pg . 70
NQ DRY TROPICS WEED FREE
HARRISSA CACTUS
H . martinin , H . tortuosa and H . pomanensis syn . Cereus pomanensis
HARRISSA CACTUS
CACTUS
DESCRIPTION
This is a perennial multi branched cactus with stems that form tangled mats about . 5 high . Many branches lay flat and take root where they touch the ground .
Stems have 6 ribs with low , triangular humps . The humps have grey hairs at the base of some sharp spines .
Flowers are large funnel shaped white and pink-tinged . They open at night . They occur near the ends of the stem on a tube that is 12 to 15 centimetres long . It flowers during spring and summer .
Fruits are round , red balls up to 5 centimetres wide and have scattered bumps with hairs and spines .
Seeds are numerous , small and black . They are embedded in the white pulp of the fruit which splits open when ripe .
Habitat this shade tolerant cactus occurs in softwood country and is also found in open country under box and ironbark trees and in pine forests .
Weed characteristics are dense infestations that choke out pasture and injure stock .
Dispersal seeds are spread by birds and animals . It can also reproduce by stem sections taking root .
BIOSECURITY MATTER
Restricted . This species is Category 3 Restricted matter under Queensland Legislation .
HOW TO ACT
Foliar spraying with an approved herbicide or basal barking is effective on this weed . Ploughing out followed cropping can be effective . Two biological control agents have provided control in some areas . An integrated approach using mechanical , fire , chemical and biological control combined with pasture management is most effective .