Introduction Senecio madagascariensis Poiret (fireweed) is an short-lived or daisy-like annual herb with abundant branched stem that grows from 10 to 70 cm in height. Fireweed is native to Madagascar and Southern Africa and it was first introduced in the Hunter Valley in Australia by 1918 (Department of Agriculture and Fisheries QLD, 2017) and large spread and infest in Hawaii(USA), Japan, Columbia, Argentina, Australia, Argentina (Sindel et al., 1998). The habitat of Senecio madagascariensis commonly distribute in the pastures, woodlands, grasslands, bushland of suburb, roadsides, disturbed sites and place where in the warm temperate regions (Department of Agriculture and Fisheries NSW, 2016 ).
The presence of fireweed produce a kind of alkaloid Pyrrolizidine which would cause fireweed poisoning. This is significantly risky to the livestock as the symptoms of poisoning usually comes in the form of weight reduction or low milk production which can be caused by several other reasons (Gardner et al., 2006). Furthermore, Senecio madagascariensis has a powerful ability in reproductivity and transmission, approximately one million seed can be produced per hectare with light infestation of fireweed and fireweed seeds can be spread in short distances through wind, stock transport and it can also be spread as transport contaminants through hydroseeding and grass seeding (Department of Agriculture and Fisheries Fact sheet QLD, 2017). For the reasons mentioned above, Senecio madagascariensis has been listed on the Weed of National in Australia. Fireweed has extremely high adaptability as the roots and base can survive through the summer and continue to grow in the following seasons, this means all ages fireweed can be present throughout the year (Department of Agriculture and Fisheries NSW, 2016). As such, the management of fireweed Senecio madagascariensis Poiret requires a reasonable and practical method incorporate with integrated weed management strategies (IWM) to reduce the risks of fireweed. The control tactics have been implemented for fireweed in multiple locations in world range, these locations include Hawaii (America), Queensland(Australia) and New South Wales (Australia). This review aims to examine and compare the application and management of Senecio madagascariensis in Hawaii, Queensland and New South Wales.
The weaknesses, future problems and potential improvements of current integrated weed management strategy would be explored according to the climatic and geographical condition of each location. Methods A review of current exist literatures was undertaken to attain background information relating to the biological properties, distributions and impact of fireweed in Australia and Hawaii. A combination of the keywords were used in the Google and UQ library search engine: Senecio madagascariensis, fireweed, Madagascar ragwort, Asteraceae, Australia, Hawaii, herbicides, control, management, distribution. This gained access to reliable website such as government websites. This include Department of Agriculture and Fisheries QLD & NSW, Brisbane city council, Department of Agriculture Hawaii. To attain peer-reviewed journal articles on Senecio madagascariensis Poiret in different countries for comparing IWM strategies in different countries, the University of Queensland library search engine and search engine from previous websites were used. The following keywords were used for searching: fireweed poisoning, fireweed control, biological control, fireweed IWM, management of Senecio madagascariensis, QLD fireweed, control tactics of fireweed, Senecio madagascariensis. Regarding to lack of information of non-english countries such as Japan and Argentina, locations with reputable weed management and control tactics were chosen: Queensland, New south wales and Hawaii. Current exist reliable journal articles and factsheets were selected for supporting further discussion of weakness and improvements.
