Centre for Aquatic Plant Management Annual Report Summary 2003

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					Centre for Aquatic Plant Management Annual Report Summary 2003
Introduction The Centre for Aquatic Plant Management is 40 years old this year, and this gives me the opportunity to reflect on previous achievements. The aquatic section of the Weeds Research organisation was set up by Dale Robson in 1963, he was head of the section until 1983 when it was moved to Long Ashton. During Dale’s tenure the unit developed Midstream, tested glyphosate on aquatic weeds and promoted the use of grass carp, all of which are still in use today except Midstream which was unceremoniously and unjustifiably removed by the EU. Pip Barrett became head of the Aquatic Weeds Research Unit when he and David Riddington set up a new unit after the closure of the WRO. The AWRU moved to Sonning and the current facility was opened in 1986. During Pip’s reign, the work on barley straw was refined and developed into a workable algal management technique. This technique is now the most widely used aquatic weed control method in the world, with perhaps 20-30 million applications of straw on a worldwide basis each year. He also pioneered early season control of emergent weeds to retain habitat and reduce flooding potential. The environmental aspect of aquatic weed control has been increasingly important in recent years, and many of the techniques we now advocate make environmental concerns as a priority. I took over in 1994 when MAFF decided that aquatic weed research was not their responsibility and withdrew core funding, resulting i Pip’s enforced early n retirement. The focus of the research has changed to management of invasive aquatic weeds and development of non-chemical methods of weed control. Many of the techniques that were developed carefully for targeted aquatic weed control have now been withdrawn by the manufacturers or by EU legislation, leaving us with expensive niche market controls, or general chemical controls that do not work on the intended target species. However, the challenge for research is to develop techniques that are economically viable, effective and environmentally benign. The changing nature of the weed flora, exacerbated by current and future climate change scenarios, will always remain a research opportunity. Despite this, during 2003, the Centre for Aquatic Plant Management has been under threat of closure again. Rothamsted have decided that the work of the Centre does not fit within the overall science strategy of the Institute and has therefore declined to accept
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further funding for the CAPM, despite the fact that subscribers have committed funds for a continued research programme. We have explored two possible options for a new home, Reading University, which was unfortunately not successful because of funding guarantees, and the Centre for Ecology and Hydrology, which at the time of writing is still undecided. There may be other options, but at the moment it seems likely that if it survives, the CAPM will u ndergo a radical change in the next 12-18 months. The need for a Centre for Aquatic Plant Management has been confirmed by representatives of all subscribing organisations, and whatever happens in the next few months, the need for up to date advice and support for operational and managerial staff will remain. It is not yet clear how this servic e would be provided in the absence of a CAPM, and it is very important that as much support is given the Centre in the future. The adage of not knowing what you have lost until it is gone is highly appropriate. Mechanical Control Mechanical control methods have continued to d evelop in strange directions this year, the use of suction dredging for removal of Azolla, suction dredging removal of duckweeds and various other innovations have meant that the traditional cut and collect type of control remain la rgely unaffected by technological development. There were a number of new boats on display at the ADA demo in the summer, but colour differences were all that separated the technology. The problem for manufacturers is that technology appropriate for aquatic weed control may not be appropriate for other weed control operations, making product development very expensive and probably not worth the effort of branching out in new directions. However, the development of small scale harvesters went against the trend in mechanical control, and it is hoped that other developments will follow, especially in the light of the increasing use of m echanical control methods. Duckweeds Duckweeds are extremely difficult to control, especially in large and or slow flowing situations. There are a number of reasons for this; it is impossible to remove every frond by mechanical means, small leaves of L. minuta do not clump together and sink with turbulence, chemical control usually is only short term, due to either recruitment from upstream, or avoidance of treatment in double

