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DOZENS OF REPORTS over the last 35 years have documented the decline in the number of students pursuing science and mathematics degrees. For instance, from 1995 to 2000, the number […]

This article examines the relationships between the quality of a machined component and the non-intrusive measurements that can be made during the manufacturing process. For the purposes of this study, the overall quality of a machined component is defined by the surface finish and any residual stress induced by the machining process. The focus of the work involves turning of difficult-to-machine metals and non-intrusive measurements recorded during machining. These measurements were acoustic emission, cutting forces and cutting insert temperature. An austenitic stainless steel was chosen as a commonly available metal whose high work-hardening rate and ability to strain transform to martensite make it potentially difficult to machine. Tests were carried out under different cutting conditions to promote thermally and mechanically induced residual stress and variations in the surface finish. Analysis of the mean frequency of the acoustic emission signal has made it possible to determine whether thermal or mechanical interactions dominate the machining process. The mean frequency of the machined samples provided evidence of a thermally driven process. This was confirmed by the close relationship between cutting insert temperature and component residual stress. The analysis of low-frequency acoustic emission generated during machining (below 100 kHz) identified poor surface finish derived from vibrations of the cutting insert.

Several concentrations of parathion, carbophenothion, disulfoton, and phorate in EC or T formulations were tested in the laboratory on 4 Texas strains (Pecos, Seagraves, Petersburg, and Olton) of Oligonychus pratensis (Banks) to determine baseline LC50 and resistance levels. Considerable resistance was detected in all strains to 3 of the compounds but phorate remained fairly effective for the 3 strains on which it was tested. The LC50 for parathion in the Pecos strain was 60-fold higher than for the most susceptible (Olton) strain tested. The highest LC50 in ppm for each of the chemicals was: phorate-10, disulfoton-1095, carbophenothion-1946, and parathion-2067.

Biotype D greenbugs, Schizaphis graminum (Rondani), were shown to have developed cross resistance within the organophosphate insecticides. Resistance levels to disulfoton ranged from 10.6- to 37-fold over the susceptible Stillwater, OK, strain which had an LC50 of 0.22 ppm at 48 h. Highest resistance levels (17.1- and 37.0-fold) were found in colonies of greenbugs taken from locations of higher insecticide usages north of the Edmonson area where resistance was first reported. Resistance levels were lower (10.6- and 14.4-fold) in colonies from areas east of Edmonson. The more disulfoton-resistant Hereford strain was found to have the highest parathion resistance (2.98-fold). In leaf-dip screening studies on the resistant Hereford strain, chlorpyrifos, oxydemetonmethyl, and carbofuran were more toxic than parathion with LC50’s of 1.12, 1.98, 2.11, and 2.50 ppm, respectively. FMC 35023 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl [(N-benzyl) (N-methyl) aminosulfenyl] [methyl] carbamate), FMC 31768 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl (methyl) (morpholinosulfenyl)-carbamate), FMC 40963 (FMC 33297 plus 2-methylpropyl 2-propynyl phenylphosphonate), permethrin (FMC 33297), thiofanox, A 47171 (1,1-dimethyl 2,2 bis (p-ethoxyphenyl) ethane), and A 47170 (1-chloro 1-methyl 2,2 bis (p-ethoxyphenyl) ethane) were much less toxic with LC50’s which ranged from 3.88 to >80 ppm.

When reared in the laboratory on grain sorghum, the Banks grass mite (Oligonychus pratensis (Banks)) life cycle length was 7–13 days and the total length of life varied from 14–36 days. Six to 14 eggs were laid per female per day with maximal oviposition on the 6th day of adulthood. Age-specific life tables were constructed for one generation under 2 rearing methods, and more than a 70-fold population increase was predicted to occur under the test conditions.

Schizaphis graminum (Rondani) on wheat can still be effectively controlled using the standard parathion and methyl parathion treatments, however, additional insecticides were screened to determine their effectiveness so that alternate effective treatments would be available if these standard chemicals became unusable. Applications of ULV monocrotophos at 0.06, 0.13 and 0.25 lb active ingredient per acre were comparatively ineffective in 1967 studies, while a higher volume spray of parathion and ULV parathion at 0.5 lb gave significant green bug reductions. Two experiments conducted in 1968 showed higher volume sprays of monocrotophos applied at rates of 0.25 and 0.5 lb AI/acre, and disulfoton LC at rates as low as 0.25 lb to be as effective as 0.5 lb of methyl parathion. Studies in 1969 indicated that low temperatures may limit the effectiveness of the compounds tested as the best material, disulfoton at 0.25 lb AI/acre, only reduced the green bug population by 75%. Counts of parasites and predators indicated that their populations were not substantially lowered by application of any of the compounds tested in 1969.

