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The Horticulturist as Expert Witness


Professor Stefan Buczacki BSc, DPhil (Oxon), Hon DUniv, C Biol, FSB, FCIHort, ARPS, VMM, FLS. For over thirty years Professor Buczacki has worked as an expert witness successfully assisting clients, their lawyers and insurers under Civil and Criminal Rules guidelines in the fields of botany, commercial and domestic horticulture, mycology, algology and plant pathology. He is able to advise and gives evidence in all relevant areas including commercial insurance claims, personal accident, public liability, identifications and valuations.

If in your mind horticulture equates to gardening and conjures up images of lawn mowing, window boxes, Gertrude Jekyll and the Chelsea Flower Show, think again. Horticulture and the botany that lies behind it is represented by an industry worth many billions of pounds annually.

Even the UK garden retail market that caters principally for the amateur grower is worth around £5 billion. And where there is money, there is the potential for the loss of money, dispute over the cause of the loss, the involvement of insurance companies and lawyers; and the need for an expert.

I first became aware of this over thirty years ago when I left my full time post in horticultural research to become self-employed and was almost immediately approached to advise on a complex case concerning the origin of a plant disease problem on which I had just spent some years studying. The cause was a soil-inhabiting organism and numerous batches of commercial potting compost appeared to be contaminated. After a painstaking investigation involving visits to peat producers in Yorkshire and Ireland, I was eventually able to trace the source of the contamination to weeds growing on the bog where the peat used in the compost originated.

Finding the causes of crop losses such as this are my commonest type of case but my background, not only in horticulture and plant pathology but also in botany/mycology and forestry, in both of which I have degrees, has resulted in an increasing number of increasingly varied cases coming my way from the UK and beyond. With few exceptions, if there is litigation or the threat of litigation and plants or fungi are involved, I can usually assist.

Almost always, as in that first instruction, my work is in 'cold cases'; in trying to elucidate the causes of problems that occurred some years, sometimes many years previously. And almost invariably, I have to feed off scraps of evidence in trying to reconstruct the events. Take for example a fairly typical case involving a multi-million pound loss of a field crop and the need to discover who and what was responsible. Did anyone take the care to produce a detailed photographic record at the time, to collect and deep freeze plant samples for possible later analysis or map the pattern of diseased plants in the fields? No, of course not; and the absence of samples and good photographs is often my most significant difficulty. And in my experience – for I work in criminal as well as civil cases – police photographs, and above all police photographs taken at night, are the least helpful of all.

In my hugely varied career, I have proved that the mysterious death of trees in a large garden could not have been due to malicious poisoning by a neighbour as the owner suggested; I have demonstrated the growth rate of shrubs on the central reservation of a dual carriageway over a period of many years to show how much they may have obscured a pedestrian's view and contributed to a serious personal injury claim; I have valued horticultural material allegedly stolen from an employer; I have shown the inadequacy of the police's identification of alleged cannabis plants; and I have identified the green slime on which a claimant slipped in a rugby stadium and gave my opinion on whether the stadium's cleaning process should have removed it. The latter case demonstrated just how far forensic botany can take you because the rugby club claimed the stadium had been cleaned according to the directions of the cleansing chemical manufacturers two weeks before the start of the season; hence the cleansing should have been effective. But they forgot to say that the 'season' in fact began with a series of pre-season friendlies so the length of time involved was far greater and the efficacy of the cleansing would by then have been significantly reduced.

In many instances, the analysis needs to be genuinely forensic and there are numerous questions I must answer. Take a major commercial crop loss for instance. First, what are the symptoms on the plants and how do they vary individually? If the effects are manifest – as they often are – by lesions, where are the lesions situated – on the leaves, stems, buds and /or flowers? This is important because different pests and pathogens may affect different parts of the plants.

Do the symptoms vary from one plant variety to another which might indicate an inbuilt genetic differential susceptibility; or are they spread uniformly across all? Many pathogens and pests are peculiar to certain plant species and some, especially some pathogens, to certain varieties of certain species. Are any pests or pathogens present? Quite commonly pests move on to other plants after having caused the damage; or indeed the damage may be caused by larvae that have then metamorphosed into adults and hence disappeared. All this would help to pin-point the timing of the event.

How are any lesions dispersed – on a small group of plants or on all plants – which information may point to the focus of the initial infection? Or are the lesions confined to one side only of the plants in a manner than might indicate some correlation with the prevailing wind? Could pests or pathogens have been blown by the wind; or might the cause be non-pathological and perhaps be brought about by hail damage or the result of an air-borne pollutant? And if it was a pollutant, might it be the result of a genuine accident, the malfunction of machinery (in which case, by whose fault) or by carelessness – spraying a herbicide on a windy day for example? It is in fact in the area of herbicide damage that gardeners may be all too tempted to paint neighbouring farmers as bogey-men; or worse, may be tempted to 'try it on'. A recent case illustrated this perfectly.