layers. It therefore appears that the only sensible method of controlling Duckweeds is by environmental manipulation or mechanical removal. Duckweeds should be controlled in winter. The reliance on vegetative propagation means that nay reduction in the overwintering biomass will reduce the growth next year. If points of entry can be blocked, combined with effective mechanical and manual removal of odd nits and pieces, then complete eradic ation is possible. Unfortunately it involves more effort and man hours making it expensive. We were unable to test any of the alternative products this year. Suction Dredging of Azolla. This was tested by British Waterways, and after several problems due to floating trainers, plastic bottles etc and getting the weed to the nozzle, the technique worked quite well. The Azolla was pumped off the top of the water into a container with a filter to remove water. The water was returned to the canal, and when the container was full, it was tipped out and transported away. This reduced the weight of weed to be removed by about 50-60%. Weight reductions in Lemna would expected to be of the order of 70-80%. With increases in the costs of disposal, and much waste being costed by the tonne, any reduction in weight will save on disposal costs. In areas where debris is minimal, this technique would offer an effective method of removal for most species of floating aquatic weed. Chemical Control Given the removal of many of the old faithful products as a consequence of the EU review process, rather than any hint of environmental impact, it would seem sensible to focus on developing products for aquatic use that are derived from existing active ingredients that have already passed through the hoops of the EU review. There are several requirements of a good aquatic herbicide, it should be non-persistent, should target only plants, be fast acting, have no non-target effects, be safe to handle, easy to apply, easy to calculate dose rates, and available in small (5L) containers. Two compounds that spring to mind are glyphosate and glufosinate ammonium. The only reason these
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are not used for submerged aquatic weed control is due to problems with the delivery method. If the compounds could be retained in a gel like formulation and delivered direct to the plant tissue, then perhaps effective submerged weed control could be achieved. Compounds would have to fairly quick acting, so enhancements to uptake of glyphosate may be necessary, but there is significant scope for development. The release of a new product, Midstream GSR is the only bit of good news this year. This is a 20% d ichlobenil formulation. It should not be confused with the diquat alginate product, Midstream, although it probably will be. This means that troublesome weeds like Broad leaved Pondweed and Fringed water Lily are now controllable again. Non-chemical control Barley straw As may of you know the future of barley straw as an effective algicide was threatened by the Biocides Directive and the UK Biocidal Product Regulations in 2003. It is quite unbelievable that a natural product that mimics the falling of leaf and stem litter into water should be controlled by a regulatory authority. Even more difficult to be lieve was the situation that barley straw could have been put into water to provide food for ducklings, to act as a physical barrier, and invertebrate shelter and food source, and refuge for fish, but could not be put into water to act as an algicide. The authorities were without a little box to tick as far as the complex action of straw in water was concerned so they threatened to ban the use of straw for algal control. However, since there are no regulations about putting straw into water for any of the other purposes, it was difficult for them to make a convincing case that the presence of straw in water was an actual threat to human health or the environment. I felt something had to be done to get over this i m mense piece of bureaucratic nonsense, so I wrote to the HSE setting out the main modes of action of barley straw, and identifying hydrogen peroxide as the active ingredient. The Biocidal Product Regulations require an active ingredient of any biocidal product to be identified. As we again all know this is controversial for straw, but hydrogen peroxide appears to be the one compound that is produced when straw is in water that has actually been demonstrated to have an effect at the concentrations measure around decomposing straw. The HSE rejected my first attempt to persuade them that hydrogen peroxide was the active

ingredient, and said that there was insufficient evidence to show that this was the case. Their argument also relied on the fact that I had been honest with them and provided a list of other modes of action, which apparently also caused confusion in the system as there is no tick box for more than one mode of action. This left the straw industry in a difficult position. The active ingredient had been identified, but the HSE did not accept the identification. My attitude was to ask the HSE to prove that it was not hydrogen peroxide, which I did not pursue, but was later advised by the European Commission that if we had forced the issue with them, the HSE would have been obliged to undertake tests to show that hydrogen peroxide was not produced by decomposing barley straw. A situation that nobody would have wanted given the costs of such an undertaking. I also sent the mode of action document to the Chairman of the Competent Authoritie s group for biocides for presentation at the 15th CA-meeting of representatives of Members States for the implementation of Directive 98/8/EC concerning the placing of biocidal products on the market held on 15/16th December. This group decides on decisions that national authorities have to implement as part of the regulations. The UK was represented by the HSE as the UK Competent Authority for the Directive. I attended the meeting on 16th December, with Tony Pain of Greenways, a manufacturer of barley straw products. The aim of attending the meeting was to obtain agreement that hydrogen peroxide was indeed the active ingredient for the purposes of the biocides directive. The meeting went very well. I presented the document to the meeting and fended off questions from the French and Germans about irrelevant issues. The chairman of the meeting had advised me that he wanted barley straw to go through without much further discussion, as he did not think that straw should be subject to the procedures set o for regulating ut chemical treatments. In the end the chairman stated that it was accepted by the meeting that hydrogen peroxide was indeed the active ingredient, and that barley straw could stay on the market. The advantage of using hydrogen peroxide as an active ingredient is that many other organisations have also registered hydrogen peroxide as an alg icide, so we only need to copy the relevant bits from other peoples’ dossiers, add a bit about the raw material,

