紫茎泽兰优秀PPT.pptx

Ageratina adenophora(syn.Eupatorium adenophorum)is a species of flowering plant in the daisy family known by many common names,including eupatory,sticky snakeroot,crofton weed,and Mexican devil.Crofton weed is an erect,perennial shrub with numerous chocolate-brown woody stems emanating from an underground crown and reaching a height of 12 m.It has broad,slightly crinkled,trowel-shaped,toothed leaves with chocolate-colored petioles.It produces white flowers in spring.Crofton weed and mistflower are sometimes mistaken for each other.Table 1 distinguishes between the two species.DescriptionIt is native to Mexico,but it is known in many other parts of the world as an introduced species and often a noxious weed.It has caused great economic loss in agriculture in southwestern China,and is threatening the native biodiversity there.It was first inadvertently introduced to Yunnan around 1940,and its rapid spread is due in part to its allelopathic competition with other plant species.It also a weed in Australia,where it was introduced to Sydney in 1904.It has spread along the coastline of New South Wales and southern Queensland.Ageratina adenophora has also spread in Hawaii and the mainland USA,where it is recognized as a weed in ten states of the South and Southwest.Elsewhere it is an invasive species in many tropical and subtropical countries,including northeastern India,Sri Lanka,Nigeria,Southeast Asia,New Zealand,the Pacific Islands,the Canary Islands,and South Africa.The plant can spread vegetatively,that is the stems can sprout roots and grow upon contact with earth.The seed is also carried by the wind or water and colonizes disturbed areas,such as fields and areas near human habitation,readily.Seed may also be transported on animals and in soil.Distribution(分布)and habitatIt spreads rapidlyMature Crofton weed plants can produce between 10 000 and 100 000 seeds per year.Seeds are very light(25 000 seeds/g)and are windborne over long distances to invade previously non-infested areas.The seeds require light to stimulate germination so that invasion commonly takes place on bare,disturbed sites and only rarely on heavily vegetated areas.Places where Crofton weed is commonly found include:land cleared but not revegetated(再生长，再植)with pasture(牧草地，牧场)roadsides and waste areasUngrazed(不放牧）small holdingsState forestsNational parksabandoned banana plantationsfencelines.（警戒线）Why it is a weedIt is poisonous to horsesHorses may preferentially graze the plant even when ample feed is available.Access to Crofton weed for as little as eight weeks can cause sickness.The first sign of Crofton weed poisoning is coughing,made more pronounced by exercise.If horses are not removed from infested areas,further lung and possible heart damage occurs,leading to shortness of breath even when at rest.Death from respiratory failure is the eventual result,with affected horses often suddenly collapsing and dying during work.Treatment of Crofton weed poisoning is unlikely to reverse the damage,so early detection of poisoning and removal from the weed infestation is essential.If you suspect poisoning,seek veterinary advice.Poisoned horses may never again be capable of work.It is possible that Crofton weed is at its most poisonous during or soon after flowering.Pollen inhalation could be a factor in poisoning.About harmapplicationIt is a weed of non-agricultural areasCrofton weed is an aggressive invader of public amenity land such as State forests,national parks and nature reserves,as well as public utility easements such as railway embankments.Crofton weed can be controlled using a combination of methods,in conjunction with pasture and grazing management practices,aimed at creating an unfavorable environment for weed invasion.Mechanical control Chemical controlGrazing managementBiological controlControl and management