The efficacy of selected herbicide-adjuvant mixtures for the control of Roundup Ready (glyphosate-resistant) volunteer maize

Ehlers, Hendrik Gerhardus Abraham (2019-12)

Thesis (MScAgric)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: Roundup Ready (glyphosate-resistant) volunteer maize is a common occurrence in any production system where maize is planted. Volunteer maize is a result of maize seeds or ears that escaped harvesting in the previous year or season. Clethodim, quizalofop-P-tefuryl and glufosinate-ammonium were applied in combination with five adjuvants in order to establish the most effective herbicide-adjuvant combination for each of the three herbicides. A surfactant, penetrant, humectant, salt adjuvant and drift control agent was combined with the three herbicides in various combinations. Necrosis, stunting and mortality was assessed to determine the efficacy of the herbicide-adjuvant combinations. Two trials were executed to investigate the efficacy of the herbicide-adjuvant combinations. The first was a deposition trial where the combinations were applied at four different water volumes to investigate the effect of water volume on the efficacy of the herbicide-adjuvant mixtures. The second was an efficacy trial where the combinations were applied at the water volume as prescribed by the product labels. The deposition and efficacy trials were duplicated at two trial sites. An increase in water volume generally led to an increase in efficacy. The penetrant and humectant proved most successful with quizalofop-P-tefuryl. The penetrant increased the efficacy of clethodim significantly whereas the salt adjuvant proved most successful to combine with glufosinate-ammonium.

AFRIKAANSE OPSOMMING: Roundup Ready (glifosaat weerstandbiedende) opslagmielies is ‘n algemene probleem in produksiestelsels waarin mielies geplant word. Opslagmielies is die gevolg van mieliekoppe of –saad wat nie in die vorige seisoen of jaar ingesamel is nie. Clethodim, quizalofop-P-tefuriel en glufosinaat ammonium is in kombinasie met vyf verskillende bymiddels op opslagmielies toegedien om vas te stel wat die mees doeltreffende onkruiddoder-bymiddel kombinasie is vir elk van die drie onkruiddoders. ‘n Benatter, penetreermiddel, herbenatter, soutbyvoegmiddel en neerslaghulpmiddel is in verskeie kombinasies met die onkruiddoders gemeng. Nekrose, verdwerging en mortaliteit is ge-evalueer om die doeltreffendheid van die onkruiddoder/bymiddel kombinasies te bepaal. Twee proewe is uitgevoer om die doeltreffendheid van die onkruiddoder/bymiddel kombinasies te ondersoek. Die eerste was ‘n bedekkingsvlaktoets waar die kombinasies teen vier verskillende watervolumes toegedien is om die effek van watervolume op die doeltreffendheid van die onkduiddoder/bymiddel mengsels te bepaal. Die tweede was ‘n doeltreffendheidstoets waar die kombinasies toegedien is teen die watervolume soos voorgeskryf op die etikette van die produkte. Die bedekkingsvlak- en doeltreffendheidstoetse is op twee lokaliteite herhaal. Toename in watervolume het oor die algemeen gelei tot verbeterde doeltreffendheid. Die penetreermiddel en herbenatter was die beste bymiddel met quizalofop-P-tefuriel. Die penetreermiddel het die doeltreffendheid van clethodim vebeter terwyl die soutbyvoegmiddel die beste bymiddel was om te gebruik saam met glufosinaat ammonium.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/106978
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