Paul Barber

Over the years, we have conducted surveys, carried out monitoring, diagnosed health disorders, and treated a wide range of vegetation species throughout golf courses, parks, gardens and reserves in Australia and south-east Asia. Although vegetation within these growing environments can face similar challenges in both regions, there are many differences, including the vegetation species, pests and pathogens, climate, soil type, application of chemicals, type of management. The focus of this paper will be mainly on managing trees in Australia.

Perth, the capital city of Western Australia, is situated on a river with numerous bays. The peri‐urban environment extends along the coast for 100 km north and south of the city. Within the region is a fragmented landscape of suburbs, parks and remnant woodlands. The Eucalyptus gomphocephala woodland south of Perth is classified within the peri‐urban environment. Numerous Phytophthora species have been isolated from dead and dying endemic trees. The most frequently isolated species is P. multivora (65%), followed by P. aff. arenaria (21%); P. palmivora, P. syringae, P. inundata, P. aff. humicola, P. nicotianae and P. sp. ohioensis have also been isolated, although rarely. P. multivora and P. aff. arenaria have both been isolated from dying E. marginata (jarrah), E. gomphocephala (tuart), Corymbia calophylla (marri), C. ficifolia (red flowering gum) and Agonis flexuosa (WA peppermint). While P. multivora is commonly encountered in less impacted ecosystems, the other species found in the periurban environment (P. inundata and P. nicotianae) are rarely or never isolated. In the riparian ecosystem, P. aff. humicola has been isolated from dying Casuarina obesa. The knowledge about the impact of these species on our remnant trees is lacking. Further research is required on the origin, pathogenicity and control of these species to deliver effective management strategies.

Surveys of nurseries and plantations of Eucalyptus species were conducted within Lao PDR in 2009. A range of pathogens were isolated including species within Phytophthora, Pythium, Fusarium, Colletotrichum, Neofusicoccum, Lasiodiplodia, Pilidiella, Calonectria, Cryptosporiopsis, Corticium and Teratosphaeria. Some diseases caused significant defoliation and loss of stock within nurseries and plantations. The presence of these diseases in combination with a changing climate poses many challenges for the future sustainable and profitable management of plantations in Lao PDR.

Stem injections with phosphite liquid protect B. grandis and E. marginata from P. cinnamomi for at least four years . However, stem injection of phosphite is labour intensive and requires training, specialised equipment, and the mixing of chemicals. The recent development of soluble phosphite implants which can be quickly inserted into stems, overcomes the need for training and the use of specialised equipment. Systemic nutrient implants and injections have been effectively used to correct nutrient deficiencies in ornamental and horticultural plants and can help increase tree vigour to pests and pathogen attack. However, soluble implants of phosphite and nutrients have never been trialled for the control of Phytophthora. This study aimed to determine if liquid phosphite, soluble implants of phosphite alone, or combinations of macro and micro nutrients within implants inserted into the trunks of the trees could control lesion development caused by P. cinnamomi. In B. grandis and E. marginata, phosphite liquid and soluble phosphite implants significantly reduced lesion length compared to the control and application of nutrient implants. In B. grandis and E. marginata, nutrient implants reduced significantly the average lesion length compared to the control. Results show that both phosphite liquid and implants are effective at controlling lesion extension in B. grandis and E. marginata, caused by P. cinnamomi. Stem treatment with soluble phosphite implants will facilitate the rapid treatment of trees, and control of P. cinnamomi, in diseased areas. In addition, the uptake is passive, there is likely less damage to internal stem tissues, and less risk from phytotoxicity due to slow release of the phosphite compared to the liquid treatments.

