Herbicides and their application for the control of mimosa in the Northern Territory, Australia (original) (raw)
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Biological control of Mimosa pigra and its role in 21st century mimosa management
Northern Territory land managers, government agencies and community have some 40 years experience of living with, and trying to manage, mimosa. In that time, best practice has evolved and the importance of integrating a variety of techniques is now well recognized and demonstrated. Biological control of mimosa, Mimosa pigra L., commenced in 1979. The program included a comprehensive survey of mimosa's native range. Potential agents were identified based on their abundance and impact in the field and on a capacity for mass rearing or culturing. A number of the agents released have had an impact and others recently released show promise of doing so, others have not. This paper proposes that other countries considering mimosa management can benefit from the 23 years of experience developed in Australia. They can select an effective suite of agents, establish them quickly, and utilise a range of other proven techniques and application methods. They have the opportunity to implement cost-effective management of mimosa quickly and effectively.
Ecological studies to optimise the integrated management of the wetland weed, Mimosa pigra
1999
The tropical American shrub, Mimosa pigra L. (Mimosaceae) is now widespread throughout the world's tropical wetlands. In Australia, it forms impenetrable thickets over more than 800 km 2 of the Northern Territory (NT), greatly reducing biodiversity. It competes with pastures, hinders mustering and access to water. Biological control is a promising control strategy due to the cost of chemical and physical control exacerbated by difficult access to stands that can be protected from aerial spraying beneath Melaleuca swamp forests, and often flood for months. Nine insect and two fungal biological control agents have been released in Australia over the last sixteen years. However, it is too soon to tell if biological control will provide sufficient control, and alternative methods are currently needed. Physical and chemical measures can eradicate small infestations, although these often require sustained control for several years. Managing large stands is more difficult, and we believe an integrated approach combining biological control, aerial herbicide applications, mechanical control, fire and revegetation is required. To study the interactions between control strategies a large-scale integrated control experiment was established at Wagait, in the Finniss river catchment, NT, Australia (12º56'S, 130º33'E alt. c.20 m). This paper describes how treatments were applied, the aims of the experiment, and the measurement of mimosa population dynamics parameters to provide a scientific basis for the development of an integrated control strategy for mimosa.
Biological Control, 1998
The influence of host plant phenotype on the impact caused to Mimosa pigra L. (Mimosaceae) plants by the feeding activity of larvae of Carmenta mimosa Eichlin and Passoa (Lepidoptera, Sesiidae) and the relationship between plant phenotype (through plant quality) and larval development were investigated under controlled conditions. Plants grown under conditions of reduced light availability were most prone to the detrimental effects of the feeding activities of C. mimosa larvae. The relative growth rate (RGR) of most plant phenotypes could be reduced when infested with C. mimosa larvae compared to uninfested plants. Small plants infested with C. mimosa and grown under reduced light availability exhibited significant reductions in RGR sooner than large plants grown in full sun. The physical quality of stems was correlated with the severity of impact, i.e., whether stem breakage occurred. Little larval-induced mortality of plants was observed, suggesting that vascular tissues remained sufficiently intact to allow translocation. Systemic stem death arose through infection by secondary pathogens. Differences in biomass of infested versus uninfested plants of all phenotypes were associated with the loss of stems and to a lesser extent leaves. The phenotype of plants had a significant effect on the development of C. mimosa larvae. Larvae in stems of plants with good access to reserves of soil moisture reached more advanced stages of development sooner than did those in plants which were often water stressed. This response was mediated through the combined influence of availability and nutritional quality of food. The implications of these findings to the impact of this agent in the field and the factors which may significantly influence its population dynamics are discussed.
A risk assessment of the tropical wetland weed Mimosa pigra in northern Australia
2004
Information on the biology and management of mimosa, Mimosa pigra L., has been collated and analysed in a risk assessment in the regional context of northern Australia. The aim was to provide guidance for environmental managers and researchers to collate and assess relevant information to assist management decisions relating to areas at risk of invasion and consequences of invasion. The major wetland categories in northern Australia are briefly described and a summary of the effects of mimosa on native fauna, flora and socioeconomic factors is presented. The current and potential distribution of mimosa in northern Australia is discussed, along with factors influencing establishment, density and distribution. The prediction of the potential distribution compares annual rainfall zones with CLIMEX modelling, overlaid with potentially vulnerable wetlands and land tenure. These are discussed in the context of the current management of mimosa in northern Australia. Uncertainty and information gaps relating to the extent and effects of mimosa are also highlighted. An estimated 4.2 to 4.6 million ha of wetlands in northern Australia are under threat from mimosa, though the actual area of suitability within this range is unclear and dependent on further research. Resolving such uncertainty is seen as a priority task, as it will provide a stronger basis for strategic research and control activities.
