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Sridhar Polavarapu

A common practice in highbush blueberry (Vaccinium corymbosum L.) culture is to use combinations of insecticides and fungicides to reduce the number and cost of pesticide applications. In response to apparent phytotoxicity observed in commercial fields that were treated with combinations of diazinon and captan formulations, phytotoxicity of two formulations of diazinon (Diazinon AG600 and Diazinon 50W) and captan (Captan 80WP and Captec 4L) was investigated on highbush blueberries during 1997 and 1998. Phytotoxicity injury similar to injury observed in commercial fields was reproduced in treatments with diazinon and captan mixtures in all experiments. The Diazinon AG600 and Captec 4L mixture was the most severe and caused significantly more phytotoxic-ity to fruit and leaves than individual treatments of Diazinon AG600, Captec 4L or untreated control. Separation of diazinon and captan applications by 8 h significantly reduced phytotoxicity compared to mixture treatments. Injured fruit and leaves recovered over time and most treatments showed only a mild injury at the time of harvest. Phytotoxicity on fruit and leaves caused by Diazinon AG600 and Captec 4L mixture was significantly affected by application date with the earliest application causing the greatest injury. These data indicate that diazinon and captan mixtures cause phytotoxicity on highbush blueberries and therefore the two should not be applied in combination.

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Melissa Bonham, Gerald M. Ghidiu, Erin Hitchner, and Elwood L. Rossell

Jersey. Growers currently use multiple foliar sprays of diazinon, esfenvalerate, or cyfluthrin for control of carrot weevil; no other insecticides are labeled for use on carrot in New Jersey. Control of the carrot weevil is difficult because the female

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Salvatore S. Mangiafico, Julie Newman, Donald J. Merhaut, Jay Gan, Ben Faber, and Laosheng Wu

detention or recycling basins ( Mangiafico et al., 2008 ). Commonly detected pesticides included bifenthrin, fenopropathrin, permethrin, diazinon, chlorpyrifos, and DDT and its metabolites; however, the frequency of detection of these pesticides varied by

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John M. Brown, Alan A. Schreiber, and Charles O. Knowles

Control failures of many insecticides used against the western flower thrips (WFT), Frankiniella occidentalis (Pergande), have been reported from several locations by greenhouse operators. To document resistance, thrips were bioassayed by placing them in vials coated with doses of diazinon, methomyl, bendiocarb, dimethoate, azinphosmethyl and cypermethrin at (100, 50, 10, 5, 1, 0.5 and 0.1 g/vial). Adult female WFT were collected from a colony exhibiting control failures using organophosphate, carbamate and pyrethroid insecticides. A colony showing no resistance was used as a control. The LC50's of the resistant and susceptible strains were diazinon 49.3 and 4.6 g/vial, cypermethrin no mortality and 3.7 g/vial, and azinphosmethyl 20.2 and 2.l g/vial respectively. Results show resistance is present as well as cross resistance to diazinon and cypermethrin because the resistant population was never exposed to these compounds.

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Lih-Yuh Yueh and David L. Hensley

The influence of 12 pesticides on C2H4 reduction and modulation of soybean (Glycine max L. Merr.) and lima bean (Phaseolus lunatus L.) was evaluated. All except diazinon were innocuous at 3× the label rate. Diazinon decreased C2H4 reduction of soybean 2 days after application, but not after 7 days or at normal label rates. Nitrogen fixation of excised nodules imbibed with diazinon indicated that it may have directly affected nitrogenase function. Soybean nodule numbers were decreased by application of 3× rates of methomyl and trifluralin, but lima bean nodule numbers were decreased only by trifluralin. Trifluralin also depressed soybean but not lima bean modulation at label rates. Methomyl did not affect soybean modulation at label rate. Both chemicals were non-toxic to Rhizobium sp. in a disc inhibition study.

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Lih-Yuh Yueh and David L. Hensley

The influence of 12 pesticides on acetylene reduction (N2 fixation) and modulation of soybean (Glycine max L. Merrill cv. Williams 82) and lima bean (Phaseolus lunatus L. cv. Geneva) was evaluated. All pesticides except diazinon were found to be harmless to nitrogen fixation at 3× the manufacturer's recommended rate, Diazinon significantly decreased C2H2 reduction of soybean 2 days after application, but not after 7 days or at normal label rates, Acetylene reduction of excised nodules imbibed with diazinon indicated that the chemical may have affected nitrogenase function directly. Soybean nodule counts were significantly decreased by application of 3× rates of methomyl and trifluralin, whereas lima bean nodule counts were decreased only by trifluralin. Tritluralin also depressed soybean modulation at label rates, but had no effect on lima bean modulation. Methomyl was innocuous to soybean modulation at the recommended label rate. Both chemicals were nontoxic to Bradyrhizobium/Rhizobium sp. based on a disc inhibition study. Chemical names used: O,O -diethyl O -(2isopropyl-4-methyl-6-pyrimidinyl phosphorothiote (diazinon); S-Methul- N -((methylcarbamoyl)oxy)-thioacetimidate (methomyl); a,a,a -Trifluoro-2-6dinitro-N-N -dipropyl-p-toluidine (triflnralin).

