Jan 1, 2001
Organic NZ Magazine - January/February 2000.Report by Meriel Watts.
PESTICIDE USE IN NZ - THE MAF PESTICIDE REPORT
It’s a good sign: MAF’s report on New Zealand pesticide use appears just as we launch our programme to achieve an organic New Zealand. This report, the first on pesticide use since 1989, is very timely, for it provides a snap shot of conventional agriculture as it is now, and thus the basis for developing targets along the way towards 2020. It identifies some of the problem areas in chemical agriculture that require urgent research to develop sustainable organic systems. Although pesticide use is only one of the differences between conventional agriculture and organics, it is often the fear of going without chemicals that prevents farmers making the change.
The total quantity of pesticides used in New Zealand’s agricultural (including horticulture) and forestry sectors has remained relatively static over the last 15 years, between 3000-4000 tonnes of active ingredient (a.i.) per year. Usage peaked in 1994 with 3700 tonnes, and fell in 1998 to 3300. According to the MAF report’s authors,1 the latest figures include pesticide use in houses, home gardens, the conservation estate, road and rail berms, “wasteland”, and industrial disinfestation. They exclude ectoparasiticides (pour-ons to control ticks, etc.), vertebrate poisons, timber treatment chemicals and fumigants. They also exclude surfactants and adjuvants.
For a number of reasons, caution is advised in interpreting these figures, particularly in identifying a downward trend in use. Firstly, New Zealand has no mandatory reporting system for pesticide use, so figures must be gleaned from various sources. There is inconsistency in the way these are reported and a lack of co-operation from some companies, particularly in the forestry sector. The margin of error is therefore 10-20 per cent.
Secondly, they exclude the use of mineral oils, estimated to be about 617 tonnes in 1998 but unknown for other years. Mineral oils are used as insecticides and as adjuvants.
Thirdly, several older type pesticides have been replaced by chemicals applied in much lower quantities. For example, the herbicide metsulfuron (Escort) is applied at rates five per cent of those previously used for 2,4,5-T; and synthetic pyrethroids are applied at rates typically two–five per cent of the organophosphate insecticides they replaced. Therefore, although the total amount of pesticide active ingredient used may have decreased, actual area on which pesticides are used, the frequency with which they are used (and hence reliance on pesticides), and their biological effect may not have decreased. They may even have increased. For this reason the change in the total quantity of pesticide used is not, by itself, a good measure of reduction in reliance on, or risks from, pesticides.2
Most pesticides used in New Zealand are herbicides – 68 per cent of the total. Fungicides constitute 24 per cent and insecticides eight per cent (excluding mineral oil). The report notes that over the last ten years insecticide use has decreased, largely because of efforts in researching and implementing IPM. Imagine what will be achieved when similar efforts and resources are expended on organics research.
Herbicides
Glyphosate appears to be the highest use pesticide, followed by the phenoxy herbicides (2,4-D, mecoprop, MCPA, MCPB). Triazine herbicide (e.g. atrazine, simazine) use has increased by 90 per cent in the last decade and, as a result, these chemicals have been found to contaminate groundwater in various parts of the country. Forestry is a high user of the triazine herbicides (165 tonnes).
Expect herbicide figures to fall to zero by 2020, for none of these chemicals are permitted in organic growing, which relies on management, mechanical and thermal techniques to control weeds. Current organic standards do not permit use of essential oil derivatives such as the pine oil extract, Interceptor, or fatty acid-based herbicides like Greenscape. That means a 100 per cent reduction in herbicide use, a 68 per cent reduction in overall pesticide use.
Fungicides
Of the 784 tonnes of fungicides used, nearly half are dithiocarbamates such as mancozeb, maneb, metiram and thiram. These chemicals are metabolised to a substance called ETU, which is considered to be carcinogenic, so removing these from our growing systems is of prime importance.
The second largest group of fungicides contains undesirables such as captan, also regarded as carcinogenic.
The third largest group are termed inorganics, comprising copper compounds, sulphur and phosphorous acid. The first two are permitted in organic production and, although they are not without problems, usage can be expected to increase at least in the medium term. Hence a totally organic country does not mean zero fungicide use, and may even mean an increase in the quantity of fungicide active ingredients used.
Insecticides
Of the 267.5 tonnes of insecticides used, more than half are the toxic organophosphates (150 tonnes). Botanical and biological insecticides such as Bt, neem, pyrethrum, potassium soap, Serratia entomophilia, spinosad and abamectin accounted for 7.7 tonnes. Expect the quantity of this class of pesticides to increase as we approach 2020, for some of these are permitted in organic production. Organophosphates (OPs) and all other insecticides should fall to zero. That means approximately 97 per cent of current insecticide use must cease, or switch to products allowed in organic systems. Note, however, that the figures given exclude mineral oils used as insecticides in both conventional and organic systems. That figure will increase as organic production increases, unless mineral oils are replaced by the more environmentally sustainable vegetable oils.
