Skip to main content
ARS Home » Research » Publications at this Location » Publication #98438
Title: EFFECT OF GLYPHOSATE APPLICATION TIMING ON SOIL WATER DEPLETION AND CRON DEVELOPMENT

Author
item PARKER, DANIEL - UNIV OF ILLINOIS
item SIMMONS, FREDERICK - UNIV OF ILLINOIS
item NAFZIGER, EMERSON - UNIV OF ILLINOIS
item WAX, LOYD

Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Corn hybrids have been genetically modified to be resistant to glyphosate. This herbicide has excellent safety to the crop, but provides no apparent soil residual activity. Our research was initiated to determine the effect of weed competition on corn growth and soil moisture, and to optimize glyphosate application timing. The field experiment was conducted in Urbana, Illinois, on a Flanagan silt loam with 4.0% organic matter and a pH of 6.2. Glyphosate was applied to weeds ranging from 5 to 50 cm in height. Acetochlor and atrazine tank mix was applied preemergence to the soil surface. We measured soil moisture, chlorosis, stunting, light interception, and crop yield. Soil moisture was depleted at a rate 2 to 3 fold higher early in the season compared with later. Younger weeds present later in the season, due to reinfestation, depleted soil moisture at a rate two fold greater than older weeds still present in the untreated check. More moisture was depleted late in the season when weeds were controlled at 5 cm compared with control at 10 cm. More depletion occurred mid-season where controlled at 15 cm Treatments where weeds were controlled at 5 cm and kept weed-free produced the highest yields. Allowing weeds to reinfest after the control at 5 cm reduced yields 32%. Controlling weeds at 15 and 22 cm reduced yields 13 and 28%, respectively, whereas allowing weeds to compete all season in the untreated control plots reduced corn yield 68%. The standard soil-applied treatment was equal to the best glyphosate treatments.