Numerous plant species are considered weeds in agronomic cropping systems. Weeds have many attributes undesirable to crop producers, not the least being the ability to reduce crop yields through competition for resources such as sunlight, water, nutrients, and space. Weeds also may harbor insects and provide a host for certain plant pathogens. Some weed species, such as wild garlic and eastern ...

The critical period for weed control (CPWC) is the period in the crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses. Field studies were conducted in 2005 and 2006 in the University of Birjand at the south east of Iran to determine CPWC of corn using a randomized complete block design with 14 treatments and four replications. The treatments consisted of ...

In order to determine the responses of morphological characteristics, yield and yield components of rapeseed (Brassica napus L.) to plant density and weed interference duration, a factorial experiment was conducted using a randomized complete block design with 3 replications at the Rice Research Institute of Iran (RRII) in Rasht, in the 2008 growing season. The factors comprised plant density a...

Harrowing is often used to reduce weed competition, generally using a constant intensity across a whole field. The efficacy of weed harrowing in wheat and barley can be optimized, if site-specific conditions of soil, weed infestation and crop growth stage are taken into account. This study aimed to develop and test an algorithm to automatically adjust the harrowing intensity by varying the tine...

Charles Darwin [1,2] handed us a picture of competition as a constructive process responsible for adaptation to the environment, as well as the evolution of striking sexual displays and weapons. Darwin believed that sexual competition promotes adaptation by helping to weed out poor-quality males from the breeding pool and bringing about assortative pairing between high-quality males and females.

weed's behaviors differ in a multiweed-crop competition system compare to a mono weed-crop competition system. the present investigation was carried out in mashhad, iran, to study the effect of weeds, which emerged naturally in a multi species community along side with melon, on quantitative and qualitative characteristics of the crop during 2007. thirty five plots were selected randomly in a g...