No abstract

Field experiments were conducted near Chickasha, OK, in 1999 and 2000 and near Perkins, OK, in 2000 to evaluate the effects of Palmer amaranth on harvest efficiency of grain sorghum and full-season competition with that crop. Weed densities were 0 (the weed-free check), 1, 2, 4, 6, 9, 12, and 18 plants/15 m of row. In the harvest efficiency experiments, each additional weed per 15 m of row increased grain moisture before cleaning by 0.7 and 0.2% at Chickasha in 1999 and at Perkins, respectively. After cleaning, it increased moisture by 0.2% in both the experiments for each weed. Foreign material increased 67, 2, and 3 kg/ha at Chickasha in 1999, Chickasha in 2000, and Perkins, respectively. At Chickasha in 2000, sorghum seed loss through the combine increased 11 kg/ha for each additional weed per 15 m of row. Grain grades improved at Perkins at higher weed densities. In the competition experiments, grain yield decreased by 1.8 to 3.5% for each increase of 1 weed/15 m of row. More weeds resulted in higher weed dry weight. Each kilogram of Palmer amaranth dry weight per plot reduced grain yield by 5.3 to 9.1%. In 2000, sorghum seeds per panicle were reduced by 27 to 50 for each weed. Grain grades generally decreased as weed density increased at Chickasha in 2000 but not at Perkins.

Sorghum anthracnose, caused by Colletotrichum sublineolum, is widely distributed in most grain sorghum-producing areas in Arkansas, and localized epidemics continue to occur across the state. The objectives of this research were to determine the number of pathotypes of C. sublineolum in Arkansas and to determine where these pathotypes are located within the state. Ninety-eight isolates were collected from research stations and production fields located in the Delta region of Arkansas from 2003 through 2005 and were tested for virulence to eight differential grain sorghum breeding lines. Of these, 11 isolates produced conflicting and unreliable results and were excluded from further analysis. Among the remaining 87 isolates, 13 pathotypes were identified. Eleven of these pathotypes were previously unreported, with 53% of the isolates consisting of pathotype 9. Pathotype 9 was distinguished from all other pathotypes by its virulence to all eight differential lines. Pathotype diversity appeared to be more closely associated with the year than with the locations where isolates were collected. Although all host differential lines were susceptible to at least 50% of the isolates evaluated, inbred lines SC326-6, TAM428, and TX2536 were susceptible to more than 90% of the 87 isolates evaluated. These results showed that the C. sublineolum populations in Arkansas are diverse based on the comparisons of pathogenicity to previously published host differentials, and it appears that these field populations varied from year to year.

The structures of the crystalline neutral complex of the isonicotinate ion with lanthanum(III) and of the crystalline salt of the cationic complex of nicotinic acid with holmium(III) have been determined by three-dimensional X-ray diffraction techniques. The complexes crystallize in P2l/c. The crystal parameters for Ho(C5H4NCOOH)3(H20)2Cr(NCS)6-2H20 are a = 9.578 (5) A, b = 25.954 (13) Á, c = 15.784 (7) Á, ß = 108.48 (2)°, deM = 1.797, dmtmi = 1.78 (2) g/cm3. The conventional discrepancy factor for this structure is 0.048 for 2989 diffractometer data. The crystal parameters for La-(C5H4NC00)3(H20)2 are a = 9.744 (3) Á, b = 19.908 (9) Á, c = 11.607 (4) A, ß = 68.20 (2)°, ¿caicd = 1.72, dmeasd = 1.70 (2) g/cm3. The discrepancy factor for this structure is 0.038 for 2554 diffractometer data. The primary structural units in both compounds are polymer chains made up of lanthanide(III) ions alternately linked by four and two bridging carboxylate groups. The eight coordination about each metal is completed by two water molecules. In the add complex, two additional waters and one hexaisothiocyanatochromate ion are also present. The acid ligand appears to be present as a zwitterion with the hydrogen attached to the nitrogen. These linear polymeric structures are compared with the dimeric structures found in the complexes of the rare earth metals with the nicotinate ion.Contribution prom the Department op Chemistry,

The crystal structures of the hydrated nicotinate complexes of lanthanum(III) and samarium(III) have been determined by three-dimensional X-ray diffraction techniques using Patterson and Fourier syntheses. The compounds have the empirical formula [Ln(C SH 4NC02) 3(H20)2] and crystallize in space group Fife with lattice parameters a = 9.805 (5) A,b= 12.