Alam Sundaram

Environmental persistence and impact of diflubenzuron in a forest aquatic environment following aerial application

Dimilin® WP-25 (diflubenzuron) was applied at a rate of 70 g active ingredient (AI) in 10, 5, and 2.5 L/ha to three spray blocks in a mixed boreal forest near Kaladar, Ontario, Canada. Water, sediment, and aquatic plants were collected from two ponds and a stream at intervals up to 30 days post-treatment for analysis of diflubenzuron (DFB) residues. The duration of detectable residues was different for each substrate, but in all cases was less than two weeks. Zooplankton and benthic invertebrate populations were monitored for up to 110 days post-spray in two ponds in the high volume rate block and in control ponds. Significant mortality occurred in two groups of caged macroinvertebrates (amphipoda and immature corixidae) 1 to 6 days after the ponds were treated with Dimilin. Three taxa of littoral insects (Caenis, Celithemis andCoenagrion) were significantly reduced in abundance in the treated ponds 21 to 34 d post-treatment, but recovered to pre-treatment levels by the end of the season. Of the six remaining groups studied, only one (immature corixidae), may have been slightly affected by treatment. Zooplankton (cladocera and copepoda) populations were reduced 3 days after treatment and remained suppressed for 2–3 months.

An improved method to study the impact of pesticide sprays on small song birds

Abstract A survey for possible lead poisoning among workers of silver jewellery industry was undertaken. A large section of population has been engaged in different workshop. The environmental concentration of lead in workshop engaged in recovery of silver from dust, smelting‐alloying and assembling‐soldering have been found to be higher than the permissible limit. Out of 105 workers involved in various processes, 23 subjects were identified as suffering from mild to severe lead poisoning on the basis of laboratory and clinical data.

Influence of formulation properties on droplet spectra and soil residues of aminocarb aerial sprays in conifer forests

The influence of formulation properties on spray droplet spectra and soil residues was studied in conifer forests in New Brunswick following aerial application of two oil-based aminocarb formulations of variable viscosities and volatilities. For a given volume rate of application, the formulation of low viscosity and high volatility provided a spectrum of small droplets and a low volume deposit on ground cards. For the same volume rate, the nonvolatile formulation of high viscosity provided a spectrum of larger droplets and consequently a higher volume deposit. Both formulations provided low soil residues, although those obtained with the nonvolatile formulation were much higher and persisted for much longer periods than those obtained with the volatile formulation. However, with both formulations the soil residues decayed to undetectable levels (less than 3 ng/g) within 5 days after spraying, indicating that none of the formulations caused any undue persistence of aminocarb in forest soils.

Physical properties, droplet spectra and deposits of oils used in pesticide sprays

Abstract The influence of liquid properties on spray atomization and deposition characteristics was studied using two oils of different viscosities and volatilities. For a given volume of oil sprayed, insecticide diluent 585 (ID 585), a petroleum distillate of low viscosity and high volatility, provided numerous small droplets on Kromekote® cards. However, volume of oil deposited was low. For the same volume of oil sprayed, Sun‐spray® 6N, a non‐volatile paraffinic oil of high viscosity provided fewer but larger droplets, and consequently, the volume of oil deposited was much higher on the cards. These observations are explained on the basis of viscosities and volatilities of the two oils.

Effect of a Nalco-Trol II on bioavailability of glyphosate in laboratory trials.

Abstract The effect of a polymeric adjuvant “Nalco‐Trol® II” on bioavailability of glyphosate (in Roundup® formulation), was studied using trembling aspen, Populus tremuloids Michx., seedlings. Absorption and translocation of 14C‐labeled glyphosate was determined with and without Nalco‐Trol II, after application at a dosage rate of 0.35 kg of active ingredient (AI) in 25 L of aqueous solution per ha surface area of leaves. At 48 h after treatment, less than 40% of the applied amount was absorbed and translocated into the plants, and more than 60% was washed away from the treated leaves. Toxic effects of glyphosate (nonlabeled) were assessed for a period up to 28 d after treatment using three parameters, viz., changes in plant height and weight (during 28 d) and chlorophyll content of untreated leaves (during 15 d). The glyphosate‐treated plants showed little increase in height, compared to the control plants, but showed significant reduction in weight and in leaf chlorophyll. No significant differences we...

Effect of adjuvants on glyphosate wash‐off from white birch foliage by simulated rainfall

Abstract The effect of six surfactant adjuvants on glyphosate wash‐off from white birch (Betula papyrifera Marsh.) foliage was studied at 2 and 6 h after treatment with end‐use mixtures of Vision® at the rate of 1 kg of active material in 35 L per ha area of leaf surface. The investigation consisted of two parts. In Part I, C‐labeled herbicide was used to determine the maximum amount of wash‐off (Worst Case Scenario) by rinsing treated foliage with water. At 2 h after treatment ca 84% of the applied amount was washed off when no adjuvant was present, and at 6 h the washable amount decreased only to ca 72%. Out of the six adjuvants tested, only Silwet® L‐77, an organosilicone copolymer surfactant, provided the greatest increase in rain protection, since the amount washed off decreased to 51 and 42% at 2 and 6 h rain‐free periods respectively. In Part II of the investigation, non‐radiolabeled herbicide was used, and glyphosate wash‐off was examined at 2 and 6 h after treatment using cumulative rain of 1 a...

