First results of the application of a new Neemazal powder formulation in hydroponics against different pest insects

NeemAzal PC (0.5% Azadirachtin) is a new standardised powder formulation from the seed kernels of the tropical Neem tree (Azadirachta indica A. Juss) with an inert carrier. First experiments with beans--as a model-system for hydroponics--show that active ingredient is taken up by the plants through the roots and is transported efficiently with the plant sap to the leaves. After application of NeemAzal PC solution (0.01-1%) to the roots sucking (Aphis fabae Hom., Aphididae) and free feeding (Heliothis armigera Lep., Noctuidae) pest insects can be controlled efficiently. The effects are concentration and time dependent.

Factors affecting microbial formation of nitrate-nitrogen in soil and their effects on fertilizer nitrogen use efficiency

Mineralization of soil organic matter is governed by predictable factors with nitrate-N as the end product. Crop production interrupts the natural balance, accelerates mineralization of N, and elevates levels of nitrate-N in soil. Six factors determine nitrate-N levels in soils: soil clay content, bulk density, organic matter content, pH, temperature, and rainfall. Maximal rates of N mineralization require an optimal level of air-filled pore space. Optimal air-filled pore space depends on soil clay content, soil organic matter content, soil bulk density, and rainfall. Pore space is partitioned into water- and air-filled space. A maximal rate of nitrate formation occurs at a pH of 6.7 and rather modest mineralization rates occur at pH 5.0 and 8.0. Predictions of the soil nitrate-N concentrations with a relative precision of 1 to 4 microg N g(-1) of soil were obtained with a computerized N fertilizer decision aid. Grain yields obtained using the N fertilizer decision aid were not measurably different from those using adjacent farmer practices, but N fertilizer use was reduced by >10%. Predicting mineralization in this manner allows optimal N applications to be determined for site-specific soil and weather conditions.

Nitrogen fertilizer rate and crop management effects on nitrate leaching from an agricultural field in central Pennsylvania

Eighteen pan lysimeters were installed at a depth of 1.2 m in a Hagerstown silt loam soil in a corn field in central Pennsylvania in 1988. In 1995, wick lysimeters were also installed at 1.2 m depth in the same access pits. Treatments have included N fertilizer rates, use of manure, crop rotation (continuous corn, corn-soybean, alfalfa-corn), and tillage (chisel plow-disk, no-till). The leachate data were used to evaluate a number of nitrate leaching models. Some of the highlights of the 11 years of results include the following: 1) growing corn without organic N inputs at the economic optimum N rate (EON) resulted in NO3--N concentrations of 15 to 20 mg l(-1) in leachate; 2) use of manure or previous alfalfa crop as partial source of N also resulted in 15 to 20 mg l(-1) of NO3--N in leachate below corn at EON; 3) NO3--N concentration in leachate below alfalfa was approximately 4 mg l(-1); 4) NO3--N concentration in leachate below soybeans following corn was influenced by fertilizer N rate applied to corn; 5) the mass of NO3--N leached below corn at the EON rate averaged 90 kg N ha(-1) (approx. 40% of fertilizer N applied at EON); 6) wick lysimeters collected approximately 100% of leachate vs. 40-50% collected by pan lysimeters. Coefficients of variation of the collected leachate volumes for both lysimeter types were similar; 7) tillage did not markedly affect nitrate leaching losses; 8) tested leaching models could accurately predict leachate volumes and could be calibrated to match nitrate leaching losses in calibration years, but only one model (SOILN) accurately predicted nitrate leaching losses in the majority of validation treatment years. Apparent problems with tested models: there was difficulty estimating sizes of organic N pools and their transformation rates, and the models either did not include a macropore flow component or did not handle macropore flow well.

Designing herbicide formulation characteristics to maximize efficacy and minimize rice injury in paddy environments

Mathematical descriptors, coupled with experimental observations, are used to quantify differential uptake of an experimental herbicide in Japonica and Indica rice (Oryza sativa, non-target) and barnyardgrass (Echinochloa crus-galli, target). Partitioning, degradation, plant uptake and metabolism are described using mass-balance conservation equations in the form of kinetic approximations. Estimated environmental concentrations, governed by the pesticide formulation, are described using superimposed analytical solutions for the one-dimensional diffusion equation in spherical coordinates and by a finite difference representation of the two-dimensional diffusion equation in Cartesian coordinates. Formulation attributes from granules include active ingredient release rates, particle sizes, pesticide loading, and granule spacing. The diffusion model for pesticide transport is coupled with the compartment model to follow the fate and transport of a pesticide from its initial application location to various environmental matrices of interest. Formulation effects, partitioning and degradation in the various environmental matrices, differential plant uptake and metabolism, and dose-response information for plants are accounted for. This novel model provides a mechanism for selecting formulation delivery systems that optimize specific attributes (such as weed control or the therapeutic index) for risk-assessment procedures. In this report we describe how this methodology was used to explore the factors affecting herbicide efficacy and to define an optimal release rate for a granule formulation.

Delivery of biological performance via micro-encapsulation formulation chemistry

Lambda-cyhalothrin micro-capsules have been prepared by a novel in situ procedure. Manipulation of the chemistry has led to slow- and fast-release formulations. The latter has a biological performance comparable to commercial lambda-cyhalothrin emulsifiable concentrates, but exhibits a significantly improved toxicological profile over EC, WP and WG formulations. Micro-encapsulation technology satisfies many of the drivers towards the safer use of pesticides.

