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The potential ecotoxicity of fluorescent dyes used in tracing, and their possible effects on human health, were evaluated by reviewing available toxicological information for 12 dyes - fluorescein, Lissamine Flavine FF, Rhodamine WT, Rhodamine B, Sulpho Rhodamine G, Sulpho Rhodamine B, eosin, pyranine, Phorwite BBH Pure, Tinopal 5BM GX, Tinopal CBS-X, and Diphenyl Brilliant Flavine 7GFF - and a dye-intermediate, amino G acid. This evaluation used available toxicological information, test data on analogous substances, and mathematical expressions for biological activity. Based on set criteria for human health and acute ecotoxicity, the evaluation indicated that these tracers have low to moderate levels of concern. The use of these tracers for the study of groundwater flow is appropriate if consideration is given to the overall human health and environmental effects. Their use in the environment requires tracer concentrations not exceeding 1-2 mg 1(-1) persisting for a period in excess of 24 h in the groundwater at the point of groundwater withdrawal or discharge. A simple calculated potential dose was used in a comparison of the estimated acute toxicity of Rhodamine WT in rats to the known acute oral toxic dose in humans for several known acutely toxic chemicals. This comparison showed that none of the fluorescent dyes evaluated would present an acutely toxic threat at or substantially above the recommended 2 mg 1(-1) concentration.

Four fumigants were evaluated during the spring and summer months for disinfesting the space beneath the drying floor in empty 114.5-m3 (3,250-bu) circular metal bins. Fumigant concentrations were monitored at five points beneath the drying floor, and test cages of insects were placed next to the sample lines. The test cages contained adults and eggs of the red flour beetle, Tribolium castaneum (Herbst), and immature stages of the rice weevil, Sitophilus oryzae (L.), and were placed inside cloth bags containing grain dockage. Chloropicrin was effective at the label dosage of 946 ml (32 oz)/bin. A 473-ml (16-oz) dosage of chloropicrin and 3.79-liter (1-gal) and 7.57-liter (2-gal) dosages of a liquid fumigant containing carbon tetrachloride and carbon disulfide did not produce 100% insect mortality. A liquid fumigant containing ethylene dichloride, carbon tetrachloride, and ethylene dibromide did not kill all insects at 3.79 liters, but produced 100% mortality at 7.57 liters per bin. Phosphine was effective at 60 tablets per bin when used beneath a plastic sheet on the drying floor. Without the sheet, phosphine was ineffective at dosages as high as 200 tablets per bin. All fumigants dissipated within 48 h of application. Chloropicrin is the only fumigant currently labeled for empty bin fumigation, and this study showed that it is effective at the label rate. This study also showed that other fumigants, although not currently labeled, are effective if properly used.

Throughout a 9-mo period, chlorpyrifos-methyl was much more effective than malathion in controlling insects on 14.6% moisture red winter wheat stored in plywood bins. However, chlorpyrifos-methyl persisted longer on the wheat than malathion did.

During the prebloom and bloom stages, no movement of labeled photosynthates occurred from a shoot of Vitis vinifera L. fed with (14)CO(2), to an adjacent shoot on the same spur. Movement of labeled assimilates into the unfed shoot was induced when this shoot was sprayed with 2.89 x 10(-3)m gibberellic acid during the prebloom stage. During the bloom stage darkening or defoliation of the unfed shoot resulted in the import of labeled photosynthates from the adjacent fed shoot. Similarly, movement of (14)C into an untreated shoot was induced by removing the terminal 7.5 centimeters and deblossoming the fed shoot. During the berry set stage, translocation of labeled photosynthates from a newly exporting leaf was upwards to the shoot tip, but the direction of movement was reversed by removal of the shoot tip or by darkening or removal of the leaves below the fed leaf. Translocation of photosynthates was predominantly basipetal from a fed leaf near the base of the shoot during the berry set stage, but upward movement was induced by darkening or defoliation of the upper part of the shoot.

Corn storcd in 16 circular metal bins 114.53 m3 (3250 bu) was observed for a period of 15 mo. Four of the lots of corn were sprayed with malathion on the surface, 4 were surface sprayed and a spray applied to the outside wall of the bin, and 4 sprayed only on the outside wall of the bin. The remaining 4 bins served as controls. Samples were drawn to assess the numbers and specics of live insect at monthly intervals. The surface spray application reduced the insect populations whether it was used alone or in combination with the wall spray. The wall spray alone did little to reduce populations.