Plant growth regulators
A total of 101.8 tonnes of these are used in agriculture, and none of them allowed under organic certification. Expect a 100 per cent reduction here.
Pesticide use by crop
The report also analysed pesticide use for a few crops, and this information provides valuable pointers to areas needing concentrated research and to areas where conversion would be relatively easy. Much more of this type of analysis is needed. The authors report that “pesticide usage in asparagus, green peas and sweet corn is relatively low, and is concentrated on early season weed control”. This profile should enable relatively easy conversion to organics. In contrast, fresh vegetables such as lettuces, brassicas and potatoes tend to have “intensive spray programmes throughout the season”. From a health perspective, this makes these crops priorities for conversion to organics, and hence for research assistance.
Onions: By far the worst crop. MAF’s report referred to frequent use of selective herbicides, “relatively intense” insecticide use and “even more intense” fungicide use. Herbicides are used at the rate of 6kg a.i./ha, fungicides at 25kg a.i./ha. Onion white rot (Sclerotium cepivorum) has become established in the Pukekohe district, and “the production of onions in this district is now widely regarded as unsustainable because of the disease and insect problems combined with degradation of the soil resource, runoff and leaching”. Bob Crowder produced excellent organic onions at the Biological Husbandry Unit at Lincoln.
Potatoes: These are subjected to intensive protectant fungicide use – about 10 applications of mancozeb, with total fungicide loading of 20kg a.i./ha. The report failed to mention the post harvest treatment with propham to inhibit sprouting; propham is frequently found as residues in cooked potatoes.
Apples: The introduction of the integrated fruit production programme in the apple sector has resulted in large reductions in OPs, but overall insecticide use remains relatively high with little reduction in fungicide use. Yet excellent results have been achieved with organic apple production, particularly in the Hawkes Bay region.
Dairy, sheep and beef: Pesticide use in pastoral farming is static or declining, according to the report. The main use is herbicides for broadleaf weeds and brush weeds. About 20 per cent of dairy land was treated with phenoxy herbicide. Phenoxies formed the bulk of herbicides used on sheep and beef farms too, followed by glyphosate in both instances. Weed management should not inhibit conversion of these systems to organics although farmers doing so may need a great deal of advice and assistance.
Forestry: High users of triazine herbicides in initial preplant and establishment stages. Little other pesticide is used apart from aerial applications of cupric oxide and mineral oil for Dothistroma needle blight.
The report concludes that weeds are the main priority in New Zealand, “often with no realistic alternative to herbicides”, and fungal infections “continue to provide many challenges for sustainable plant protection”. It also notes a rapid increase in organic production and that all forms of agricultural production now include organics. A major priority, therefore, for an organic New Zealand is to provide farmers with information about the organic approach to, and successful techniques for, weed management. Developing improved weed management techniques is also important.
Although the bulk of pesticide use is for weed management, with farmers frequently seeing weeds as the sticking point in conversion to organics, fungal disease is, in fact, a bigger problem. Chemical fungicide use is not decreasing. New Zealand’s damp, maritime climate means that fungal diseases will always be a problem. This area presents the biggest challenge to organics, not least because the fungicides currently allowed in organics are not wholly benign. It needs a very significant increase in research, in finding alternative products and management techniques, breeding disease resistant cultivars by traditional (non-GE) techniques, and the development of crops more suited to our climate.
In terms of pesticide use reduction, it may be preferable to develop a target for reduction of those pesticides not allowed in organics, rather than an overall reduction of all pesticides, as the latter would disguise the trend towards organics. Currently, total pesticide use is 3300 tonnes. But of this, approximately 150 tonnes of fungicides and seven tonnes of insecticides are permitted in organic systems. Therefore, the target for reduction is 3143 tonnes of active ingredient. Our timeline provides for a 75 per cent reduction in national use of pesticides by the year 2007. This is a decrease of 2357.25 tonnes. That’s the first target.
References.
1. Holland, P., Rahman, A. 1999. Review of Trends in Agricultural Pesticide Use in New Zealand, MAF Policy Technical Paper 99/11.
2. More information on this problem can be found in Watts, M, Mcfarlane, R. 1997. Reducing Reliance: A Review of Pesticide Reduction Initiatives, Pesticide Action Network Asia and the Pacific, Penang. Available from the author.
MAF’S TOXIC SPRAYING IN AUCKLAND
Throughout the latter half of 1999, MAF conducted an intermittent spray campaign against the painted apple moth. This insect invader was found first in Glendene in West Auckland, then to the east in Mt Wellington, and then again back in Glendene. There are remarkable differences between the way MAF conducted this campaign and the way they conducted a previous insect eradication programme, that of the tussock moth. These differences raise alarm bells about the behaviour of this government department.
The two biggest problems are MAF’s failure to involve the public, including public interest groups such as Soil & Health, in the process, and their reversion to the use of toxic chemicals in urban areas.
