WEEDS

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Weed Management

Parasitic plants are difficult to manage due to various adaptive biological or ecological factors . With continued use of chemical herbicides , parasitic plants develop resistance mechanisms , making further use ineffective . The herbicide effective for a particular weed may also affect desired plants (crops . In biological control , it is difficult to synchronize the life cycles of the biological agent and the parasitic plant . At the same time , it is difficult to use biological agents which cannot discriminate weeds from crops . In cases where the

br desired plant fails to either metabolize the herbicide or out-grow the chemical barrier , it could also be affected by the herbicide

Critical period of weed control (CWC ) is the stage of plant growth during which it must be kept free from weeds to avoid yield loss . The CWC for corn is between the 3-14 leaf stages . This is the period of foliage growth , and weed interference reduces the space available for leaves to develop (Hall , et al , 1992 . The weeds that infest corn during this period gap include pig weed , giant rag weed and wild mustard

Two factors are taken into consideration during herbicide application The first is the duration of weed control to avoid yield loss , and the second is the time span that weeds can stay in a crop before causing harm . This knowledge guides weed management in that residual herbicides which have long term side effects are avoided

Allelopathy is the effect that a plant can have upon another...