Academic literature on the topic 'Leptospermum continentale'

Leptospermum myrsinoides and L. continentale (Myrtaceae) are andromonoecious. All flowers of these species are potentially bisexual in function and male flowers result when pistil development ceases after floral initiation. All male flowers possess vestigial pistils. The proportion of male flowers within three populations was recorded over three seasons. In both species, the proportion of male relative to bisexual flowers increased as the flowering season progressed. A strong relationship exists between flower sex and branch position, with bisexual flowers tending to occur on upper and outer positions on plants. Fruit set is not limited by pollination but by some other resource, possibly nutrients. Whilst andromonoecy sets the upper Limit of the number of fruit which may be formed, the number of fruit set on a plant is always less than the number of bisexual flowers. It is suggested that andromonoecy in L. myrsinoides and L. continentale is an evolutionary response to low resource availability allowing optimal resource allocation to reproduction in these species.

The reproductive biology and floral phenologies of co-occurring Leptospermum myrsinoides and L. continentale were investigated. Both species have similar floral structure and both are protandrous. Anther dehiscence is staggered over approximately 6 days and pollen viability remains high for at least 3 days. The styles of both species are short at anthesis but extend during the next 6 days to approximately the same height as the anthers. The stigmas of these species do not achieve maximum receptivity until at least 4 days after anthesis. Both species are self-compatible. At the three sites studied, L. myrsinoides and L. continentale have separate flowering times with L. myrsinoides always flowering first. Within populations of each species, plants reached first flower and peak flower in the same order in 1989 and 1990, implying genetic control over flowering time. It is suggested that protandry in these species enhances the likelihood of outcrossing and the staggered release of pollen coupled with the degree of overlap within flowering populations increases the number of potential mates available to each flower.

We provide a summary of two recent studies that investigated the role that three native insectary plants can play in promoting predatory arthropods, and thereby to enhance biological control of vineyard pests in Australia. Native plants are preferred as supplementary flora, as they are locally-adapted to Australia's climatic conditions. Stands of mature Bursaria spinosa, Leptospermum continentale and Rytidosperma ssp. located adjacent to, or in vineyards, in South Australia were sampled for arthropods in 2013/14. Grapevines were also sampled to explore relationships between each plant and associated arthropods using common diversity indices. Twenty seven thousand and ninety-one individual invertebrate specimens were collected, comprising 20 orders and 287 morphospecies. These were categorised into functional groups of predators, herbivores and other. Predatory arthropods dominated the diversity of morphospecies present on each plant. The richness of predator morphospecies across all plant types was nearly double the number found in association with grapevines. It may be possible to increase the functional diversity of predatory arthropods by more than 3x when either B. spinosa or L. continentale is present versus grapevines only, and increase the net number of predator morphospecies by around 27% when Rytidosperma ssp. are planted in combination with grapevines. The selected plants provide a suitable habitat to support diverse and functional populations of predatory arthropods. The opportunity to plant selected native insectary species could help wine grape growers save time and resources by producing fruit with lower pest incidence, while enhancing biodiversity associated with vineyards.

The effects of the fire retardant Phos-Chek D75R on species composition, survival and growth of eastern Australian heathland vegetation are described. Two sites in Victoria were selected, Victoria Valley in the Grampian Ranges and Marlo in East Gippsland. Both areas supported heathland vegetation that was long, unburnt and relatively undisturbed. Plots were subjected to single applications of increasing concentrations of retardant (0.5, 1.0 and 1.5 L fire retardant m−2) or no additional fire retardant (‘Control’ and ‘Water only’ treatments). A single application of Phos-Chek did not appear to significantly change species composition or projected foliage cover of the major life forms of native heathland vegetation. However, it did cause whole plant and shoot death of key species Allocasuarina paludosa, Banksia marginata, Leptospermum continentale and L. myrsinoides, and was observed to affect other species. The fertilising effect of the fire retardant generally increased shoot growth of the key species but did not significantly increase the overall height of these species. The application of fire retardant enhanced weed invasion, particularly when supplied at higher concentrations. A number of research recommendations are made from this preliminary investigation.

