Determining the critical period of weed competitionwith the cultivation of beans (Phaseolus vulgaris L.)

Abstract

The sustainable handling of weeds inside aneconomic cultivation of short cycle as the bean (Phaseolusvulgaris, L) in the tropic, it is extremely complex, for the highdiversity and quantity of accompanying weeds, reasons for thosewhich with the bloom of the chemical methods in the decade ofthe 70, the use of herbicides emergent pree was implementedalmost universally; however, this method has caused theestablishment of highly aggressive species, of difficult handlingand that finely it is necessary to go to the conventional methodsto be able to lower its populations. On the other hand, it has beendemonstrated, the ecological damage that you/they cause theclean cultivations of weeds when being eliminated the refuge ofinsects, since I lower those conditions, it breaks the balance in theagroecosystem, what facilitates the reproduction of the insectstunes to the cultivation, becoming organisms plague. Thedetermination of the critical period of competition between theweeds and the economic cultivation is the only efficient road toonly establish methods of weeds handling during the time thatthe cultivation requires it and this way to facilitate the coexistenceinterespecific economic weeds -crop. To achieve that objective, itwas carried out an investigation during two campaigns where itwas evaluated at random by means of a design of blocks, withtreatments to the 8, 16, 24, 32, 40, 48 and 54 days of the germinationwith and without weeds, and two witness, with and withouthandling during the whole cycle of the bean. The dominant weedsin the system, was Cyperus rotundus and Sorghum attributablehalepense to the chemical methods of handling precedents.In accordance with the carried out statistical analyses the criticalperiod of competition of the arvenses with the cultivation of thebean was in the period that lapses from 24 to 40 days after havinggerminated the cultivation, period during which the works ofhandling of the weeds cannot miss the cultivation, preferably inform mechanics, to guarantee high yields, and ecological balancein the productive system. Work before and after this period theyonly contribute to elevate the energy expenses and to unbalancethe agroecosystem.