Management of Salvinia (Sslvlnis Molests) in Australia
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Australian Weeds Vol 2(2) Summer 1962183 71 Management of salvinia (Sslvlnis molests) in lands (Figure D. The hi story and con Australia trol of the salvinia infestation at the dam has been recorded by Julian (1978). An estimated 18 ha ofsalvinia C. Max Finlayson and David S. Mitchell was present in 1977, spread over 40 km Centre for Irrigation Research, CSI RO , Griffith, New South Wales 2680 of shoreline. Much of this occurred in inlets and partly timbered areas where the plan ts were difficult to reach and therefore difficult to control. Initial Summary 1979; Finlayson, 198!) but no single control attempts by the Queensland satisfactory approach has yet emerged. Water Resources Commission using Since its introduction into Australia in A major factor in the spread and dis paraquat, diuron and 2,4-D (Table I) 1952 the aquatic fern salvinia has tribution of salvinia throughout Aust were not successful. Further details of caused serious problems, Despite con ralia is its rapid rate of growth under the herbicides used in these unsuccess siderable effort at control and eradica suitable conditions. Growth rates of ful attempts were not given. lion, no single satisfactory solution has 51 % day -I (I. 36 days doubling time) These earlier attempts were followed emerged, This paper revie ... the control in a sewage lagoon and 26% day-I by aerial spraying with AF 101 (kero methods tbat bave'Leen attempted in (2.67 days doubling time) in a lake sene. surfactant and diuron mixture) at Australia. Of the chemical' methods were recorded by Finlayson (198 D in 110 L ha- I to control the loosely dis used, spraying with paraquat, diu ron or north-western Queensland while Cary tributed salvinia. Such ae rial sprays (at AF 101 have been the most successful. and Weerts (1981) recorded rates of concentrations of 220 L ha- I) were The construction of floating booms or 32% day-I (2.2 days doubling time) not, however, successful against the nets has also shown a potential to res under culture conditions. The proven more tightly packed mats. Similar lack trict infestations and make eventual capacity of salvinia to grow rapidly un of success with AF 101 on tightly control easier. Damming of estuaries der Australian conditions raises special packed mats has been reported else usually increases the problem of salvinia problems in rel ation to its control. This where in Australia (Farrell, 1978, Fin control through restricting the inflow of paper outlines the results of a number layson, 1981), since for efTective con salt water and preventing the plants from of control techniques that have been trol this herbicide has to spread across being washed out to sea, whilst floods applied at various locations within the water surface from the point of ap can further spread existing infestations. Australia (Figure D. For a more plication and make contact with the The importance of developing an general account of the control of sal plants (OiatlofT el aI. , 1979; Finlayson, efficient and integrated control pro vinia the reader should consult Harley 198 D. When the mat formation s were gramme before the infestation becomes and Mitchell (198!). broken up with motor boats before well established is of paramount impor spraying with 250 L ha- 1 AF 101 the tance, As part of this approach, alterna Tinaroo Falls Dam, Queensland density of salvinia was reduced by 80 lives to chemical control should be The Tinaroo Falls Dam stores water to to 85 %, though a second spraying was actively pursued. generate electricity and to supply irri necessary to control the regrowth from gation water to the Atherton Table- unaffected growing tips. Such regrowth Introduction Salvinia (Salvinia molesla Milchell) is an aq uatic fern of South American origin (Mitchell, 1973; Mitchell and Thomas, 1972) that has spread through out the tropics and subtropics (Mit chell, 1978). Since its recorded intro l ake Moondarra duction into Australia at Luddenham, Lake Julius _ • Ross NSW, in 1952 (Harley and Mitchell, 1981) salvinia has spread throughout • the country; particularly along the eas I tern seaboard (Figure D. It has caused' ~ problems in recreation areas, im poundments, irrigation systems and other inland waters (Farrell, 1978; Jul Perth (Canning River, ian, 1978; Finlayson and Mitchell , Gosnells, Kewdale) 198!) and has the potential to spread further and interfere with proposed de velopments such as the Burdekin • scheme (Finlayson and Mitchell, 198!). Much efTort has been directed to , . wards the control of salvinia both in other countries (Cook and Gut, 1971 ; Kam-wing and Furtado, 1977; Mit chell, 1979) and in Australia (Farrell, Figure 1 Distribution of salvin!a in Australia (adapted from Harley and Mitchell , 1981 ). Areas of general oc currence are shaded while isolated occurrences are indicated by triangles (garden ponds or aquaria) 1978; Mitchell, 1978; Diatloff el 01., or squares (field sig htings or herbarium specimens). 