Metabolism of 14C-endothall to l4C02by 3turfgrass species in 4 hours.Transpiration water loss by 3 turfgrass spe-cies after foliar and root treatments withendothall.vi57596262647990LIST OF FIGURESFigure1 Effects of root-applied endothall on Poapratensis, Agrostis palustris and Poa-annua,from top to bottom, 3 weeks after treatment. 372 Effects of root-applied endothall on