Absorption and fate of imazapyr in leafy spurge (Euphorbia esula)

Imazapyr absorption, translocation, root release and metabolism were examined in leafy spurge (Euphorbia esula L.). Leafy spurge plants were propagated from root cuttings and [¹⁴C]imazapyr was applied to growth-chambergrown plants in a water + 28% urea ammonium nitrate + nonionic surfactant solution (98.75 + 1 + 0.25 by volume). Plants were harvested two and eight days after herbicide treatment (DAT) and divided into: treated leaf, stem and leaves above treated leaf, stem and leaves below the treated leaf, crown, root, dormant and elongated adventitious shoot buds. Imazapyr absorption increased from 62.5% 2 DAT to 80.0% 8 DAT. Herbicide translocation out of the treated leaf and accumulation in roots and adventitious shoot buds was apparent 2 DAT. By the end of the eight-day translocation period only 14% of applied ¹⁴C remained in the treated leaf, while 17% had translocated into the root system. Elongated and dormant adventitious shoot buds accumulated 3.2- and 1.8-fold more ¹⁴C, respectively, 8 DAT than did root tissue based on Bq g^?1 dry weight. Root release of ¹⁴C was evident 2 DAT, and by 8 DAT 19.4% of the ¹⁴C reaching the root system was released into the rooting medium. There was no metabolism of imazapyr in crown, root or adventitious shoot buds 2 DAT; however, imazapyr metabolism was evident in the treated leaf 2 and 8 DAT. Imazapyr phytotoxicity to leafy spurge appears to result from high imazapyr absorption, translocation to underground meristematic areas (roots and adventitious shoot buds), and a slow rate of metabolism.     

Environmental fate of mineral,vegetable and transesterified vegetable oils

Vegetable oils, synthetic esters (including transesterified oils) and mineral oils are the main classes of oil used in pesticide formulations. Biodegradation is a major route for the removal of oils from soil systems. Most of the oils used in pesticide formulations are degraded substantially in the laboratory tests that are used to assess aquatic biodegradability. The susceptibility of different oils to biodegradation can be explained in terms of the metabolic capacity of common microorganisms. Fewer soil biodegradability tests have been carried out with oils, but the available data suggest that the mode of degradation is not very different from that in aquatic systems. Supplements of inorganic nutrients (in particular nitrogen) are needed to stimulate microbial activity in soils containing the high concentrations of oil that can be encountered in the event of a spill. However, oils are applied at such low rates in pesticide form illations (maximum of 5g oil m^? soil) that nutrient availability is unlikely to affect the rate of biodegradation in the field.     

The effects of diflubenzuron on the growth of insect cuticle

Cuticle consists of chitin microfibrils embedded in a matrix composed largely of hydrated proteins. The effect of diflubenzuron, an inhibitor of chitin synthetase, on the deposition of both these components is reviewed. The polymerisation reaction is but one step in the pathway leading to chitin microfibrils. Possibly interactions to other steps in the pathway serve to enhance the consequences of the inhibition. Such enhancement could help to explain the abrupt changes in the rate of chitin synthesis that can be observed as diflubenzuron is cleared from epidermal cells. Cuticle proteins differ widely in their ability to form a stable layer when chitin is largely absent. In the most stable regions, diflubenzuron has no effect on the amount or nature of the proteins deposited. In contrast, there are many regions where the deposition of solid cuticle is stopped, presumably because the proteins involved cannot form a coherent layer. Intermediate degrees of stability are found. There is an association between the regions of stability and those of high sclerotisation; though sclerotisation often takes place long after deposition. Even when the protein layer is fairly stable it may not be deposited in a regular manner. This statement is illustrated by electron micrographs of cuticle from the hind tibiae of adult locusts. These micrographs also show that diflubenzuron can affect epidermal cells. In normal cells the plaques are in contact with the newly secreted cuticle; they are still present but this contact is not maintained after treatment with diflubenzuron.     

Effect of furosemide on urine specific gravity and osmolality in thoroughbred racehorses

Postrace urine samples from thoroughbred horses were examined to compare osmolality and specific gravity between horses treated with furosemide and those not treated. Samples were assigned to groups in relation to reported medication (furosemide) status, race finish position, and distance of race. Urine osmolality was significantly (P <.05) lower in samples from horses treated with furosemide when compared with untreated horses. Specific gravity determinations are less precise at measuring urine osmolality at lower levels (1.01 g/ml or less). The measurement of osmolality is a superior method for determining the urine solute concentration and facilitating the regulation of furosemide.