and submit it to the HSE by the beginning of 2007. This is when hydrogen peroxide is being assessed as stage 3 of the Directive. The assessment will take about 3 years, and so if the use of hydrogen peroxide is agreed as part of the review, then barley straw products can remain on the market. The situation with barley straw extracts is not so favourable, and related to a decision made by the Pesticides Safety Directorate in about 1994. When the CAPM asked if straw was a pesticide we were i n formed that unprocessed raw materials were not considered as pesticides, but anything that was processed automatically came under the jurisdiction of the Plant Protection Products Regulations and the Control of Pesticide Regulations Use of Ultrasound the CAPM were asked to investigate the mode of action of ultrasound on algae. The following light micrograph pictures of Selenastrum were taken from algal samples exposed to ultrasound for 8 weeks. The pictures of Spirogyra were taken over a three week period form a tank experiment undertaken in controlled conditions in the glasshouse. The mode of action appears to be by disruption of the connections between the pla smalemma and the algal cell walls. This causes loss of membrane integrity, probable leakage of cytoplasm and a collapse of the cell into a dense brown mass. The cells remain buoyant for at least 4 weeks after exposure, al-5 though they are no longer viable. The first picture on the shows healthy Spirogyra, with cells full of cytoplasm, and the characteristic spiralling chloroplasts. The algae was sourced from a tank at the CAPM in Sonning and had been healthy for at least 5 years. The second picture was taken after only 14 days exposure to ultrasound. The cells have shrunk, with some forming dense circular brown agglomerations in the centre of the cell. There is some evidence of cytoplasm leakage from the cells, indicating further damage to the cell walls.

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28 day regrowth experiment, the chlorophyll concentration continued to increase from Day 1. However, the increase in the aquasonic treated Spirogyra was significantly less than in the control treatment. This indicates significant structural damage is associated with cell death in Spirogyra.
800 700 600 500 400 300 200 100 0 Day 0 Day 1 Day 7 Day 14 Day 21 Day28 Days

In a

The Macrophyte Assessment & Probability System (MAPS) is a new approach to the interpretation of
macrophyte communities. Although, still in the early stages of development it has already shown considerable potential using a TEST DATASET and a small sub-set of data from the Avon SAC. The ‘key components’ of the model are not new, but the use of Artificial Intelligence (AI) techniques for lotic macrophyte assessment and interpretation has not been undertaken before now. In the last decade there has been a steady growth in the application of AI techniques to environmental and ecosystem assessment (e.g. Macro-invertebrates, Fish, Flood forecasting,). This is due to the increased computing power of everyday PCs and the development of new algorithms and programs that enable data processing and analysis of multivariate datasets using neural networks. The approach taken with the model presented here largely follows the methods of Walley et al., (2002) and initial data exploration uses the MIRmax tool developed by the Centre for Intelligent Environmental Systems (CIES) Experiments with neural network systems that enable diagnosis of ecosystem health are also conducted. Even though the model is not complete, the comp onent modules have demonstrated great potential for making an assessment of ecosystem health (using m acrophytes). One of the key strengths of Artificial Intelligence techniques is that they are not only very good at pattern recognition, but they also handle uncertainty in a mathematically exact manner (e.g. BBNs). Thus, when dealing with the interpretation and assessment of highly dynamic ecosystems we are better equipped to evaluate the evidence and make a judgement of condition by using tools based upon AI methods. This work continues…

Biological Control During 2003, we have progressed the Development of biological control in the UK. The outline o four reasoning behind this is presented below, this is essentially the same as last year, but bears repeating. The loss of herbicides will present an increasingly cost effective perspective on biological control of UK native and non-native species. There are a number of countries that exploit Biological control to their advantage, but none of them in Europe. This position is becoming increasingly difficult to justify, and we must make sure that biological control is developed as a matter of urgency. There are a number of research questions that arise from the presence and apparent late summer activity of the Azolla weevil in the UK: • • • Why has the weevil not been more successful at controlling Azolla? What happens to the weevil over-winter? Can late summer development be brought forward to improve weed control?

We intend to address these questions with CABI Bioscience if funding is forthcoming. There is another potential biological control agent for this species, already used in Africa, a flea beetle, Pseudolampsis guttata, that should also be assessed in any research program. The possibility of a selective control agent for Floating Pennywort exists in the form of the Curculionid weevil Lixellus elongatus. It is reported to feed exclusively on Hydrocotyle species in preliminary laboratory tests. No pictures are available of this species. The CAPM and CABI are obviously very keen to follow up this initial work. Rapid development of biological control of aquatic weeds is essential in order to maintain the ability to manage weeds in difficult situations, such as SSSIs and areas where machinery cannot reach.
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Contact Details:
Centre for Aquatic Plant Management Broadmoor Lane, Sonning Reading, Berkshire RG4 6TH Tel: 0118 948 2782 Mobile: 07889 903203 Email: Web:

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