72 Australian Weeds 1/01. 2(2) Summer 1982/83 has been reported on a number of oc needs of Mount 1sa. Salvinia was first The addition of diuron to the spray casions when this herbicide has been observed in the lake in October 1975, mixture did not prevent the growth used and has been partly overcome by and its spread since that time has been of new shoots from the kerosene adding 0.5 kg ha- I diuron to the mix described by Farrell (1978) and Fin- affected plants although experimen ture (Farrell, 1978; Diatloff el al. , 1ayson (1981). Since manual removal tal evidence had previously pointed 1979; Finlayson, 1981). railed to limit the spread of salvinia a to the effectiveness of such treat Aerial applications were successful spraying programme using II L para ment (Diatloff el a/., 1979; Finlayson, over open water but boats and a hover quat in 5000 Lofwater ha- I was started 1981). Despite an initial reduction in craft were necessary to spray other in January 1976 (Table I). Despite the biomass the hovercraft treatment did areas, and the overall result of the expenditure of S88 000 this pro not deliver enough herbicide to contain spraying was to reduce the salvinia in gramme did not contain the salvinia or prevent regrowth of the salvinia. To festation to less than I ha. Although and was eventually stopped in Novem overcome this problem a helicopter the dam is not completely clear of sal ber 1976. In conjunction with the was used to deliver 51 000 L of the vinia, the managing authorities con paraquat spraying, a series of floating herbicide AF 100 (i.e. AF 10 I minus sider the problem is controllable (A. C. booms was used to restrict the spread the diuron) during October 1978. This Julian, pers. comm.). Occasional out of salvinia throughout the lake and, ex approach was more successful and the breaks still occur from material washed cept for times of high river flow , these biomass was reduced from 142 t ha-I in from farm dams but these are con were a success. to 41 t ha- I over 275 ha at a cost of trolled when noticed. Since the initial Throughout the remainder of 1977 SI8 000 compared to 550 000 for the control programme in 1977 no large very little was done to control the sal hovercraft programme (Finlayson, outbreaks have occurred and the vinia and it built up to an estimated 1981). AF 101 application has been con 141 t (fresh weight) ha- I covering an Spraying by helicopter was success sidered a success. area or about 200 ha (Finlayson, ful when used against large areas of 1981). In December 1977 spraying salvinia, but was not effective against I.Ake Moondarra, Mount iSll, with AF 101 from a hovercraft com smaller, isolated areas of weed. A tem Queensland menced and reduced the fresh weight porary management strategy of heli Lake Moondarra is the principal source biomass to 35 t ha- ' spread over 204 ha copter spraying with AF 100 at of water for the mining and domestic by February 1978 (Farrell, 1978). periodic intervals was therefore adop- Table 1 Summary of chemical control programmes used against salvinia Herbicide Active ingredients Rate of product Locality Common name Trade name AF 101 1.25 kg diuron in 20 L 3:2:55 110- 250 L ha - ' Tinaroo Falls Dam acetone:Caldec:kerosene Ross River Adelaide River 112 Lh. - I Lake Moondarra 1 AF 100 1 :45 Caldec:kerosene 112 L ha·- Lake Moondaua diquat Reglone 200g L 1 diquat dibromide monohydrate 5.5 L h. I Western Australia muron Diurex 80 800 g kg 1 diuron 4.9 kg h. Fitzroy River 1/ IOOc Tinaroo Falls Dam hexazinone Velpar 900 g kg - 1 hexazinone Georges River 1 2kgha - Western Australia 3 kg ha - 1 Lake Julius glyphosate Roundup 360 g L-I glyphosate Georges River paraquat Gramoxone 200 g L -I paraquat dichloride Ross River 5 L ha-1 Fitzroy River a Leslie Harrison Dam Georges River Ib 3 mL L-- Nhulunbuy llLha - 1 Lake Moondarra c 1/400 b Tinaroo Falls Dam 3 mL L - 1 Adelaide River Mo notox 378 g kg - I DSMA , 240 g kg-I Ross River diuron, 64 g kg- 1 2,4 - 0 sodium salt Duotox 480 g kg - I diuron, 30 g kg - 1 DSMA Ross River 2,4-D Lane 2,4-D 500 g kg - I 2, 4- D 1/200c Tinaroo Falls Dam b Tryquat 100 g L - 1 paraquat dichloride 3 mL L _I Nhulunbuy 50 g L - I diquat dibromide monohydrate - informalion not available • high volume spraying with 225 mL Gramo1{on e in 136l waler (approl.) ~ nile calcu lated per WItter volume not area • dilution ni le only given Australian Weeds Vol .