Formation of tetrahydro-beta-carbolines and beta-carbolines during the reaction of L-tryptophan with D-glucose

The reaction of L-tryptophan (Trp) with D-glucose under conditions that can occur during food processing and preparation was studied by high-performance liquid chromatography with diode array detection (HPLC/DAD). Besides the well-established glucose-tryptophan Amadori product (AP), (1R,3S)-1-(D-gluco-1,2,3,4,5-pentahydroxypentyl)-1,2,3, 4-tetrahydro-beta-carboline-3-carboxylic acid (PHP-THbetaC) was identified as an important product of this reaction. For preparation, PHP-THbetaC was obtained in high yields when Trp and D-glucose were reacted under strongly acidic conditions after heating in methanol. At elevated reaction temperatures (150 degrees C) 1-acetyl-beta-carboline (acetyl-betaC), was detected in significant concentrations. The mixtures were heated under variations of reaction time and temperature, and AP, PHP-THbetaC, and acetyl-betaC were quantified. In the presence of air oxygen or mild, food relevant oxidants, such as L-dehydroascorbic acid, PHP-THbetaC was readily oxidized to a product that was identified as the previously unknown 1-(D-gluco-1,2,3,4,5-pentahydroxypentyl)-beta-carboline (PHP-betaC). Formation of PHP-THbetaC and PHP-betaC in foodstuffs would deserve particular interest because multiple physiological activity of THbetaC and betaC derivatives has been shown previously.

Evaluation of hydromatrix and magnesium sulfate drying agents for supercritical fluid extraction of multiple pesticides in produce

The simultaneous extraction of relatively polar and nonpolar pesticides has been problematic in multiresidue analysis using supercritical fluid extraction (SFE) with carbon dioxide. In fruit and vegetable samples, which typically contain 80-95% water, moisture acts to increase SFE recoveries of many polar pesticides, but a drying agent should be used to control water in SFE. Hydromatrix, a prevalent drying agent, has many desirable characteristics, but it reduces recovery of certain important pesticides, such as methamidophos, acephate, and omethoate. MgSO4 has been shown previously to be applicable for the extraction of methamidophos and six other pesticides, but MgSO4 has practical disadvantages in its use. In this study, properties and SFE results with the individual drying agents and their combination were evaluated. Simultaneous recoveries for polar and nonpolar pesticides were achieved for 71 pesticides fortified in apple using a mixture of 2 + 1 + 2 MgSO4-H2O-Hydromatrix-sample for extraction. The advantages of each drying agent were maintained by their combination. The analysis of real samples, however, showed that more study was needed to improve recoveries of nonpolar pesticides.

ETHYLENE ACTION AND THE RIPENING OF FRUITS

Recent studies employing gas chromatography show that an amount of ethylene large enough to stimulate ripening is always present within a fruit before the respiratory climacteric begins. This fact and data from experiments in which fruits were exposed to a partial vacuum or varying concentrations of O(2), CO(2), and ethylene oxide reinforces the view that ethylene is a ripening hormone. The respiratory climacteric begins soon after the fruit is harvested because the tissue no longer receives from the shoot system a substance which inhibits ripening; this substance may act by lowering the sensitivity of the fruit to ethylene. The threshold for ethylene action is also influenced by the composition of the atmosphere, for O(2) is a substrate in the reaction activated by ethylene and CO(2) inhibits the action of ethylene by competing with the olefin for the receptor site. Experiments indicate that ethylene is derived from acetate or acids of the Krebs cycle and acts by binding to a metal receptor site in the tissue.

Japanese guidelines for mutagenicity testing. Ministry of Agriculture, Forestry and Fisheries; Ministry of Health and Welfare; Ministry of Labor

Several Japanese agencies are required to perform mutagenicity tests according to regulatory guidelines. Although each agency's guidelines address a specific purpose, the experimental principles behind them are similar, and general methodological recommendations have been issued by the Ministry of Agriculture, Forestry, and Fisheries [1985]; Ministry of Health and Welfare [1990]; Ministry of Labor [1991]; and Ministry of Health and Welfare [1992]. Four major guidelines for mutagenicity testing in Japan and some amendments are briefly introduced. In addition, several procedures in Japanese guidelines that differ from those of other countries or organizations are discussed.

Mortality experience of employees with occupational exposure to DBCP

Concern about the carcinogenic potential of 1,2-dibromo-3-chloropropane(DBCP) has arisen recently, focusing on six organ sites: stomach, liver, kidney, lung, testes, and skin. To examine the mortality experience of persons potentially exposed, a cohort of 550 employees involved in production and formulation from 1957 to 1976 was defined. A total of 35 deaths was observed through 1979 (39.2 expected). No statistically significant excess was observed for any cause of death. No cancer deaths were noted for five of the hypothesized sites. For the lung cancer category, five deaths were observed (2.7 expected, P greater than .135), two of which occurred in a subgroup directly exposed for at least 1 yr (0.5 expected, P greater than .077). Aside from arsenicals exposure, potential confounding resulting from smoking or multiple chemical exposures could not be evaluated.