15diimide in 40 ml. of dichloromethane was added dropwise over a 3O-min. period. The resetion mixture was stirred at room temperature for 24 hr., followed by removal of the precipitated N,N'dicyclohexylm by filtration. The filtrate was concentmted by dietillation and the residue was dissolved in benzene, and p d through a column ( 1 ' X 1 0 ' ) of Florisil in benzene. The product, yelloworange crystals, m.p. 37-40', weighed 39 g. (100%) and exhibited a carbonyl absorption at 1790 em.-' in the infrared spectrum of a melted film. A d . Calcd. for CIIH&N: C, 70.58; H, 4.85; N, 7.48. Found: C, 70.85; H, 5.02; N, 7.54. N-(o-Chlozsphenyl)iso"ide. To a slurry of 45 g. (0.2 mole) of N-(o-chlorophenyl)"ic acid in 1 1. of dichlore methane, a solution of 41.2 g. (0.2 mole) of N,N'-dicycl+ hexylearbodiimide in 40 ml. of dichloromethane was added dropwise over a Sin. period. The mixture was stirred at room temperature for 24 hr., followed by filtration of the N,N'-dicyclohexylurea and distillation of the solvent under reduced pressure. The residue in benzene was passed through a column of Florid and the eluates were concentrated to yield 40 g. (97%) of yellow cry&&, m.p. 60-66". Recrystdlization of a sample from 1:1 benzenepetroleum ether @.p. 39-54') gave an analytical sample, m.p 65-67'. A d . Calcd. for CloH&tNCl: C, 57.85; H, 2.91; N, 6.75. Found: C, 58.35; H, 2.73; N, 6.58. The infrared spectrum of a liquid f i l m showed strong carbonyl absorption at 1800 an.-' I 8 -h of N-n-lnbtyliaomaleimide to N-n-hiyl-"ide. A solution of 5.0 g. (0.033 mole) of N-n-butylisomaleimide, 6.06 g. (0.06 mole) of triethylamine, and 3.6 g. (0.06 mole) of acetic acid in 100 ml. of benzene was heated a t reflux for 90 min. The solution was cooled, washed with water, dilute d u m hydroxide solution, and again with water. The bemene was removed under reduced pres-sure and the midue was distilled to yield a clear liquid, b.p. 50-55" (0.5 mm.). Vapor phase chromatographic analysis of this material showed it to be a mixture containing 40% N-n-butylisomaleimide, 59.4% N-n-butylmaleimide and 0.6% of an unknown impurity. The recovery Isomerization of N-phen&aom&imide to N -p h e n y l d eimide. A mixture of 5.0 g. (0.029 mole) of N-phenylisomaleimide, 1.0 g. (0.012 mole) of anhydrous d u m acetate and 15 ml. of acetic anhydride was heated on the steam bath for 1 hr. After the mixture had cooled to 2 5 O , it was poured into 100 ml. of water causing long, yellow needles to separate. These were collected and dried, 4.5 g. (90%) m.p. 90-91'. A mixture melting point with an authentic sample of N-phenylmaleimide was undepressed. When d u m acetate was absent in this reaction, the starting material was recovered.
The plant pathogenic fungusColletotrichum coccodes(Cc) and the plant growth regulator thidiazuron (TDZ) were evaluated in Maryland and Quebec for velvetleaf control in ‘Williams' and ‘Maple Arrow’ soybean. TDZ was applied at 0, 0.1, 0.2, 0.3, and 0.4 kg ai/ha alone or was combined with Cc at 109spores/m2when velvetleaf was at the 1- to 2-leaf (Trial 1) or 4- to 6-leaf (Trial 2) growth stages. Velvetleaf control increased with TDZ rate, and TDZ combined with Cc further increased control. TDZ reduced velvetleaf biomass and height, and Cc increased velvetleaf mortality. In Quebec, Cc also reduced the biomass of velvetleaf treated in Trial 1 and interacted positively with TDZ at this growth stage. Cc nearly halved the rates of TDZ required for 90 and 75% mortality of velvetleaf treated at the 1- to 2-leaf and 4- to 6-leaf stages to 0.09 and 0.12 kg/ha, respectively, in Quebec. Cc similarly lowered the rate of TDZ required for 75% stand reduction of velvetleaf in Trial 1 to 0.17 kg/ha in Maryland. Cool wet weather in Quebec contrasted with warm, dry weather in Maryland. Soybean biomass and yield were increased significantly by treatment with TDZ plus Cc in Trial 1 at both locations.
Acalymma vittatum (F.) is the primary insect pest of fresh-market cucumber and melon crops in much of the eastern United States because of their herbivory and interactions with several diseases, most notably bacterial wilt. A study was conducted to determine how soil management affects viability and infectivity of an entomopathogenic nematode that may be used for the control of A. vittatum. Dose-mortality curves under laboratory conditions suggested several Steinernema spp. as potential biocontrol agents. Field injections combined with soil bioassays showed that Steinernema riobravis Cabanillas, Poinar & Raulston (Rhabditus: Steinernematidae) longevity exceeded A. vittatum immature development time in both conventional and organic soil management systems. Mean root length densities of cucumbers increased in both soil management systems with the inclusion of nematodes. Soil management alone also influenced A. vittatum larval survivorship, with higher survival rates in the organic compared with the conventional soil management system. A 50% reduction in A. vittatum larval survival rates in both soil management systems, as determined by adult A. vittatum emergence, demonstrated the potential of incorporation of entomopathogenic nematodes for integrated pest management of diabroticites in commercial cucumber production.
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