Nimal Chandrasena

Bangor University · School of Biological Sciences

The evidence of changes in the global climate being felt by all of the bio-physical environments on the Earth is undisputed. Well-established literature, some of which is summarized herein, shows that the climate change effects will modify agro-ecosystems, including the multiple interactions between crops and weeds. From the perspective of weed man...

There is a growing global demand in the dyes and pigments industry for naturally-occurring pigments as substitutes for chemically synthesized pigments. This is because of increasing concern about potential adverse health effects for those involved in dye and pigment production and concerns about environmental pollution that can result from dye indu...

In addition to the benefits weeds provide to natural enemies of pest insects, weedy taxa are emerging as a critical component that can support pollinators, which are crucial for world crops. Understanding the vital interactions between pollinators, weeds, and crops will enable both the scientific community and the public to appreciate the ecologica...

With or without humans colonizing species will always be present on earth and continue to play vital roles in stabilizing the earth's ecosystems damaged by the teeming humanity. Therefore, humans need to 'live with weeds' and utilize their colonizing power for beneficial uses. If people well understand the valuable ecological roles and biodiversity...

Executive Summary By implementing a multi-faceted Plan of Management, in partnership with both governmental and private stakeholders and regulatory agencies, Sydney Water has restored the ecology of the Botany Wetlands, an environmental icon of Sydney. In doing so, a significant contribution to the State’s environment has been made. The environmen...

Hewett Cottrell Watson, a British botanist and phyto-geographer, might rightfully be the first to apply the term 'alien' to denote 'foreign' species introduced to Britain, which successfully established at various locations in the isles with or without man's help. Botanists recognize Watson for his monumental work Cybele Britannica, written in four...

A sound knowledge of the history of Weed Science – is essential for us weed scientists to adapt to emerging challenges and paradigm shifts in our dealings with weeds. It is helpful to know how we got to where we are in Weed Science. This knowledge of history should include a good grasp of reflections and ideas of our founders, which defined the pat...

As I said previously (Chandrasena, 2019), the incessant slandering of colonizing plants (weeds) by some people is a critical issue for Weed Science. It has inhibited the emerging generation of weed scientists from appreciating the utilitarian values and other redeeming qualities of weeds, as well as their ecological roles. It also prevents weed res...

Marcel Proust, once said: “The real voyage of discovery consists not in seeking new lands but seeing with new eyes." I suggest we look at weeds in this way in this 21st Century. In this Editorial for the second issue of the new journal - Weeds - I reflect upon some ideas that have shaped our recent discourses on weeds. It seems to me that the emer...

In this Editorial for the first issue of the new journal - Weeds - I reflect upon why the Asian-Pacific Weed Science Society (APWSS) decided to launch a journal and why we decided to make it Open Access (OA). A journal publication is usually the principal means of recording achievement in science. It is also the most efficient way for scientists to...

The APWSS, born on 22 June 1967, is now 52 years old. It is now taking a major step forward by publishing a dedicated, weed science journal-Weeds. In this Special Editorial for the journal's inaugural issue, I am privileged to have the opportunity to reflect on the landmark events, which preceded the Society's birth. We were not born by accident; m...

This book has been a collective effort by 26 members of the International Parthenium Weed Network, which is an International network of expert volunteers devoted to creating awareness about the parthenium weed ( Parthenium hysterophorus ) threat, and to sharing information on how to reduce its adverse impacts upon agro-ecosystems, the environment a...

As long-term practitioners of managing weeds in varied circumstances, we notice the increasing trend towards bush-regeneration as a broad approach to weed management, particularly in NSW. Recent observations in the Sydney basin and other parts of NSW show that bush-regeneration has not achieved the desired weed control outcomes for major weed speci...

Asian-Pacific Weed Science Society 50th Anniversary Celebratory Volume Contributory Papers, Memories and Reflections

In 2017, after 50 years of existence, Asian Pacific Weed Science Society (APWSS) is celebrating its Golden Jubilee, as it holds its 26th Conference at Kyoto, Japan. The hosting of the Conference in Japan, one of the founding members and major contributors to Weed Science in the region, should not go unnoticed. In this 50th Anniversary Celebratory V...

Weed Management in Australia: An Overview and Prognosis Nimal R. Chandrasena1 and Stephen B. Johnson2 1Principal Ecologist, GHD Pty Ltd., Parramatta, NSW, Australia; 2050 2Weed Ecologist, NSW Department of Primary Industries, 1447 Forest Road, Orange, NSW, 2800, Australia Abstract. One Australian definition of a weed: “…a plant, which has, or has t...

Of Weeds and Men: Some Perspectives Nimal Chandrasena Principal Ecologist, GHD Pty Ltd., Parramatta, NSW, Australia Email: nimal.chandrasena@ghd.com Abstract The relationship between weeds and men is an old one; however, it is changing fast. Increasing public concerns about the impacts of overuse of herbicides and other destructive farming practice...