Abstract A large-scale column study was conducted to examine the sediment and nutrient removal performance of stormwater biofilters that contained layers of novel copper-zeolite filter media. The filters were exposed to stormwater under varied dosing frequency over 33 weeks and were assessed for their hydraulic performance and their efficiency in removing sediment and nutrients. The non-vegetated sand filters with layers of copper-zeolite media (SCu filters) achieved consistently good removal of total phosphorus (87%) despite the challenging dry-wet cycles, and the effluent concentration met a long-term irrigation guideline (0.05 mg/L). The same design achieved 51% removal of total nitrogen above the Australian runoff quality load reduction targets (45%). Incorporation of Leptospermum continentale into the copper-zeolite filters (LCCu-T) maintained the phosphorus removal (86%) and led to a slight increase in total nitrogen removal (57%). Both designs maintained good water permeability (200 mm/h at the end of the last wet period). Copper-zeolite played a mixed role in the system: enhancing nutrients removal through precipitation and ion exchange, maintaining high water permeability, limiting the advantages of vegetation on nutrient removal. Future studies should refine biofilter design and vegetation selection to augment the performance of copper-zeolite filters by integrating the advantages of vegetation on nutrient removal.

The significant impacts of the introduced plant pathogen Phytophthora cinnamomi on native Australian vegetation have been well documented, but there is less knowledge of long-term effects. We assessed long-term (26 years) disease progression and impacts on vegetation floristics and structure at a heathy woodland site in the Great Otway National Park, eastern section. Disease progressed dramatically between 1989 and 2005 and by 2015 only 0.08% of the site was non-diseased. There were significant declines in plant species richness and numbers of susceptible species; and increases in percentage cover of resistant sedges and grasses overall, and in cover of Leptospermum continentale (prickly tea-tree) in post-disease areas. There were significant declines of Xanthorrhoea australis (Austral grass-tree), a keystone species that contributes greatly to vegetation structure and fauna habitat. There is an urgent need to map the distribution of P. cinnamomi affected vegetation and identify floristically important non-diseased vegetation in the national park. It is imperative that quarantine of non-infested areas, phosphite application, track closures and vehicle wash-downs be implemented to reduce disease extension and protect the significant biodiversity of the region including species rich heathlands and nationally listed threatened plant and fauna species and their habitats.

This study investigated the role that native insectary plants can play in promoting predatory arthropods, and thereby to enhance biological control of vineyard pests in Australia. I also set out to clarify if light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) is the main lepidopteran pest of grapevines in vineyards. Economic damage is caused to grapevines each season by pest species and E. postvittana is considered the dominant insect pest in Australian vineyards. However, recent observations suggested that species of tortricids other than E. postvittana may also act as pests. I investigated which tortricids are present in local vineyards, and whether the diversity of tortricids varied significantly among vineyards. I used molecular methods to determine the species of tortricids present in the canopies of grapevines over two growing seasons. This study confirms that E. postvittana is the most common tortricid pest in South Australian vineyards. Acropolitis rudisana (Walker) (Lepidoptera: Tortricidae), lucerne leafroller, Merophyas divulsana (Walker) (Lepidoptera: Tortricidae), and cotton tipworm, Crocidosema plebejana (Zeller) (Lepidoptera: Tortricidae) are also present in grapevine canopies but have not been reported previously. I also sought to determine if three native candidate native insectary plants, Christmas bush, Bursaria spinosa (Cav.) (Apiales: Pittosporaceae), prickly tea-tree, Leptospermum continentale (Forst. and G.Forst) (Myrtales: Myrtaceae), and wallaby grasses, Rytidosperma ssp. (DC) (Poales: Poaceae) have the capacity to support populations of predatory arthropods throughout the year, and if they may also provide habitat for economically damaging vineyards pests. Surveys were conducted in Adelaide Hills, Barossa Valley and Eden Valley vineyards over a 12-month period. The data were analysed to answer the following questions. What is the biological and functional diversity associated with each plant species? What are the features of an effective, functional native insectary plant assemblage for use in and around vineyards? What is the level of similarity and dissimilarity between the arthropod faunas of each plant species? Each plant species was found to support diverse predator species, which should attack a range of other arthropod pests across their life stages. It may also be possible to increase the functional diversity of predatory arthropods by more than three times when B. spinosa or L. continentale is incorporated into a landscape containing vineyards. Rytidosperma ssp. provides valuable complementary habitat for predatory species other than those commonly found in association with the woody perennials. When Rytidosperma ssp. are included in a viii plant assemblage with each woody plant species, this could result in an average net increase in predator morphospecies richness of at least 27%. Species distribution modelling was used to examine the potential range of each plant species under different climatic conditions. The insectary plants are naturally adapted to all of the major wine growing regions within Australia. Vineyard managers are encouraged to explore the use of B. spinosa, L. continentale and Rytidosperma ssp. as insectary plants in their vineyards. This information could help wine grape growers to manage pests like LBAM, save time and money by producing grapes with lower pest incidence, while enhancing the biodiversity of their vineyards.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2019