Characterization of Organosilicone Surfactants and Their Effects on Sulfonylurea Herbicide Activity

dc.contributor.authorSun, Jinxiaen
dc.contributor.committeechairFoy, Chester L.en
dc.contributor.committeememberGrayson, Randolph Larryen
dc.contributor.committeememberHess, John L.en
dc.contributor.committeememberHatzios, Kriton K.en
dc.contributor.committeememberOrcutt, David M.en
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.date.accessioned2014-03-14T20:21:28Zen
dc.date.adate1996-04-05en
dc.date.available2014-03-14T20:21:28Zen
dc.date.issued1996-04-05en
dc.date.rdate1996-04-05en
dc.date.sdate1998-07-21en
dc.description.abstractThis research focused on the characterization of organosilicone surfactants and their effects on sulfonylurea herbicide activity. The project included efficacy tests, rainfastness studies in the greenhouse, radiotracer studies on herbicide uptake, fluorescent dye studies on surface deposition, and various measurements of physico-chemical properties. In measuring physico-chemical properties, a logistic dose response relationship was found between adjuvant concentration and contact angle on parafilm. An AsymSigR relationship existed between adjuvant concentration and surface tension for all the adjuvants. The organosilicones, Silwet L-77, Silwet 408, and Sylgard 309, and Kinetic (a blend of an organosilicone with a nonionic surfactant) gave equilibrium surface tension values around 20 dyne/cm and showed great spreading ability on the foliage of velvetleaf. With the conventional adjuvants, Agri-Dex, methylated soybean oil, Rigo oil concentration, and X-77, and Dyne-Amic (a blend of an organosilicone with a crop oil concentrate), surface tension was rarely below 28 dyne/cm and spreading ability was limited on velvetleaf. In addition, the organosilicone surfactant and Kinetic also lowered dynamic surface tension, which may improve droplet retention on leaf surfaces. The differences in physico-chemical properties between Kinetic and Dyne-Amic confirmed that carefully electing a co-adjuvant for an organosilicone blend is critical to avoid antagonism with trisiloxane molecules and retain the unique physico-chemical properties of organosilicone in the blends. Studies involving structurally-related organosilicones showed that the end structure in the trisiloxane hydrophilic group has little or no effect on surface tension, contact angle, spread pattern, herbicide uptake and translocation, and efficacy of primisulfuron on velvetleaf. It may be suggested that there is not a strict requirement to purify the end structure during the synthesis process, which is time consuming and expensive. When 14C-primisulfuron was combined with organosilicones or the blends, the uptake of 14C at 1 or 2 h after herbicide application was significantly higher than when combined with conventional adjuvants in velvetleaf. In the greenhouse, organosilicone surfactants greatly increased the rainfastness of primisulfuron in velvetleaf. The effect was immediate and dramatic, even when simulated rainfall was applied 0.25 h after treatment. In addition, herbicide efficacy on marginally susceptible weed species, velvetleaf and barnyardgrass, was significantly increased. A very complicated relationship exists between herbicides and adjuvants. The enhancement effects of adjuvants are often herbicide specific, weed species specific, and even environment specific. No one type of adjuvant functions well in all circumstances. Therefore, there is a need to understand the properties and functions of each class of adjuvants and locate the 'right' niche for each individual adjuvant.en
dc.description.degreePh. D.en
dc.identifier.otheretd-214813359611541en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-214813359611541/en
dc.identifier.urihttp://hdl.handle.net/10919/30343en
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.relation.haspartjsun.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectuptakeen
dc.subjectprimisulfuronen
dc.subjectefficacyen
dc.subjectorganosiliconeen
dc.subjectadjuvanten
dc.subjectstatic surface tensionen
dc.subjectdynamic surface tensionen
dc.subjectcontact angleen
dc.subjectrainfastnessen
dc.titleCharacterization of Organosilicone Surfactants and Their Effects on Sulfonylurea Herbicide Activityen
dc.typeDissertationen
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en
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