The development of automated spray drop analyzers has moved from early types using automation only to scan photographic negatives of drops caught on a solid or liquid substrate to in situ type devices capable of sampling a spray cloud in the air. The ruby laser has added the latest development, providing for broad drop size spectrum analysis with both imaging and light scatter techniques. Data taken with a ruby laser instrument with selected pesticide spray atomizers indicate the effects on drop size of (1) increasing atomizer throughput, which increases drop size, and (2) varying angle of spray discharge to airstream for fan and hollow cone type sprays. Increasing the spray angle decreases the drop size. Data on a rotary atomizer at one peripheral velocity and one throughput are also shown.
Closed transfer of pesticide chemicals from the shipping container to a closed mixing tank and thence to the application machine is but one part of a long range program to protect and improve on the health and safety of workers who handle and apply pesticides. Admittedly the task of maximizing safety in the use of pesticides is far from accomplished, but no one can deny the necessity for moving as quickly and expeditiously as possible toward improvement in this troubled area of farm worker safety. The use of closed systems has reduced the number of illnesses of mixer/loader personnel. Environmental contamination is also discussed.
Biopesticide materials are increasingly used in forestry, agriculture and vector control. Their low mammalian toxicity and low environmental hazard potential has encouraged researchers and applicators to evaluate their control potential for a variety of insect pests. However, the resulting formulations of these materials, primarily Bacillius thuringiensis (Bt) and baculoviruses, have not been easy to use under field conditions. Additionally, their physical properties and equipment for applying them did not meet the desired drop size of 80 to 100 micrometers vmd (or Dv.5)that biologists thought were most desirable. Formulation and drop size studies have been initiated to determine the most suitable atomizers, rotary and hydraulic, to use with the various formulations being developed. Physical properties of these formulations indicate the usual reduction in surface tension to about 50% that of water, which tends to reduce the drop size produced compared with that of water. Density does not appear to be a factor of concern, but viscosity, particularly of the virus formulations, may be over 100 mPa∙s and may cause flow problems in spray equipment or produce a large drop size resulting in poor distribution and reduced control. Several formulations were tested along with various atomizers and data on these are shown.
Solid waste from the processing of tomatoes (Lycopersicum esculentum Mill.) consisting primarily of fruit peels and seeds was incorporated into Yolo sandy loam soil, wetted, and incubated at 10, 20, or 30°C for 32 weeks. At 2‐week intervals the soil was analyzed for NO3‐N, PO4‐P, SO4‐S, Cl, total N, organic C, and exchangeable Ca, Mg, K, and Na. Soil pH and electrical conductivity were measured at the beginning of the study and after 32 weeks. With each increment of dried tomato waste applied at rates of 2.5, 5.0, and 10.0% of air‐dry soil, the total organic C and N content of the soil increased. The amount of NO3‐N released from 2.5% rate of waste at 20°C soil temperature was similar to that released from 60 ppm N applied as (NH4)2SO4. Nitrogen released from waste applied at rates of 5.0 and 10.0% air‐dry soil exceeded the level of N usually applied for crop production at about 76 kg N/ha. Significant interactions occurred on NO3‐N release among waste application rates, soil temperatures, and times. At 10°C, there was an increase in NO3‐N released with each increase in waste application. At 20°C, a NO3‐N increase occurred at 2.5 and 5.0% waste application rates, but the increase was less at 10.0 than at 5.0%. At 30°C, a marked reduction of NO3‐N release occurred between 16 and 32 weeks of incubation at all rates of waste application, but was more acute at 10.0% than at lower rates. A similar response, but of lesser magnitude, occurred with release of PO4‐P. Variability in release of NO3‐N and PO4‐P was attributable to the composition of tomato waste and to microbiological activity. Release of SO4‐S was a function of waste loading rate and time. Essentially, all Cl was released within the first week of incubation. An appreciable increase of K, slight increase of Ca, minimal increase of Na, and no change of Mg was found in the soil after 32 weeks of incubation. Although tomato waste is acidic, soil pH decreased only at the highest loading rate after 32 weeks of incubation.
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