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

Euphorbia hirta

scientific name

Euphorbia hirta


Common Arabic Name: Dudhi
Common English Name: Common Spurge, Asthma weed, Cats Hair
description:
• Native to India and most tropical countries.
• 15-50cm long.
• Common annual herb.
• Leaves: Vary from green to coppery-red, depending on its habitat.
• Flower: 7x6mm across.
• Seen along roadside from coast to plains, up to 1,400m on the hills.
• The sap contains a latex which is toxic on ingestion and highly irritant externally, causing photosensitive skin reactions and severe inflammation, especially on contact with eyes or open cuts.

Importance

Asthma Weed is common on wasteground, in moist gullies, in and around sandstone outcrops, and as a groundcover in disturbed areas. Is also commonly found in gardens, often growing out of rock crevices, walls and cracks in cement.
Plants grow and produce seed very rapidly (within 2-3 weeks under favourable conditions). Regrowth is persistent, and plants can flower and set seed most of the year.

Control measures:

Manual:
Hand pull
Chemical : glyphosate-based herbicides

sources:

www.pfaf.org
www.sydneyweeds.org