Thoughts in a garden

An attractive, large and expensively created domestic garden was situated adjacent to farmland where a contractor had recently sprayed a cereal crop with selective herbicide. The garden owners made claim against the farmer for damage to their plants resulting from his contractor's negligence. The farmer's insurers approached me to nvestigate. There was certainly widespread damage to the garden plants as the garden owners were only too willing to show me and the damage was not confined to one type of plant; most were affected to some degree, evidence it might be thought of some common external factor because almost no plant disease affects more than a small number of related species.

But my experienced plant pathologist's eye told me a different story and the garden was in fact riven with a legion of different problems. Some were just possibly of herbicide origin but certainly none were typical of it. Laburnums throughout the garden had a peculiar symptom but my careful examination of the foliage went no way to confirming herbicide as the cause of damage. It was nonetheless not due to pest or disease attack, to wind damage or to any physiological disorder.

That plants should be selectively damaged at such distance from the presumed source of the chemical was also curious. A clematis growing on the boundary fence was ailing but this too was not entirely typical of herbicide injury and could have been caused by a number of other factors, and it was somewhat characteristic of clematis wilt, the commonest cause of clematis failure. Ornamental maples growing throughout the garden showed some signs of leaf tip browning and death, but I was unconvinced that chemical injury played any part in this and it was exactly the type of injury I would expect maples to display in so exposed a situation.

Then there were plants displaying signs of damage or distress certainly not caused in any way by herbicide. A large mature weeping willow close to the boundary of the garden displayed the severe leaf browning, spotting and twig cankers typical of willow anthracnose disease. Apple trees close to the boundary displayed leaf and fruit blotches caused by scab and the leaf disfigurement of mildew. A pear tree nearby showed some signs of both scab and pear leaf blister mite. Mature beech and other trees showed signs of leaf injury as a result of late frost and wind damage. And several herbaceous plants showed characteristic signs of various fungal leaf spotting diseases.

I concluded it was highly improbable herbicide played any part in any of the damage, the owners therefore failed in their attempt to have their garden re-stocked and no doubt went away somewhat chastened.

Another recent case involved a commercial field crop and highlighted an important aspect of disease pattern in the field and indicated the value of having photographs or plans at an early stage. A valuable vegetable crop had been affected by a fairly clearly defined and recognisable disease problem but its origin was disputed and I could have learned much from an accurate plan. If for instance the diseased plants were in lines or rows or could otherwise be related to the track and progress of the planting machine it would be strong evidence for the problem having originated on the transplants. If the pattern was in rows or lines but periodically stopped abruptly, this would be evidence that the origin may have lain in individual trays or batches of transplants. If the pattern of the diseased plants in the field however was not regularly geometric but in an irregular patch or patches unrelated to the path of the transplanting machine, it would suggest the cause of the problem was already present in the field soil. And of course in any or all of the above situations, if the pattern of disease was confined to certain varieties this would be highly indicative either of some environmental factor, like seed contamination, to which those particular varieties were subjected during their production; or of course, that there was significant difference between cultivars in their inherent susceptibility to the pathogens

Sometimes it is necessary to try and reconstruct the events on which a claim is based although the risk is in being hoist by one's own petard because it is difficult ever to reproduce everything exactly and any competent lawyer will be swift to point this out. It served me well however in a case involving imported Danish Christmas trees that although supposedly of a species that does not drop its needles, were in fact being returned with bare branches by disappointed customers. 'Not us' said the Danish growers, 'they were all right when they left Denmark'. I went to Denmark to check and felt they were correct but was then able to set up an experiment to reproduce the warehouse conditions in which the trees had been stored at the British port of entry. The fluctuating temperature and humidity reproduced exactly the needle drop effects and the importer's insurers paid up.

And although I suggested at the beginning that domestic gardening was not on the same monetary scale as commercial horticulture, large sums can nonetheless be involved. A few years ago, the owner of a magnificent country house had spent handsomely in engaging the finest designer to produce a garden to match; but had employed contractors to execute the design whose work fell abysmally short of the standard of execution needed; and then charged around a quarter of a million pounds for their efforts.

I was instructed by the client's lawyers to assess the quality of the work and the validity of the charges. I spent two days going over their workmanship with a fine tooth comb and produced a 10,000 word report detailing its multiplicity of shortcomings. I also made enquiry of the plant nurseries throughout Europe from where the plants had been obtained, compared the prices with those of comparable nurseries in the UK and with the charges made to the client and hence revealed gross over-charging. Eventually I was able so systematically to dismantle their invoice that the charges were reduced almost to nought; and I learned later that the firm had gone into liquidation. An expert's opinion can have far reaching consequences. ?