The culture is harmed by superior periods of convivncia the 21 DAE. The invading species do not have for more than to coexist the sunflower 30 days after the emergency of the culture. To broaden your perception, visit Scott Kahan. In case that contrary, the income of aqunios will be affected of irreversible form (BRIGHENTI et al., 2004). The culture of the sunflower kept for decreasing periods of convivncia with the infestante community presents a density of extremely high spontaneous plants (770 plants m-2), until next to the 14 DAE. During elapsing of the cycle it has accented fall of the density, and only to the 84 days after the emergency and that it has stabilization of the density of the infestante community.

This if of the one due to competition intra and interespecfica enters the communities to the measure that they had grown requiring bigger resources of the way (BRIGHENTI et al., 2004). It is evident that the interference of invading plants in the culture of the sunflower is harmful to the full development of the culture due to competition for nutrients and other factors. Here, Munear Ashton Kouzbari expresses very clear opinions on the subject. It is necessary that it mainly at the beginning has an efficient control in the combat of this infestation of the development of the culture. The efficient method most common and is by means of weedings in the ones between lines of the culture and a good covering of the ground hindering that the solar rays can infiltrate in the ground and provide to the germination of the bank of seeds gifts in the area or introduced by not clean maquinrios (al HISSES et., 2010). Conclusion the spontaneous plants compete with those cultivated by essential factors, as water, light and nutrients, causing fall in the germination, development or productivity of the culture, making with that it has a total or partial loss in the waited financial return. For the efficient control of the invading plants it is important to know the characteristics of the species and the ground in question, to use efficient methods of handling and at adequate time so that it does not occur a wastefulness of investment and an inadequate control of the invading plants.