Foliar applications of disulfoton liquid concentrate at rates up to 2.5 lb active ingredient (AI) per acre resulted in negligible burn. rates up to 4 lb AI/acre resulted in slight burn but did not significantly affect yields. Three foliar applications of 0.75 lb AI/acre resulted in less than 0.3 ppm residue in straw and grain samples at harvest in 1968. Application of up to 3.5 lb AI/acre resulted in less than 0.02 ppm in straw and no more than 1 ppm in grain samples in 1969. Residues in foliage samples taken 14 days after the last of as many as 4 applications were 5 ppm or below, except in one case. Seed treated with 0.5 lb AI/cwt resulted in significant stand reductions, but residues were below 5 ppm 14 days after planting.

Chemical control of Contarinia sorghicola (Coquillett), attacking grain sorghum, Sorghum bicolor (L.) Moench, in Argentina can be effectively accomplished with the same chemicals used in Texas. The average weight of threshed grain per head was increased by most treatments even when one-half the recommended rates were applied only once. Carbophcnothion, diazinon, toxaphene, and carbaryl were among the best compounds tested.

Grain sorghum, Sorghum bicolor (L.) Moench, was first attacked by Contarinia sorghicola (Coquillett) in highly damaging numbers on the High Plains of Texas in 1961. Aerial applications of parathion, toxaphene and a combination of the two applied to sorghum in the mid bloom stage in 1961 resulted in increased yield. Field adult-midge counts, midge emergence from treated heads, and yields indicated the parathion (0.25 lb AI/acre) and toxaphene (1.3 lb AI/acre) combination was superior. Plotting of blooming date against midge damage showed significant damage did not occur to plants blooming prior to mid-August. Neither sorghum variety nor head type influenced the amount of damage. Chemical control tests in small plots conducted in 1963-64 showed DDT, carbophenothion, parathion, diazinon, and ethion applied twice 4 days apart at 0.5 lb AI/acre gave superior control of high midge populations. Methyl parathion also was effective at this rate, but phytotoxic properties limited its use. Endrin at 0.3 lb AI/acre was effective only under low-population conditions.

A large population of mites, primarily Oligonychus pratensis (Banks), was reported attacking grain sorghum, Sorghum bicolor (L.) Moench, in the Hereford, Texas, Area in 1967. A 2-year study in the Hereford area showed that Supracide® (O,O-dimethyl phosphorodithioate S-ester With 4-(mcrcaptomethyl)-2-methoxy-&incrmnt;2-1,3,4-thiadiazolin-5-one) disulfoton (both as granular and ligquid concentrate formulations), and carbophenothion applied at 0.5 lb AI/acre were the most effective treatments. Monocrotophos, diazinion, and ULV Supracide offered some control capabilities at the 0.5 lb AI/acre rate. Applications were made in 1967 and 1968 on sorghum in the early-soft-dough to hard-dough stages of plant growth. It was determined that yields were not significantly in creased by reduction of the mite populations. Observations on parathion-treated fields indicated increased yields after mites were controlled on young sorghum. Higher incidence of plant lodging was observed in heavily infested sorghum fields. Subsequent studies in 1969 near Pecos, Texas, involved 20 acaricides, and Supracide was determined to be signigicantly more effective than the others in controlling the acaricide-tolerant mites which were encountered. Investigations on sorghum conducted in 1970 near Hereford Determined that Supracide remained effective in most cases, but carbophenothion, disulfoton, and parathion were relatively ineffective at 0.5 lb AI/acre. These date indicated that acaricide resistance was increasing in the mite populations. Granular phorate applied at 1 lb AI/acre was found to be effective, and acaricidal activity was increased in sorghum and corn plots that were iriated following application. Yield increases were observed during 1970 in both sorghum and corn plots where effective acaricides were aerially applied.

A new biotype of Schizaphis gramimun (Rondani) caused severe and widespread damage to sorghum, Sorghum bicolor (L.) Moench, in the summer of 1968. Screening tests and refinement of application rate studies were conducted in 1968 and 1969 to determine if compounds used in greeubug control on wheat could be used effectively also against this biotype. The most feasible chemicals, considering both insecticidal and nonphytotoxic properties, were disulfoton, parathion, diazinon, demeton, and ULV malathion. Carbophenothion, although somewhat slower acting, was also usually very effective. Supracide® (S-((2-methoxy-5-oxo-&incrmnt;2-l,3,4-thiacliazolin-4-yl) methyl) O,O-dimethyl phosphorodithioate), while not very effective in the 1968 studies, significantly reduced greeubug populations in the 1969 tests. Most of the insecticides were found to give reductions also in populations of the corn leaf aphid Rhopalosiphum maidis (Fitch). Fall armyworm, Spodoplera frugiperda (J. E. Smith), and flea beetle population differences following insecticidal treatments were not significant. Of the beneficial insects monitored, the primary species present were the convergent lady beetle, Hippodamia convergens Guérin-Méneville, and various parasitic Hymenoptera. In general the more effective the insecticide in controlling the greenbug, the greater its suppressive effect Avas on beneficial insect populations. However, demeton applied at 0.5 lb active ingredient per acre gave satisfactory greenbug control and spared much of the beneficial insect population.