Validation of an analytical method for 1,2,4-triazole in soil using liquid chromatography coupled to electrospray tandem mass spectrometry and monitoring of propiconazole degradation in a batch study.

1,2,4-triazole is one of the most important metabolites resulting from the degradation of a large class of pesticides, the triazole fungicides. These fungicides are widely used on fruits, vegetables and cereals. Two different analytical methods which are quick, cheap and easy to implement were developed and validated to monitor propiconazole and 1,2,4-triazole in soil using LC-MS/MS. The limits of quantification reached were 4.0 µg kg-1 for propiconazole and 1.1 µg kg-1 for 1,2,4-triazole. The recovery range was from 93 to 99% with a relative standard deviation <11.2% and from 83 to 97% with a RSD <7.8% for propiconazole and 1,2,4-triazole respectively. These methods: were used to monitor the degradation of propiconazole and the formation of 1,2,4-triazole in soil in a batch study lasting 28 days.

Comparison of efficacy of five types of long-lasting insecticidal nets against Anopheles fluviatilis, the primary malaria vector in east-central India.

Five types of long-lasting insecticidal nets (LNs), namely, Olyset, Netprotect, PermaNet, DuraNet, and Interceptor, were tested after 20 washes for efficacy in terms of mortality, deterrence effect, blood-feeding inhibition, and induced exophily of the malaria vector Anopheles fluviatilis in experimental huts in Malkangiri district of Odisha State, India. Efficacy of the three synthetic pyrethroids (SPs) used in the LNs was also analyzed. Use of LNs reduced the entry of An. fluviatilis into the huts by 73.3-83.2%, and the five LNs were comparable in terms of deterrence. The exit rate of An. fluviatilis from the huts with untreated net was 56.3%, and relative to this, Olyset followed by DuraNet induced significantly a higher exophily. In contrast, the exit rate was significantly lower with Interceptor. Among the three SPs, permethrin induced significantly greater exophily relative to the untreated control, and as a result of this, permethrin-treated Olyset produced a lower mortality. Blood-feeding rate of An. fluviatilis was significantly lower with all the five LNs than the control. Similarly, all the three SPs significantly inhibited blood feeding compared with the control. Interceptor and DuraNet, both alphacypermethrin-treated LNs, caused relatively a higher mortality of An. fluviatilis than the other LNs. The five brands of LNs and three SPs tested in the current study were equally effective in terms of deterrence and blood-feeding inhibition; only exiting and killing effect differed among them. Permethrin-treated LNs induced greater exophily, while, overall, alphacypermethrin-treated LNs killed more An. fluviatilis that entered the huts. Advantage of deterrence, excito-repellent, and killing effects of LNs and appropriate selection of SP for net treatment are discussed in this paper.

Vegephy: impact of vegetable oils used as extemporaneous additives on pesticide residues and their crop protection potential.

Within the framework of the VEGEPHY project set up to assess the effect of refined oils used as extemporaneous additives, both alone and in combination with oligosaccharides (guar, xanthan and carboxymethyl cellulose), on the quality of plant protection treatments for wheat, a study was conducted on the effect of combinations of additives on the level of pesticide residues in wheat plants and grain and their impact on treatment efficiency. The use of some of these additives gave efficiency results that were comparable with those obtained with additives that are currently used but are not bio-based. The use of refined oils as extemporaneous additives, both alone and combined with oligosaccharides, led to better penetration by the pesticide as well as longer persistence of its activity. The experiments were conducted with fungicides, herbicides, plant growth regulators and various types of formulation (EC, SC and WG). The results obtained were conclusive, but they did depend on the physico-chemical properties of the active substance. The risk of exceeding the maximum residue levels (MRLs) of pesticides was also evaluated. Even where the MRLs had not been not exceeded, the experiments showed that in some cases the treatment with these additives could lead to pesticide residues up to two times higher than those measured for the treatment without additives. It would be necessary, therefore, to reduce the treatment dose associated with the additive and/or have a long enough pre-harvest interval to avoid exceeding the MRLs. The use of green additives could be a useful and easy way to attain the European Union (EU) goal of reducing pesticide use by improving the retention of active substances on the plant and reducing the number of treatments.

Biofilters to treat the pesticides wastes from spraying applications: results after 4 years of study.

