Weeds as alternative hosts for Ageratum conyzoides

Weeds can act as alternative hosts of many important crop pathogens.Ageratum conyzoides is a common weed in Vietnam, growing within crops, in fallow areas between crops and alongside footpaths. It is an alternative host of several important pathogens and provides a source (reservoir) of inoculum of these pathogens to infect new crops. If this weed is present, the farmer can lose the benefit of crop rotation for controlling pathogens in the soil.Ageratum conyzoides is a host of Ralstonia solanacearum (which causes bacterial
wilt), root knot nematode and possibly aster yellows, which is a disease caused by a phytoplasma transmitted by leaf hopper vectors to susceptible crops such as asters,potatoes, carrots and strawberries