Determining the critical period for grass control in high-yielding cotton using Japanese millet as a mimic weed

Field studies were conducted over five seasons from 2004 to 2015 to determine the critical period for weed control (CPWC) in high-yielding, irrigated cotton using a competitive mimic grass weed, Japanese millet. Japanese millet was planted with or after cotton emergence at densities of 10, 20, 50, 1...

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Bibliographic Details
Published in:Weed technology 2020-04, Vol.34 (2), p.292-300
Main Authors: Charles, Graham W, Sindel, Brian M, Cowie, Annette L, Knox, Oliver G. G
Format: Article
Language:English
Subjects:
Agricultural production
Competition
Cotton
Crop growth
Crop yield
crop yield loss
Crops
Echinochloa crus-galli
Emergence
Experiments
Grasses
Herbicides
interference
Irrigation
Millet
Morphology
Seeds
threshold
weed biomass
Weed control
weed density
Weeds
Wheat
Winter
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Summary:Field studies were conducted over five seasons from 2004 to 2015 to determine the critical period for weed control (CPWC) in high-yielding, irrigated cotton using a competitive mimic grass weed, Japanese millet. Japanese millet was planted with or after cotton emergence at densities of 10, 20, 50, 100, and 200 plants m–2. Japanese millet was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Data were combined over years. Japanese millet competed strongly with cotton, with season-long interference resulting in an 84% reduction in cotton yield with 200 Japanese millet plants m–2. The data were fit to extended Gompertz and logistic curves including weed density as a covariate, allowing a dynamic CPWC to be estimated for densities of 10 to 200 Japanese millet plants m–2. Using a 1% yield-loss threshold, the CPWC commenced at 65 GDD, corresponding to 0 to 7 d after crop emergence (DAE), and ended at 803 GDD, 76 to 98 DAE with 10 Japanese millet plants m–2, and 975 GDD, 90 to 115 DAE with 200 Japanese millet plants m–2. These results highlight the high level of weed control required throughout the cropping season in high-yielding cotton to ensure crop losses do not exceed the cost of weed control. Nomenclature: Japanese millet, Echinochloa esculenta (A. Braun) H. Scholz ‘Shirohie'; cotton, Gossypium hirsutum L. GOSHI
ISSN:0890-037X
1550-2740
DOI:10.1017/wet.2019.113