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Herbert D. Stiles and Paul J. Semtner

Larvae of Contarinia agrimoniae Felt, a gall midge, were discovered during 1986 in blossoms of blackberry cultivars and wild-growing plants that had a history of poor fruit set and `nubbin' formation (Stiles, Semtner, and Reed, 1996). Other species damage blackberries in Europe, but the only North American recognition of Rubus flower bud infestation was with Dasineura rubiflorae Felt during 1886 (Gagne, 1989). During 1995 we found larvae of a Dasineura spp. in damaged buds at two, widely separated, commercial, North Carolina, blackberry sites. It is not known if the latter insects are different from the species that was collected during 1886. Midge larvae probably overwinter in soil under affected plants so we sprayed diazinon on the soil surface before bloom to kill larvae or interfere with pupation and reduce crop injuries. Infested `Shawnee' and `Cheyenne' buds were ≈100% more numerous among controls than diazinon-treated plots. Numbers of larvae varied among infested buds; 83 were observed in one bud from a nontreated `Cheyenne' plot.

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Kristen E. Tollerup and Mark Shelton

Three different treatments were evaluated for preventing the common citrus pest, Argentine ant Iridomymex humilis (Mayr), from foraging in skirt pruned citrus trees. The treatments were: 1) 1% (AI) chlorpyrifos 4 EC applied to the basal 15 cm portion of the trunk, 2) 32 g (AI) diazinon 14G broadcast in a 60 cm radius around the trunk, and 3) a trunk barrier of petroleum wax applied in a 10 cm wide strip around the trunk. The treatments were evaluated in two-week increments from August 1, 1991, to October 20, 1991, by counting the number of ants to cross an arbitrary line 10 cm above the soil surface on the trunk of each tree. Each of the three treatments resulted in a highly significant reduction in the number of ants entering trees compared to untreated control trees. There were no significant differences among the three treatments.

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William G. Hudson, Melvin P. Garber, Ronald D. Oetting, Russell F. Mizell, Ann R. Chase, and Kane Bondari

A national survey of the greenhouse and nursery industry provided data on insecticide/miticide use in 1993. Respondents reported using 46 different compounds, and the industry used an estimated 2.8 million pounds of active ingredients to control insect and mite pests. The most frequently used material was acephate: 52% of the respondents reporting use in 1993. The most heavily used material was a miticide, dienochlor, with an estimated 643,281 lb (292,400 kg) applied, or 28% of the total. Only three other compounds represented more than 5% of the total use—carbaryl (498,073 lb or 22%) (226,397 kg), diazinon (326,131 lb or 14%) (148,242 kg), and propargite (143,888 lb or 6%) (65,404 kg). Of the top four products, two (dienochlor and propargite) are miticides. Together these represented 34% of the total estimated insecticide/miticide use, demonstrating the importance of mites as pests in the industry.

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Zhiguo Ju, Yousheng Duan, and Zhiqiang Ju

In China, one of the most serious problems to fruit growers is too much vegetative growth and too many pests and diseases during the growing season. Therefore, a large number of growth regulators, pesticides, and fungicides are used each year, which increases production costs and causes environmental pollution. To reduce the usage of agrochemicals, a device was invented to confine the treated area. Instead of applying chemicals directly to leaves, which may have reduced the efficiency by washing or UV degradation, the chemicals were injected directly to the truck of trees and transported through the xylem to the target organ, the leaf. Results showed that, to reach the same level of control, using plant regulators such as paclobutrazol, gibberellins, and ascorbic acid, the amount used could be reduced by 50% to 80%. The use of fungicides such as captan and diazinon could be reduced by 35% to 60%, and the use of pesticides such as vendex could be reduced by as much as 50%. Compared with the conventional method, the injection method showed three advantages: 1) It is economical in that production costs were reduced by about 40%, 2) It is efficient in that the same level of control was achieved using less chemicals (Due to the small acreage cultivated by family growers in China, the device could be installed within days and chemicals could be applied within hours.), 3) It is environmentally friendly because chemicals were not released throughout the orchard.