Determining suitable methods for the control of Mimosa pigra in Tram Chim National Park, Vietnam
A series of field experiments was carried out in Tram Chim to test the effectiveness of various control methods. Stem cutting, burning and the combination of stem cutting and burning were not effective. Living mimosa plants were difficult to burn, and cut stems resprouted quickly after treatment. Fire triggered mimosa seed germination. Cutting stems at the beginning of the flood season was more effective in killing mature mimosa than cutting during the dry season. The herbicide metsulphuron was more effective on seedlings and young than on mature plants. It was concluded that no single method was successful on its own in eradicating mimosa in Tram Chim. We recommended a forceful eradication method that combines stem cutting, fire, flood and herbicides, each method targeting a specific growth stage of mimosa. The integrated eradication should be a part of a broader strategic mimosa management plan.
Distribution, biology and management of Mimosa pigra in Sri Lanka
Mimosa, Mimosa pigra L., was first reported in Sri Lanka in 1997. The species is mainly confined to the central and northwestern provinces of Sri Lanka. The plant has colonised along the river banks of the Mahaweli River, which is the main supplier of irrigation water to the agriculture-dominant dry zone of the country. Use of river sand for construction work was identified as a major method of seed dispersal, apart from seeds being transported with river water flow. GPS technology is currently being used for monitoring the extent of spread of this species. Mimosa seeds were 100% viable after four years of storage at room temperature (28±2°C) and also at 8°C. The onset of flowers was first observed at 12-14 weeks after planting. The initial growth of the weed was slow, but the height increased at a rate of 2.4-2.6 cm day-1 during the first 8-12 weeks. From 12 weeks, the stem dry weight of mimosa increased at a more rapid rate than the root dry weight. The relative growth rate (RGR) increased until onset of flowers and then decreased. The soil seed-bank density within the canopy diameter of the naturally grown mimosa plants varied from 2,336 to 46,410 seeds m-2. Glyphosate at the dosage of 1.44 kg active ingredient ha-1 effectively controlled mimosa seedlings less than six months old, when applied three times repeatedly at four-month intervals on the same set of seedlings. Mimosa seeds did not germinate in the presence of one-month old Panicum maximum Jacq. at a population density of 16 plants m-2. Awareness programs conducted for the communities in the infested areas have resulted in several community participatory activities to eradicate small patches of mimosa from the Central Province.
Adverse Effects of Mimosa Invisa Mart . Infestation on the Floral Biodiversity
2017
Mimosa invisa Mart. (Mimosaceae) is an alien invasive weed, spreading rapidly in all topographies of Kerala, especially in the open areas and pastures. Since its introduction to Kerala in 1964, it has emerged as a problem weed adversely affecting the biodiversity of the area of infestation. The heliophytic nature, high smothering index and allelopathic effects contribute to the adverse effects of the plant on the accompanying vegetation. Studies at the Kerala Agricultural University during 2002-2004 confirmed that the suppression of the native flora by M. invisa was more conspicuous on grass weeds (21%) compared to broad leaved weeds (11%). The smothering efficiency of M. invisa increased by 25 percent towards the third year of infestation in pastures, which is an indication of the competitive ability and aggressive nature of the plant. This study emphasises that adoption of proper control measures against M. invisa during the early years of infestation is necessary to contain the w...
Biological Control, 2010
Macaria pallidata (Warren) and Leuciris fimbriaria (Stoll) (Lepidoptera: Geometridae) are abundant and damaging defoliators of Mimosa pigra L. in the native range of the Neotropics. Both species were assessed for their suitability as biocontrol agents of M. pigra, a damaging invasive weed of northern Australia. Larvae feed on leaves of all ages. Adults are non-feeding, short-lived moths. Generation times are short and fecundity is high allowing rapid population increase. The host specificity of these species was tested using larval development tests on 70 test plant species. Development to adult of M. pallidata occurred on six species other than M. pigra. However, the survival rates were so low that these plants could not sustain a population of this insect species. The maximum survival rate was 1.1% compared to 64% on M. pigra. When the mean lifetime fecundity is considered, a survival rate of 1.1% is the minimum required for population maintenance in the absence of other mortality factors. Open-field trials in Mexico, although not comprehensive, support the conclusion that M. pallidata is specific to M. pigra. Development beyond first instar of L. fimbriaria did not occur on any species other than M. pigra and Mimosa asperata L. The number of eggs laid by M. pallidata was independent of plant phylogeny, but adults of L. fimbriaria laid more eggs on plants more closely related to M. pigra, indicating that not all Lepidoptera show indiscriminate oviposition choices in confined situations. Following the gaining of required permits, M. pallidata was released from 2002 and L. fimbriaria from 2004. Both have established. M. pallidata has been recovered in large numbers from most sites across areas of infestation of the invasive plant, but experiences extreme population fluctuations. L. fimbriaria has been found only at low levels. The rate of parasitism of M. pallidata was 5% with the tachinid fly Carcelia malayana Baranov being the most common parasite.