Common names Black jack,spanish needle,hairy beggar ticks, chepkotiwe(kalenjin) maceege (kikuyu)
Originated in tropical America.
Description
The plant is an erect annual herb 20-150cm tall.It reproduces by seeds,the stem is square,green with brown strips.It can be easily identified by the elongated fruits that bear hooked bristles that sticks themselves in people clothings and animals furs.
Ecological Requirements
- It is a hardy weed capabl of invading a vast range of habitats ranging from infrtile soil,moist soil,sand lime rock and dry soils.
- It can thrive in low to high altitudes upto 3600m above sea level
- Its capable of surving severe droughts i.e rainfall of 500mm-3500mm per annum.
- It does well in a wide range of tempreture i.e 15-45 degrees celcius.it can also tolerate frost.
- Its not fire tolerant but invades burnt areas faster.
Reproduction and Dispersal
- Bidens pilosa behaves as an annual weed but variety but b.pilosa var radiata behave as perenial.
- It bears a compelete flower therefore poliination is by cross and self polination
- One plant can reproduce upto 3000seeds which are highy fertile.The seeds can remain viable for 5-6 years.
- The seeds germinate in shallow soils i.e 1cm but seeds deep in the soil will not germinate but stays fertile for a very long time.
- The seeds are dispersed through in the fruits that attach themselves in the clothing and fur of animals.
- It can also be dispersed by wind,water and soil.
COMPETITIVE ABILITY OF BIDEN PILOSA
- It grows very fast than the actual crop
- It produces many seeds which remain viable for a vry long time upto 5years.
- It has allelopathic properties which disadvantages the main crop in nutrient and water uptake.
- It has big root biomass which easily out competes the main plant in nutrient and water uptake.
- The seeds remains viable for a very long time.
Environmental and Economic Impact
- It is a serious weed in many cropping systems where it reduces yield because of its fast growth and competitive abilities
- It is also a host and vector of various harmfull parasites such as root knot nematodes and tomato spotted wilt virus.
- It is a weed of open areas where dense stands reduces access to roads,trails,recreational areas and damage to pavements and walls.
- The fruit has burs which sticks themselves to people hence bringing a nuissance.same to birds and animals.
- It inceases cost of production because of frequent weeding.
Management
- The management of this weed will depend on severity of infestation,terrain,cost and availability of labour.
- It can be best controlled when they are still small,this will prevent them from establishing.
- Controlling before production of seeds will prevent its future generation.
- This weed can be controlled by 2 methods Physical and use of chemicals.
Physical methods
- Persistent mowing
- Hand pulling
- Through mulching i.e either plastic mulch or organic mulch.This will smother the growth of the weed.
- Hoeing will also prevent its infestation.
Chemical methods
Use herbicides which are selective and non selective depending if the land is cropped or fallow.
- Use AGROMINE 480SL If the weed has invaded maize,rice,wheat and barley.
- Use COMMANDER 240EC If the weed as invaded an onion farm.
- Use HOTLINE 450 SC If the weed is established in carrot and corriander farm.
- Use CLAMPDOWN 480SL This will be used in fallow lands where the weed has establish itself.Most preffered for land preparation.