Firstly the failure to involve the public. MAF, under the guidance of former minister John Falloon, went to considerable lengths to communicate with the people who lived in the tussock moth infested area, and with NGO groups who work on behalf of the public’s interests. MAF held public meetings and organised working meetings for NGO groups. I was included in the science advisory group because of my work on behalf of the public on pesticide issues. This enabled us to head off any suggestions of resorting unnecessarily to synthetic chemicals, a stratagem that was vindicated by the subsequent complete eradication of the pest without chemicals. Such involvement of public interest groups in the process should have acted as a model for other government agents and particularly for MAF itself. But, apparently, MAF has already forgotten the lessons learned.
The second problem probably explains the first. Despite the outstanding success of the organics spray, Btk, in the tussock moth control programme, MAF reverted to the use of toxic chemicals. Btk achieved complete eradication of the tussock moth, something very difficult to achieve even with the most toxic chemicals. Yet MAF chose the chemicals next time. No consultation, just an authoritarian decision. Not only did they choose to use two toxic chemicals, but one of them is under a gathering cloud in the USA.
The dangers of chlorpyrifos
The chemical of concern is the organophosphate insecticide, chlorpyrifos, marketed as Dursban or Lorsban. In a recent review of chlorpyrifos, the US Environmental Protection Agency (EPA) found that exposure to chlorpyrifos on the skin, in food, or by inhaling could be harmful to human health. It can cause blurred vision, muscle weakness, headaches and problems with memory, depression and irritability.1
The greatest problem with exposure to chlorpyrifos occurs with pregnant women and small children. Chlorpyrifos is a neurotoxicant with evidence of developmental neurotoxicity in both animals and humans; there are also reports of neurophysiological effects in humans according to the US EPA. Animal tests show that even low dose exposure to this chemical can seriously affect the foetus, interfering with brain development and causing long-term neurochemical and behavioural deficits in offspring. Newborn children are at greater risk than adults because of a lesser ability to detoxify this chemical. Chlorpyrifos causes significant inhibition of plasma and red blood cells in animals.1, 2, 3, 4
Multiple chemical sensitivity researchers point to chlorpyrifos as one of the major causes of the onset of this syndrome, at least in the USA. Its involvement stems from the damage it does to the neurological system.4
Chlorpyrifos causes environmental problems too: unlike Btk it is a broad-spectrum insecticide, and kills all insects, not just moths and butterflies. Most insects are not pests but valuable members of the ecosystem. It is reported to be very highly toxic to fish and estuarine and marine organisms, and is also toxic to birds. Cats are very sensitive to chlorpyrifos, in particular being susceptible to delayed neuropathy. Earthworms too are susceptible to chlorpyrifos poisoning, especially the species Lumbricus rubellus.5
Government action?
The US EPA review of chlorpyrifos is part of its overhaul of pesticide registration because of a new law that requires extra protection for children. This is in recognition of the vulnerability of children’s developing nervous, immune and endocrine systems to pesticides. The New Zealand government has not yet recognised children’s greater vulnerability to pesticides and so probably will do nothing about the American findings. When last the US EPA found two organophosphates to be of concern, namely methyl parathion and azinphos methyl, they lowered the level allowable in food by a factor of ten. The NZ government’s response was to do nothing, on the grounds that there was no scientific evidence that they needed to. In other words, the benefit of uncertainty was given to the chemical not to children. No doubt this will be MAF’s response again, since it is MAF that registers the pesticides it uses in its own spray programmes. If only MAF would use the same rationale on its other activities, for there was no scientific evidence that it needed to use a toxic chemical to eradicate painted apple moth.
As we more towards our target of New Zealand being organic by 2020, a target we expect to be supported by the new government, it is quite evident that MAF needs to readdress its pest control and public participation methods. It has already proven it can do it the organic way. Now all it needs is confidence in its own success with organics, together with public input to assist it achieve its goals.
References:
1. US EPA. 1999. Chlorpyrifos: HED Preliminary Risk Assessment for Reregistration Eligibility Decision (RED) Document, October 18, 1999.
2. US EPA. 1998. Hazard Assessment of the Organophosphates. Report of the Hazard Identification Assessment Review Committee, July 7, 1998.
3. Landrigan, P.J., Claudio, L., Markowitz, S.B., Berkowitz, G.S., Brenner, B.L., Romero, H., Wetmur. J.G., Matte, T.D., Gore, A.C., Godbold, J.H., Wolff, M. 1999. Pesticides and inner-city children: exposures, risks, and prevention, Environmental Health Perspectives 107(S3): 431-437.
4. Ashford, N., Miller, C. 1998. Chemical Exposures: Low Levels and High Stakes, second Edition. Van Nostrand Reinhold, New York.
5. Cox, C. 1995. Chlorpyrifos, part 3: Ecological effects. Journal of Pesticide Reform 15(2):13-19.
