PEST MANAGEMENT DECISION GUIDE: GREEN LIST Siam weed Chromolaena odorata Myanmar: bizat; taw-bizat; Vietnam: co hoi; yên-bach Prevention Monitoring Direct Control l Purchase certified crop seed and animal l Herbaceous to woody perennial herb; l Use a combination of methods to control the weed. Carry these out feed to reduce the chance of contamination forms dense bushes on the ground before the weed flowers or sets seed to prevent spread. l As seeds can travel on animals and about 2 m high; climber; becomes l Hand-pull seedlings and young plants. Repeat every 2-3 months machinery, do not allow animals into an woody when mature afterwards due to rapid regrowth affected area, limit machinery use in the l Leaves: Soft, green, hairy, roughly l Completely dig out root system by hand or by using machinery – this Siam weed flowers (Colin area and keep machinery clean to prevent triangular; margins have 1-5 teeth when will be easier if soil is wet. Repeat twice during the growing season. Wilson) spread mature (younger leaves have none); numerous small dots on underside; 5-14 l Cutting is only a short-term solution as weed will grow back from the l Keep crop healthy to maximize roots competitiveness - use optimal water and cm long, 2.5-8 cm broad fertilizer levels l Roots: Fibrous; shallow – do not l Burn weeds that have been pulled up or cut (if permitted in your country). If not destroyed, they can take root and grow l Plant competitive species such as Leucaena penetrate beyond 20-30 cm in most soils leucocephala, Tephrosia purpurea and l Flowerheads: White or pale blue-ish- l Biological controls that have shown effectiveness include, Brachiaria decumbens to surpress the weed lilac; appear fluffy; many Pareuchaetes pseudoinsulata, Cecidochares connexa, Actinote thalia pyrrha, Actinote anteas, Acalitus adoratus, Calycomyza eupatorivora, l Plant cover crops such as Pueraria l Leaf shape, flower colour and structure Pareuchaetes insulata and Lixus aemulus. See if these are available in Siam weed seed heads (Colin phaseoloides, Calopogonium mucunoides, are similar to that of Mikania species. Wilson) your country. Centrosema pubescens or Vigna l Look along waterways and transport unguiculata to prevent weed establishment l It is difficult to kill this weed with chemicals because of its many tubers routes. Seeds disperse via water, wind and roots from which it can regenerate, and its waxy leaves and spread animals and vehicles Siam weed leaves (Colin Wilson) Note: Pesticides may be available to control this pest. Please check with the Ministry of Agriculture in your country to find out which pesticides are registered in your country and the local restrictions for their use. CREATED/UPDATED: Mars 2017 LOSE LESS, FEED MORE PRODUCED BY: Plantwise Plantwise is a CABI-led global initiative www.plantwise.org.