Some people, particularly in developed countries, have strong negative attitudes towards weeds, and a tendency to label potentially useful plant resources as invasive 'aliens', which are to be controlled at any cost. This undesirable attitude ignores the considerable evidence of beneficial uses of weed species to many societies, over a long period...

In tropical Sri Lanka, Water Hyacinth [Eichhornia crassipes (Mart.) Solms.] and Salvinia (Salvinia molesta D. S. Mitchell) continue to dominate eutrophic waterways in both rural and urban environments. In addition, several other highly invasive species have also recently become problems in waterways, and these include: Alligator Weed [Alternanthera...

Human activities, including expanded fossil fuel use and deforestation, have caused atmospheric CO2 to increase significantly from a preindustrial concentration of about 280 μL L-1 to a current estimate of about 370 μL L-1. Even if CO2 emissions are immediately scaled back, levels are expected to double sometime during this century. An increase in...

Submerged aquatic invaders are increasingly becoming troublesome in human-impacted waterways. Several species, like Egeria (Egeria densa Planch.), Hydrilla (Hydrilla verticillata (L.f.) Royle), Hornwort (Ceratophyllum demersum L.), Sago Pondweed (Potamogeton pectinasus L.) and Lagarosiphon (Lagarosiphon major (Ridley) Moss), often form dense stands...

Despite control efforts over five decades, Alligator Weed has expanded its invaded territory in Australia in both aquatic terrestrial habitats. A recent risk assessment demonstrated that large-scale re-infestations of creeks and river systems have occurred in the past ten or so years, due to inadequate management regimes in many areas. Deficiencies...

Alligator Weed is acknowledged as an aquatic invader that poses possibly the largest threat to Australian waterways and moist, terrestrial landscapes. Since the threat became evident in the late 1980s, control efforts to manage Alligator Weed using an integrated approach have been continuing. Despite considerable efforts, Alligator Weed has expande...

Human activities, including expanded fossil fuel use and deforestation, have caused atmospheric CO 2 to increase significantly from a pre-industrial concentration. Levels are expected to double sometime during this century, even if CO 2 emissions are immediately scaled back. An increase in CO 2 and other greenhouse gases could lead to an increase i...

This paper summarises decision support tools developed to assist in managing Bung Boraphet, the largest freshwater system in Thailand. The tools were: Water budget predictive model, Land-use analysis using satellite imagery, and a Database linked Geographic Information System. The water balance model provided the basis for examining different scen...

In this series of glasshouse experiments, several factors influencing the foliar activity of fluazifop-butyl, butyl-2-[4-(5-trifluoromethyl-2-pyridylox-y)phenoxy] propionate, against Elymus repens (L.) Gould (=Agropyron repens(L.) Beauv.) were investigated. The growth stage of the weed even up to about 16 weeks of age was not found to be a major fa...

Some aspects of the action of fluazifop‐butyl on the chlorophyll content, chloroplast functioning and chloroplast ultrastructure of Elymus repens are reported. Over a period of 0–12 days after spraying with 0.25 or 1.0 kg ha⁻¹ of the herbicide, chlorophyll a and b contents of this susceptible plant decreased, progressing from the youngest to the mo...

A series of glasshouse experiments was conducted to evaluate the activity of fluazifop‐butyl, butyl 2‐[4‐(5‐trifluoromethyl‐2‐pyridyloxy)phenoxy] propionate, against Elymus repens. Foliar applications of doses 0·25–1·0 kg ha⁻¹ consistently gave better control than did soil applications. The most obvious phytotoxic symptoms were chlorosis and necros...

Bung Boraphet is the largest freshwater wetland in Thailand. It is an important economic asset to the provincial economy as well as a significant national and international biodiversity resource. Pressure on traditional uses of this water resource, such as for fishing and rice agriculture, is intensifying, as more people settle on the floodplain. I...

Glyphosate is the most widely used herbicide in the world. Surfactants are well known to enhance its uptake, translocation and field performance. The interactions between glyphosate formulations and surfactants, however, are not simple and depend on factors which include leaf surface, droplet characteristics, differential wetting of leaves, adjuvan...

Ludwigia peruviana (Primrose Willow; Family: Onagraceae), a native of South America, with a wide geographical distribution in tropical climates, has become a significant aquatic weed in eastern Australia, mainly in the Sydney basin. A second species-Ludwigia longifolia (Long-leaf Willow Primrose), first recorded in 1991 as an escapee from nurseries...

1.In Australia, the carp Cyprinus carpio L. is regarded as a threat to the native fish and the aquatic environment. In recent years, Botany Wetlands, a significant coastal wetland in the Sydney region, has been invaded by the undesirable cyprinids, carp and goldfish (Carrasius auratus L.).2.In 1996 a cyprinid removal programme commenced at Botany W...

