Determination of the critical period of weed control in corn using a thermal basis

Field studies were conducted over 3 years in southeast Buenos Aires, Argentina, to determine the critical period of weed control in maize (Zea mays L.). The treatments consisted of two different periods of weed interference, a critical weed-free period, and a critical time of weed removal. The Gompertz and logistic equations were fitted to relative yields representing the critical weed-free and the critical time of weed removal, respectively. Accumulated thermal units were used to describe each period of weed-free or weed removal. The critical weed-free period and the critical time of weed removal ranged from 222 to 416 and 128 to 261 accumulated thermal units respectively, to prevent yield losses of 2.5%. Weed biomass proved to be inverse to the crop yield for all the years studied. When weeds competed with the crop from emergence, a large increase in weed biomass was achieved 10 days after crop emergence. However, few weed seedlings emerged and prospered after the 5-6 leaf maize stage (10-20 days after emergence).

Examination report on the City of Granger, Iowa for the period July 1, 2012 through June 30, 2013

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Examination report on the City of Collins, Iowa for the period July 1, 2012 through June 30, 2013

Examination report on the City of Collins, Iowa for the period July 1, 2012 through June 30, 2013

Report on a special investigation of Grange Township for the period January 1, 2006 through November 15, 2013

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Examination report on the City of Central City, Iowa for the period July 1, 2012 through June 30, 2013

Examination report on the City of Central City, Iowa for the period July 1, 2012 through June 30, 2013

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Examination report on the City of Riverdale, Iowa for the period July 1, 2012 through June 30, 2013

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Examination report on the City of State Center, Iowa for the period July 1, 2012 through June 30, 2013