HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mt. Pleasant, J. Articles by Coble, H. D. Search for Related Content PubMed Articles by Mt. Pleasant, J. Articles by Coble, H. D. Agricola Articles by Mt. Pleasant, J. Articles by Coble, H. D.

Weed Population Dynamics and Weed Control in the Peruvian Amazon

Dep. Agronomy, Cornell Univ., Ithaca, NY 14853
Dep. Soil Sci., North Carolina State Univ.
Dep. Crop Sci., N.C. State Univ., Raleigh, NC 27695

^* Corresponding author.

In traditional slush-and-burn agriculture, forest fallow is a primary agent in weed control. Stable continuous-cropping systems could be expected to require a comprehensive program of weed management, probably including the use of herbicides. Weed control measures in a sequence of rice (Oryza sativa L.)-corn (Zea mays L.)-soybean (Glycine max L.)-rice-corn-soybean were studied for 2 yr in Yurimaguas, Peru, with the following objectives to: (i) identify weed species resistant to the herbicide program in a continuous cropping system, and (ii) develop effective weed management practices for intensively managed cropping systems in the humid tropics. First-crop weeds were 60% grass, 25% sedges, and 15% broadleaf weeds. The grass was composed of two species: large crabgrass [Digitaria sanguinalis (L.) Scop.] and goosegrass (Eleusine indica (L.) Gaertn]. Sixth-crop weed population was 80% grass, 13% broadleafs and 7% spreading dayflower (Commelina diffusa Burm. f.); and itchgrass (Rottboelia exaltata L.f.) comprised 85% of the grasses. Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl) acetamide] controlled crabgrass, goosegrass, and most broadleafs in corn and soybean; but it did not control itchgrass. Metolachlor alone resulted in a weed population that was 97% itchgrass in the sixth crop. Sethoxydim {2-[(1-ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-l-one}-plus bentazon [3-(1-methylethyl)-(1.H)-2,1,3-benzothiadiazin-4(3H)-one 2.2-dioxide] on soybean controlled grasses including itchgrass, but broadleaf weeds and dayflower increased. Propanil [N-(3,4-dichlorophenyl) propanamide]-plus-oxadiazon {3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethyl)-1,3,4-oxadiazol-2-(3H)-one} on rice resulted in a mixed grass population. Rice was more vulnerable to weed pressure than either corn or soybean and appears inappropriate for this high-input rotation because of the high cost of weed control.

Received for publication April 18, 1989.