In 1996 a common sunflower population near Howard, SD, was suspected to be cross-resistant to imazethapyr and chlorimuron. Whole-plant acetolactate synthase (ALS) assays confirmed ALS-inhibitor resistance in the Howard biotype. The I 50 values (inhibition of 50% of the enzyme activity) indicated that the resistant population required 39 and 9 times more imazethapyr and chlorimuron, respectively, to obtain the same level of enzyme inhibition compared with the sensitive biotype. Herbicide dose response data supported the whole-plant enzyme assay data; control (> 90%) was not achieved with less than a four-times application rate of chlorimuron. Control with imazethapyr was not achieved even with a 16-times rate. Chlorimuron and imazethapyr controlled 70 and 95% of the population, respectively, when a four-times rate of each herbicide was applied separately. Differences in 14C-herbicide absorption were observed, suggesting that there may be physical or chemical differences in leaf surface composition between the resistant and sensitive biotypes. Although translocation of 14C-herbicide was less in the resistant biotype than in the sensitive biotype, the differences were not enough to explain chlorimuron and imazethapyr selectivity between the two biotypes. Overall results suggested that the differences in the common sunflower populations were attributed to an altered site of action on the ALS enzyme.

Relationships among weed seed rain, soil seedbank, and seedling recruitment in no-tillage systems were studied from July 1993 to May 1996. Multiple regression analysis indicated that seedling recruitment of only six of the 25 weed species present was correlated with seed rain samples from the previous autumn, spring soil seedbank samples, or a combination of the two. However, seedling recruitment of the dominant annual grasses (yellow foxtail, giant foxtail, and fall panicum in Field 1–1994, Field 2–1995, and Field 3–1996, respectively) was related to seedbank populations or a combination of seedbank and seed rain densities. These grasses accounted for at least 32% of the emerged seedlings, 12 to 78% of the seedbank, and 16 to 77% of the seed rain. Seedling recruitment of large crabgrass and two broadleaf species, Virginia copperleaf and wild carrot, also were described by seedbank densities or a combination of seedbank and seed rain densities. However, both the broadleaf species were minor components of the cropping system, representing ≤ 4% of all seedlings. In each year, the sum of all weeds in the seedbank exceeded 1,300 seeds m−2 (0 to 10 cm deep). The fraction of the total seedbank that emerged each year ranged from 3 to 17%, but there was great variability among species. The aforementioned dominant grasses ranged in emergence from 3 to 25% of their seedbanks. Emergence of other species ranged from a low of 1% for common lambsquarters up to 41% for large crabgrass. Prediction of seedling recruitment from seed rain or seedbank densities was variable; however, combining both components improved the fit of regression describing seedling recruitment.

Both angiotensin converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs can lead to functional renal insufficiency. In an observational study we assessed the frequency of this adverse effect in patients aged over 75 years receiving these drugs in combination. In one year, out of 1500 patients whose records were screened, 12 were prescribed this combination. 2 developed acute renal failure, of whom one died and the other recovered after discontinuation of both drugs. 4 patients showed deterioration in renal function, which returned to normal after one of the drugs was stopped. Renal function remained stable in 6 patients: patients with deterioration in renal function were older and more likely to be on diuretics. This drug combination is commonly nephrotoxic in the elderly and should be avoided, especially in those taking diuretics.

A common sunflower population from Howard, SD (HSD) was previously determined to be cross-resistant to imazethapyr and chlorimuron-ethyl, both acetolactate synthase–inhibiting (ALS) herbicides. Experiments were conducted to determine if target-site polymorphisms could act as a mechanism of ALS-inhibitor herbicide resistance in the HSD common sunflower. Approximately 1,600 nucleotides were amplified by polymerase chain reaction and sequenced from putativeALSgene(s) in common sunflower and Jerusalem artichoke. In sunflower, two different amplification products were detected that differed by a nine-basepair deletion. This suggested the presence of at least two ALS genes in common sunflower that could contribute to the herbicide resistance phenotype. In addition, an Ala205to Val205substitution was observed in several clones from resistant common sunflower (amino acid position is relative to the full-length mouse-ear cress ALS protein). Previously documented mutations at this position in other species indicated that it might play a vital role in conferring resistance to one or more ALS-inhibitor herbicides.