Biofilters were developed in order to eliminate or reduce the quantity of pesticides from rinsing and cleaning waters of sprayers. Biofilters consist in 1, 2 or 3 plastic containers of 1 m3 placed in a vertical pile and containing a substrate elaborated from a homogenised mixture of local soil, chopped straw and compost able to absorb and degrade the pesticides. Biofilters are installed near the area for cleaning and rinsing the sprayer and the waste waters are pumped into the system. Since 2002, a pilot study is carried out in Belgium in order to evaluate the efficacy of these systems. Twenty pilot systems were installed since 2002 until 2004 in several farms, agricultural technical centres or schools and in a municipal maintenance service. The efficacy of the biofilters was studied for several chemical classes of herbicides (sulfonylurea, aryloxyalcanoic acids, chloroacetanilides), insecticides (pyrethroids, carbamates) and fungicides (dicarboximides, phenylamides, triazoles and strobilurines). The balance of the inputs and the outputs of the pesticides was determined by monitoring the elutes. The degradation kinetic of pesticides into the substrate was evaluated by analysing the pesticides into the substrate. The microbiological activity of the substrate was also evaluated by measuring respiration and some indirect parameters like dry matter content, Kjeldahl nitrogen content, organic carbon content and biological oxygen demand (BOD). Results obtained until now after four years of experiments have showed an overall good efficacy (retention) of pesticides by the biofilter and a high degradation rate for the majority of pesticides. Biofilters permit to reduce highly the quantity of pesticides from rinsing and cleaning waters of sprayers and contribute significantly to the reduction of the contamination of surface water. Biofilters are now registered by the Ministry of Agriculture and Environment of the Walloon Region in Belgium and are recommended to pesticides users.

Influence of the spraying system on fungicides distribution on wheat plants.

Three trials were carried out during springs 2003 and 2004 to compare the distribution of fungicides on the different leaf layers of wheat plants. Mixtures of 1 L/ha of Amistar (SC, 250 g/L of azoxystrobin) and 1 L/ha of Opus (SC, 125 g/L of epoxiconazol) were applied using two experimental sprayers carried by hand and three farmer's sprayers (including a Hardi TwinFlow one). Working pressure, speed, boom length, nozzles, volume of mixture per hectare were specific to each material. One to six days after the treatments, leaf samples were collected at each canopy level and the amount of both active ingredients was determined using gas chromatography with electron capture detection (GC-ECD). The distribution pattern of the fungicides on the different leaf layers was not affected by the spraying system. In the same way, neither the used equipments, nor the mixture volume per hectare, nor the air flow of the Hardi TwinFlow sprayer did not significantly influence the distribution of fungicide.

Development of biofilters to treat the pesticides wastes from spraying applications.

Several studies carried out in Europe showed the importance of direct losses to the contamination of surface water by pesticides. These pesticides losses can occur at the farm site when the sprayer equipment is filled with the pesticide formulation (spills, overflowing, leaking) and during the clean-up (rinsing) of the sprayer after the treatment. In Belgium studies are carried out on biofilters to treat in an efficient way effluents containing pesticides. The biofilter substrate is elaborated from a homogenised mixture of local soil, chopped straw and peat or composted material, able to absorb or degrade the active substances. Biofilters consist in systems of 2 or 3 units depending on the spray equipment of the farmer and on the configuration of the farmyard. Each unit is made from a 1 m3 plastic container and the different units are stacked in a vertical pile and connected between them using plastic valves and pipes. Eight pilot systems were installed in March 2002 in seven farms and in one agricultural school, all selected in the loamy region of Belgium specialised in arable crops such as cereals, sugar beets and vegetables. The efficacy (yield) of the systems was determined by measuring the balance of the inputs and outputs of the pesticides. Results were expressed in percent of pesticide retained on the biofilters. The results obtained after two years with 5 tracer pesticides (atrazine, carbofuran, diuron, lenacil and simazine) brought on the biofilter installations are very satisfactory since the percentage of retention is generally higher than 95% of the amount applied. In the beginning of 2004, ten new pilot biofilters were installed in several farms or agricultural technical centres (producing cereals, sugar beets, potatoes, vegetables, fruits or ornamental plants), and in a municipal maintenance service. Some biofilters were installed in duplicate in order to compare the efficacy of different substrates. The efficacy of the biofilters was studied for the 5 classical tracer pesticides but also for other chemical classes of herbicides (sulfonylurea, aryloxyalcanoic acids, chloroacetanilides), insecticides (pyrethroids, carbamates) and fungicides (dicarboximides, phenylamides, triazoles and strobilurines). To monitor these pesticides in elutes and substrates, two analytical methods were developed, optimised and validated : the first one by Gas Chromatography with Mass Spectrometry Detection (GC-MS), and the second one by High Performance Liquid Chromatography with UV Diode Array Detection (HPLC-DAD). The micro-organisms activity in the substrate was also measured in some situations.

Fate of epoxiconazole and kresoxim-methyl in wheat according to time of application.

During the 2000-2001 season a field trial was conducted with the aim of quantifying the distribution and persistence of epoxiconazole and kresoxlm-methyl in the different leaf layers of winter wheat plants. In the case of applications before flag leaf emergence, the redistribution of the two active ingredients in the newly formed leaves following the applications was also measured. Allegro (125 g/L epoxiconazole and 125 g/L kresoxim-methyl, SC) was applied at the manufacturer's recommended rate (1 L/ha) either in a single treatment at stages GS32, GS39 and GS59 or in 2, 3 or 4 split applications. Following spraying, leaf samples were collected over time, from each leaf layer, and the two active ingredients were quantified by gas chromatography with electron capture detection (GC-ECD). Fungicide distribution varies according to time of application. A descending gradient through the leaves was observed in the case of application at GS59. When sprayed at stage GS39, on the other hand, the second leaf intercepted more fungicide than the flag leaf. Kresoxim-methyl was found to degrade faster than epoxiconazole. With split treatments, the last spraying appears to be very significant in terms of final fungicide quantities. Redistribution appears possible, especially in the case of epoxiconazole, though in very small quantities.