Field deposit patterns of a diflubenzuron spray mix, after application to an apple orchard using an air‐blast sprayer; and a laboratory evaluation of physical properties and atomization characteristics

Abstract Diflubenzuron (DFB) was applied to an apple orchard in Sodus, Wayne County, N.Y., USA, at the rate of 280 g active ingredient (AI) (or 1120 g of Dimilin® WP‐25) in 1430 L/ha, using an air‐blast sprayer’. Deposits were collected at ground level on target site and along downwind direction in the off‐target region, for assessment of droplet spectra and DFB content, before and after treatment. Physical properties, viz., viscosity at variable shear rates, surface tension, volatility and liquid‐atomization characteristics were also investigated for the spray mix under laboratory conditions. About 39% of the applied amount was deposited at ground level of the treated region. Deposits on the off‐target areas decreased extremely rapidly with downwind distance; recovery was about 3% at 15.24 m but reached a level below the detection limit beyond 60 m from the treated area. Droplet frequency (no./cm2) values showed a corresponding decrease. The DFB content of the spray mix, prior to and after treatment show...

Droplet size spectra and deposits of Bacillus thuringiensis aerial sprays, following application at two volume rates over an oak forest

Abstract Dipel® 8AF, a commercial formulation of Bacillus thuringiensis (B.t.) was sprayed undiluted at 30 BIU in 1.8L/ha over a block B1, and sprayed after dilution with water at 30 BIU in 6.2 L/ha over another block B2 in an oak forest infested with the gypsy moth (Lymantria dispar L.) in southeastern Ontario, Canada. Spray was applied in May 1987 using a Cessna 188 Agtruck aircraft equipped with four Hicronair® AU4000 atomizers. Droplet sizes were measured at mid‐canopy level of oak trees and at ground level using cylindrical Kromekote® cards. Deposit per unit area was assessed on aluminum oak leaves. At the lower volume rate of 1.8 L/ha, spray droplets were smaller and droplets/cm2 were lower on the cylindrical Kromekote cards in B1 than those obtained in B2 which received the higher volume rate of 6.2 L/ha. The average deposit per unit area of the aluminum oak leaves, expressed in nL of the spray volume per cm2 surface area, was also correspondingly lower in B1 than in B2. This was attributed to the ...

Influence of surfactant concentration on foliar retention of pesticides used in forestry

Abstract Aqueous tank mixes of permethrin, fenitrothion, Bacillus thuringiensis (B.t.), diflubenzuron (DFB), and glyphosate containing different amounts of Triton® X‐114, a nonionic surfactant, were prepared. Glyphosate formed clear solutions, permethrin and fenitrothion formed emulsions, DFB and B.t provided suspensions. Emulsion stability of permethrin and fenitrothion increased with increasing surfactant level, while the emulsion drop size decreased. Foliage of white oak, trembling aspen, white spruce and balsam fir were dipped in tank mixes of pesticides (except B.t.) labelled with 14carbon. The amount of pesticide retained on foliage was determined by liquid scintillation counting. Foliage was also dipped in non‐radioactive B.t. tank mixes, and the protein retained was determined colorimetrically. With all tank mixes, a direct relationship was observed between the mass of liquids retained on foliage and liquid viscosity. In contrast, the amount of pesticide retained was unaffected by viscosity, but w...

Spray atomization and deposition patterns of one newtonian and two pseudoplastic formulations after aerial application over a mature conifer forest in Newfoundland

Abstract Spray atomization and deposition patterns of three formulations were investigated in five aerial spray trials in Newfoundland, to understand the inter‐relationships between physical properties, drop size spectra and recovery of the spray volume at ground level. Diflubenzuron (DFB) was sprayed at 30 g active ingredient in 2.0 L/ha. Futura XLV (Fu‐XLV) and Thuricide® 48LV (Thu‐48LV), spray formulations of Bacillus thuringiensis (B.t.), were both applied undiluted at 30 BIU/ha, but in volume rates of 2.1 L/ha and 2.36 L/ha respectively. Each of the three formulations was applied over a 15 ha plot using a Piper Pawnee aircraft fitted with six Micronair® AU5000 atomizers. Spray drops were sampled with Kromekote® cards and deposits were collected on glass plates. Physical properties measured were: viscosity at variable shear rates, volatility and surface tension. The viscosities increased progressively from low (for DFB), moderate (for Thu‐48LV) to high (for Fu‐XLV) values, showing a gradual increase i...