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Assessment of urea impact on some physical and chemical characteristics of insecticides working solutions

The paper deals with the role of urea as an antievaporator in working solutions of microbial and chemical insecticides of different classes of chemical compounds and preparations. Evaporation was determined with express-method based on weight determining of mass loss rate from the wetted surface. Determination of surface tension of liquids was carried out using stalagmometric method.
The amount leaking from a certain volume of liquid in stalahmometr depends on its surface tension (inversely proportional relationship). Distilled water was the standard for comparison.
It was found out that addition of 20 % Сarbamide to working solutions of chemicals of various classes of chemical compounds and preparations reduces drops evaporation significantly.
The difference in the rate of evaporation was noticeable 2 minutes after applying the liquid to a piece of cover glass.
If during this period Korahen and Konfidor solutions evaporated without additives by 24 and 31 % respectively, the mixture of Сarbamide evaporated by 9 % only. The figure was 78 and 64 or 28 % and 29 % respectively in 8 minutes. The water evaporated completely (100 %) within this period.
Similar results were recorded under addition of Сarbamide to bacterial suspensions of Bitoksybatsylin and Lepidotsyd bacterial biopreparations. The water evaporated completely in 8 minutes, while the substance without additives evaporated by 71 % and 63 %, respectively, and under addition of Сarbamide – only by 39 % and 40 % respectively. Other nitrogen fertilizers like ammonium nitrate and 50 % Plav (mixture of Nitrate ammonium and Сarbamide) are known to have good antievaporator characteristics.
However, because they create an acidic environment (pH = 4.0), unlike Сarbamide (pH 6.9) should not use them because most microorganisms developing in a neutral environment and suffer oppression in acidic and more alkaline environment.
Surface tension rate in freshly made solution of chemical and microbiological preparations ranges 41.1-71.2 din/cm2 and is acceptable, since in most cases lants leaves and insects are sufficiently wetted under the solution surface tension of 40-50 din/cm2.
However, unlike the evaporation process, the addition of 0.20 % Сarbamide to aqueous suspensions and emulsions preparations does not affect the surface tension of the solution.
The difference in performance between the surface tension of solutions of various preparations, apparently, can explain quantitative content in its composition of surfactants. High levels of surface tension of microbial preparations suspensions (close to the water level – 72.8 din/cm2), is associated with low surfactant content in their composition (less than 0.05-0.1 % of the total amount of liquid).
Thus, in the medium reaction Сarbamide is compatible with working liquids of chemical and microbial insecticides.
It has a good antievaporator effect since its addition to water emulsions and suspensions preparations results in reduced drops evaporation from the treated surface by more than 1.5 times.
Сarbamide does not affect the surface tension in water emulsions and insecticides suspensions. This figure is determined by the content of surfactants in the composition of chemical and microbiological agents.
The approximate characteristics of working solutions continues 24 hours after the preparation, which gives grounds  to determine the period of their application without the efficiency reducing.
Key words: insecticides, biologics, сarbamide, surface tension, medium pH, evaporation.

 

M. Sekun


V. Berezovska-Brygas


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AGROBIOLOGY №1 2017