The IWM strategy for Hawaii was attained through journal articles from Thorne et al.,(2005), Gardner et al.,(2006), Ramadan et al.,(2010) and factsheet from Department of Agriculture Hawaii (2013). For Australia, information of integrated fireweed management strategies were attained through Queensland government and New south wales websites, management guide and factsheets, along with journal articles and report by Tsutsumi (2011), Sheppard et al.,(2011) and Radford & Cousens (2000). In addition, the Weed science PLNT3012 learning guide and course text book Australian weed management system were also used to gain basic knowledges of control tactics of invasive plants. 2 3 Result Senecio madagascariensis Descripition. S. madagascariensis is an annual or a short-lived perennial plant (Department of Agriculture and Fisheries QLD, 2017). Depending on conditions, plants can have different sizes and shapes, in ideal conditions (wet, humid and warm), fireweed can grow up to 50cm tall with abundant wide, long leaves and several branches and about a hundred flowers. In comparison with ideal condition growth, it may grow in 20cm or less in height with narrow leaves and no branches and few flowers when under dry and tough condition. The leaves normally present dark green with serrated edges, 2 to 6 cm in length. The flowers present light yellow with about 2cm in diameter, each of flowers can produce up to 100 seeds, which is similar to the native Senecia species (Sindel et al., 1998). Each seed is 1 to 3 mm in length, cylindrical in shape, surface of seed often downy therefore they are easy to attached to animal fur or dispersed through wind. With adequate rainfall that allows fireweed to grow, most seeds geminate during autumn and winter (March to June), which would usually take 6 to 10 weeks depending on capacity of precipitation. Some of seeds died in the late spring and leave the taproot which is a shallow branched fibrous root that allow plants to move along with the wind (Department of Agriculture and Fisheries NSW, 2016). Fireweed have good adaptability, according to the research from Tsutsumi (2011), the most suitable mean temperature range for fireweed distribute in the warm region was between 23.5°C and 27°C, however, the most suitable mean temperature range for those lived in cold region was between -1.7°C and 4.8°C.
If grazed with S. madagascariensis over a long period, it would cause irreversible damage to the liver and have potential cause sudden death of livestock (Biosecurity Queensland, 2010). In Queensland, S. madagascariensis has been set as class 2 pest as this kind of pest has already colonised comparatively large areas of Queensland and caused so serious impact that government have to take it under control to stop its further development (Sindel et al., 1998). Figure 2: Distribution of S. madagascariensis in New South Wales by 2010 New South Wales. The S. madagascariensis is a serious pasture weed in New South Wales, according to the result of farms surveys from Sindel and Michael (1988), almost 90% of farms have been detected fireweed infestation within 8 regions. By 2010, fireweed has widespread to majority of eastern coast regions in New South Wales, this including Eden, Nowra, Newcastle, Port Macquarie, Grafton and isolated localised regions such as Dubbo, Albury (Department of Primary Industries, 2010) (Figure 2). The growth condition of S. madagascariensis is not limited by either fertility level or soil types (Sindel & Michael, 1992). Due to the large inventorof seedbank of fireweed, it can easily take over the heavily grazed pasture as in the dry summer the density of pasture population would decrease and indirectly result in an infestation of fireweed (Sindel & Michael, 1988).
As previous mentioned, the toxicity of S. madagascariensis would result in the reduction of agricultural production output, this directly causes the economic loss of 2 million Australian dollars as more money need to put on the management of fireweed meanwhile the incomes from commodities reduced (Department of Primary Industries, 2016). In addition, if fireweed was fed to livestock it could also result in the decrease of growth rate, chronic scouring. However, sheep and goats are more inclined to be fed by fireweed than other livestock, and they are more tolerant to pyrrolizidine alkaloids (NSW Department of Primary Industries, 2016). Hawaii. S. madagascariensis population localised in Hawaii are believed to have derived from Australia shipments. Fire weed was first introduced to Hawaii in the early 1980s, it rapidly infests the roadside and pasture on the islands of Hawaii from Kohala all the way up to Kahuä Ranch, then widespread on Waimea and stablished in Kona (Motooka et al., 2004).
Due to the invasiveness of fireweed, now it can be easily found on the walkway or pastures in Honoka’a, Maui, Ulupalakua, Kula, Makawao, Pukalani, Ha‘ikü, and Waihe’e (Motooka et al., 2004). The toxicity caused by pyrrolizidine alkaloids of fireweed result in illness, slow growth and liver disease or even death of livestock, moreover, pyrrolizidine alkaloid could also pose a risk on human diet, according to research result from Colegate et al. (2005) the honey and pollen product can potentially contaminate by the fireweed. Reasons mentioned above make fireweed on the eradication list of Hawaii department of agriculture annual report (2006).