The potential of Ludwigia peruviana, a non-native plant, to become a significant aquatic weed in Australia has been apparent since 1971, when established populations were discovered in the Botany Wetlands in Sydney, owned and managed by the Sydney Water Corporation (SWC). In 1996, dense L. peruviana infestations covered an estimated 40% of the tota...

The overall management philosophy for the wetlands is to respond to dynamics inherent in wetland systems, recognize the interdependency of groundwater and surface water systems, cater for natural processes and change, and recognize the place of the Wetlands in an urban environment. By applying principles of diligent environmental management, the re...

Executive Summary Six methods currently available for determining peptide hepatotoxins (microcystins) were compared to assess their performance. This assessment was carried out on extracts of freeze-dried cyanobacterial material, and with some of the methods, the impact of the water matrix was also evaluated.The methods assessed comprised: • High p...

Capillary Electrophoresis (CE) is a relatively new, powerful analytical tool that combines many advantages of liquid chromatography (HPLC) with those of electrophoresis. CE-based analyses to quantify paralytic shellfish poisons (PSPs) and microcystins are attractive to the water industry, particularly to supplement HPLC methods, and provide a means...

In Australia, the tropical/subtropical cyanobacterium Cylindrospermopsis raciborskii forms substantial blooms in some drinking water supply reservoirs, rivers and recreational water bodies during the warmer months of the year. This paper describes the isolation, culture and toxicity characterisation of Cylindrospermopsis from a water bloom in a sma...

The effect of glyphosate [N‐(phosphonomethyl) glycine] applied as foliar sprays, on the shoot growth, regrowth from ‘crown’ and rhizome bud‐viability of perennial torpedograss (Panicum repens L.) was studied. In general, rates of 1.0–4.0 kg a.i./ha killed 80–100% of aerial shoots and suppressed 90–100% of regrowth from treated plants. Rates above 1...

A survey of rice-field weeds was carried out in the Districts of Ratnapura and ~urunegala during the 'Yala' and 'Maha' seasons of 1986. Two hundred and thirty four fields of the Ratnapura District and 196 fields of the Kurunegala District were sampled at a time when the rice was at heading t o flowering and farmers had carried out weeding or herbic...

The effects of intraspecific competition on the growth, development and resource‐allocation of Panicum repens was studied under greenhouse conditions. Evidence of severe intraspecific competition and adjustments to plant growth as a response to stress caused by competition, was seen from fairly early stages. An eight‐fold difference in initial plan...

One hundred and thirty six weed species, belonging to twenty nine plant families were recorded from rice weed surveys carried out in four major rice‐growing districts of the low country Wet Zone of Sri Lanka, during two consecutive ‘Yala’ seasons in 1984 and 1985. In terms of abundance and distribution Moncotyledon weeds of the Poaceae and Cyperace...

The growth and development of three selections of torpedograss (Panicum repens L.), collected from different geographical locations in Sri Lanka were studied in order to understand the general patterns of growth and allocation of resources to various component parts. In general, the ascendancy of the mother culm was short lived. The grass showed a...

Two rice-growing districts in the low-country Wet Zone were surveyed for the wced-flora in the rice-fields. A comprehensive list of the spccies, including grass, sedge and broad-leaved weeds found in the rice-fields surveyed, is presented. An estimation of the frequency of occurrence of the major weeds was made in order to evaluate the a1)untlance...

Submerged aquatic plants pose problems in Australian and New Zealand waterways for navigation, flood management, bank erosion, recreation and aesthetics. Among problematic species are: Lagarosiphon (Lagarosiphon major (Ridley) Moss), Egeria (Egeria densa Planch.), Hornwort (Ceratophyllum demersum L.) and Elodea (Elodea canadensis Michx.). These spe...

Alligator Weed, a major aquatic weed in Australia, poses a significant threat to waterways and properties. It has the potential to cause losses of millions of dollars from agricultural, tourism and extractive industries in a major river system in Sydney-the Hawkesbury-Nepean River catchment. The Sri Lankan community had mistakenly grown Alligator W...

Sydney Water provides drinking water and wastewater services to over four million people in Sydney. This case study addresses the difficulties and costs associated with the control of Alligator Weed at Botany Wetlands, which is a key natural resource owned by the Corporation. This pond system is ecologically significant, and historically important,...

Despite considerable efforts to arrest its spread, Alligator Weed (Alternanthera philoxeroides) has expanded territory in both aquatic and terrestrial habitats. Although much planning has been done, a review of the information available and institutional frameworks, points to deficient management efforts, with little integration of knowledge into m...

A number of submerged aquatic weeds have colonized Australian and New Zealand waterways, assisted mainly by human activities. Three of these species-Lagarosiphon (Lagarosiphon major (Ridley) Moss), Egeria (Egeria densa Planch.) and Hornwort (Ceratophyllum demersum L.) prefer clear water, where they form dense stands, out-competing native vegetation...