In Western Australia there are a number of substantial declines and deaths across a number of forest and woodland tree species. These include Eucalyptus marginata, E. gomphocephela (tuart), E. wandoo (wandoo), E. rudis (swamp gum), Agonis flexuosa (peppermint) and Corymbia calophylla (marri). There are many theories put forward as to the reasons for these declines including: (i) global climate change; (ii) habitat loss and fragmentation; (iii) changes in land management, e.g. the absence of planned fire, damage from wildfires, and past timber harvesting and grazing; (iv) weeds, pests and diseases; (v) salinity; (vi) changes in hydrology; (vii) poorly developed links between research and management; and (viii) sub‐optimal management policies and strategies at Local and State Government levels. The Centre is made up of three core research organisations, 27 collaborating industry partners and seven collaborating international and national institutions. An overview of these declines, the possible causes, their implications to ecosystem function and health and the different research and adaptive management approaches that are in place to understand and mitigate these declines will be discussed.

Remote sensing of vegetation condition using high resolution digital multispectral imagery (DMSI) is an option for land managers interested in quantifying the distribution and extent of dieback in native forest. Crown condition is assessed as reference to the physical structure and foliage (i.e. density, transparency, extent and in-crown distribution) of a tree crown. At 20 sites in the Yalgorup National Park, Western Australia, a total of 80 (Eucalyptus gomphecephala) crowns are assessed both in-situ and using 2 acquisitions (2008 and 2010) of airborne DMSI. Each tree was assessed using four crown-condition indices: Crown Density, Foliage transparency, and the Crown Dieback Ratio and Epicormic Index. DMSI data is trained against canopy condition assessment data from 2008, crown condition is predicted using only spectral data. Comparison of DMSI derived Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and a novel Red Edge Extrema Index (REEI) suggests the REEI is more suited to classification applications of this type.

Corymbia ficifolia is a widely planted amenity tree worldwide. Recently, the species has been observed to be in decline in urban environments. This study investigated the causes of the decline in 246 trees in roadsides/median islands, parks, streets within residential areas in five urban areas in the City of Melville, 77 trees on the Murdoch University campus, and 82 trees in other urban areas and in its natural habitat in south‐western Australia. Tree diameter, height, and canopy/crown densities ranged from 5.5‐104.1 cm, 2.4‐18 m and 5‐100%, respectively. Most adult trees in urban areas suffered from canker disease caused by Quambalaria coyrecup which was commonly associated with branch flagging and dieback. No canker symptoms were found in natural stands of C. ficifolia. Occurrence of canker, dieback, flagging, and foliar diseases across all sites ranged from 0‐80%; 26.6‐80%; 4.7‐57.1%; and 29.2‐100%, respectively. Foliar symptoms caused by biotic and abiotic causal agents were also present. Whilst leaf disease is widespread, stem cankers are of major concern in larger trees. The health and structural condition of trees were scored and correlation among tree parameters with disease presence was assessed. Some diseases were common on C. ficifolia at a particular plant growth stage or in particular areas. The research indicates that disease problems in urban C. ficifolia trees are common and that more than one causal agent is responsible.

The Ludlow Tuart Forest is the only remaining tall tuart forest in the world and one of the rarest ecosystems on earth. Tuart forests are of immense value for conserving biodiversity and protecting ecosystem function, as well as providing important cultural, social and economic values. However, these areas have been impacted upon by various disturbances including logging, grazing, clearing and weed and pathogen invasion, which have resulted in changes in vegetation structure and composition. This is concerning to scientists, land managers and the public and has resulted in a growing desire to develop techniques to restore these forests. This study investigated techniques for establishing tuart forest species in degraded tuart forests, including: the creation of ashbeds; and the addition of nutrients, chelating agents and water sources. Restoration trials were undertaken with the assistance from a number of community-based programs aimed to facilitate participation in a number of phases of the restoration process. These included provenance seed collection, planting and monitoring. Trials indicated that creation of conditions that mimic natural disturbances has a positive influence on seedling survival and growth. Significant levels of survival and growth can also be produced through the use of plant treatments such as specific types of fertilisers and chelating agents. This study has shown that together with a range of plant and site treatments community engagement can be successfully captured to assist in the establishment and on-going monitoring of restoration trials. These types of trials will drive continued improvement of restoration techniques for degraded forests.