The heterogeneity of sprout inhibitor application with chlorpropham.

The CIPC or chlorpropham is used on potatoes as "sprouting inhibitor". These lasts years, some set of belgian potatoes treated by CIPC exceeded the Maximum Residue Limit (MRL), fixed at 5 mg/kg. The heterogeneity of sprout inhibitor application would be one of the causes of over-dosage. In order to estimate the distribution of CIPC between potatoes, according to the formulation used (DP, EC and HN), a research project financed by "le fond budgétaire des matières premieres" has been set up. In order to evaluate the distribution of CIPC into the pile of potatoes, the efficiency of the different formulations as well as the residues caused by their application on tubers, some tests have been placed in the storage hall. These tests consist in taking off some samples at different places into the pile of potatoes during storage and destocking. The content of CIPC is analysed by capillary gas chromatography with detection by mass spectrometry detection (GC-MS) or nitrogen specific detection (GC-NPD). To estimate the efficiency, the sprouting are observed every month and samples of potatoes are taken off on the top of the pile to control the evolution of CIPC content. Considering the results of the tests, the inhibitor treatment with the formulation DP+HN seems to be the more efficient. As for the residues, the formulation DP leads to a higher content of CIPC than HN, that has a very low concentration. After treatment, the quantity really applied on tubers depends on the formulation used. In fact, 50% of CIPC applied by DP formulation are found on tubers but hardly 10%, after gas application.

Study of potatoes' sprout inhibitor treatments with chlorprophame.

Studies carried out in 1999 by the University of Ghent showed that 36% of potatoes' samples contained Chlorprophame (CIPC) residues and that 7.9% of them exceeded the maximal limit of residues (RML), fixed at 5 ppm. The heterogeneity of sprout inhibitor application would be one of the causes of over-dosage. However, this heterogeneity would also cause under-dosages leading to problems when controlling the sprouting in potatoes stored over 6 degrees C. This study aims at determining some technical causes of the heterogeneity of CIPC sprout inhibitor treatments when storing potatoes. The study concerns two treatment techniques: dusting and spraying. To draw up an inventory of mechanical treatments in Belgium, a survey has been conducted among 28 farmers throughout Belgium. 35 samples have been taken at random in the different storage rooms to analyse the content of CIPC residue. In order to do so, a method of analysis: the gas chromatography in capillary phase with detection by mass spectrophotometry, has been developed. Tests have been carried out by changing several parameters such as the material, the product or the place in the storage line, in order to assess the CIPC application techniques. The survey made it possible to analyse qualitatively, from the declarations of farmers, the causes of heterogeneity linked to treatment techniques. An almost systematically over-dosage of the CIPC quantity has been noticed. However, out of the 35 samples analysed, only 2 had residue contents higher than the RML. The comparative analysis of the quantities applied and the residues contained in the samples made it possible to quantify the heterogeneity of the applications depending on the techniques. The tests carried out show in a general way that mechanical dusting, even though having a less constant flowrate than sprayers, leads to less important variation of the residue between samples. In testing conditions, the heterogeneity of the antigerminative treatment decreases when applied by means of a mechanical duster. In practise, these results are distorted by topical applications of CIPC. The combination of this practise with a too high heterogeneity of the treatment are to be avoided in order to have a good preservation and meet the residues standards.

Rinsing and management of pesticides' containers.

In order to reduce the effects on the environment, it is necessary to improve the management of pesticides' containers. Usually, users burn or bury empty containers. These methods, even though decreasing must be avoided or even forbidden. Since 1996, empty containers are systematically collected in Belgium and are specifically removed by the firm Phytofar Recover created by the Belgian Federation of pesticides' manufacturers. Since the beginning, the recovery rate (percentage of containers recovered compared with the containers sold) goes on increasing to exceed 85% in 2001. These action and results are a world first (more than 500 tons of empty containers are collected yearly). Once collected, empty containers are subjected to the European Policy about toxic wastes since they contained dangerous products. Their removal must follow a specific removal process by incineration at very high temperature (> 1200 degrees C) with a specific filtration of the smoke. The treatment cost is high and reaches 2 Euros per kg of container. If the container is rinsed and the residue does not exceed 1000, 10,000 or 30,000 mg per kg of container (depending on the dangerousness of product: very toxic, corrosive or toxic), it will be considered as domestic waste and will therefore follow a much more economical energy production process. The study aims at determining the quantities of residue contained in empty containers and the parameters reducing the rinsing efficiency: the formulation (EC, WP, WG), the container's size, packaging's type (plastic container or paper bag), the rinsing technique. Almost 150 tests and analyses of residue have been carried out. A manual rinsing procedure has been set up in order to meet the standards about residue. Rinsing three times with an average volume of water (20 to 30%) allows to reach the lowest residue level. As bags containing powder (WG or WP) container not be rinsed, it is necessary to empty them completely. It is however difficult to reach the 1000 ppm residue limit.