Search

Purpose The authors aim to analyze the incidence, characteristics, surgical management, and outcome of patients presenting to St Thomas' Hospital with a rhegmatogenous retinal detachment secondary to atrophic round retinal holes.Methods This is a retrospective collation of patients presenting to a single surgeon with a round hole–associated retinal detachment between 2001 and 2009. Specific collation of demographics, retinal detachment features, choice of management, complications, requirement for further surgery, and ultimate surgical success with final visual acuity is reported.Results Fifty-six patients with a retinal detachment secondary to a round hole were identified (4.49% incidence). The cohort had a median age of 28.9 years (range 14 to 39) and a female predominance (64%). The median spherical equivalent refractive error was −5.5 diopters (range −1 to −18). The commonest quadrant with retinal holes was the inferotemporal quadrant (40% of patients). Approximately half of our cohort were identified to have lattice degeneration at any site and in either eye. The majority of patients received an external nondrainage procedure (92%) with cryotherapy (88%) and an explant (94%). Three patients required further surgery to achieve retinal reattachment and 12% required surgery for a retinal detachment in the fellow eye. At final follow-up, 78% achieved a visual acuity of 0.18 logMAR (6/12 Snellen) or better and the median final visual acuity was 0.00 logMAR (6/6 Snellen).Conclusions Retinal detachments secondary to round holes have consistent characteristic features (young, myopic, female, inferior detachment). Surgical management is increasingly advocated and most achieve primary surgical success with a good final visual acuity.

The evaluation of potato germplasm for resistance to potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a valuable component of integrated pest management; however, few attempts have been made to identify natural genetic tuber resistance to tuberworm on potato germplasm. The objective of this study was to screen potato germplasm with potential tuberworm resistance for tuber resistance under field and laboratory conditions. Experiments were conducted over a 2-yr period at the Hermiston Agricultural Research and Extension Center, Hermiston, OR. Of 125 germplasm that were tested in 2006, q13 were selected for further screening in 2007. These germplasm were: A0008-1TE, A97066LB, NY123, PA00N10-5, PA99N2, PA99N82, Paciencia, Q174-2, Russet Burbank, Rubi, Ranger Russet, Spunta G2, and T88-4. Tuber resistance of potato germplasm was determined based on the number of mines per tuber and the number of live larvae. Tubers of transgenic clone Spunta G2 were resistant to tuberworm damage. All other germplasm tested in this study, including Russet Burbank and Ranger Russet, were susceptible to tuberworm in the field and laboratory experiments. Incorporation of host plant resistance to tuber penetration by larvae together with appropriate cultural practices including limiting exposure time of tubers in the field may provide the best management option in the future.

Spatial distribution patterns of adult squash bugs were determined in watermelon, Citrullus lanatus (Thunberg) Matsumura and Nakai, during 2001 and 2002. Results of analysis using Taylor’s power law regression model indicated that squash bugs were aggregated in watermelon. Taylor’s power law provided a good fit with r 2 = 0.94. A fixed precision sequential sampling plan was developed for estimating adult squash bug density at fixed precision levels in watermelon. The plan was tested using a resampling simulation method on nine and 13 independent data sets ranging in density from 0.15 to 2.52 adult squash bugs per plant. Average estimated means obtained in 100 repeated simulation runs were within the 95% CI of the true means for all the data. Average estimated levels of precision were similar to the desired level of precision, particularly when the sampling plan was tested on data having an average mean density of 1.19 adult squash bugs per plant. Also, a sequential sampling for classifying adult squash bug density as below or above economic threshold was developed to assist in the decision-making process. The classification sampling plan is advantageous in that it requires smaller sample sizes to estimate the population status when the population density differs greatly from the action threshold. However, the plan may require excessively large sample sizes when the density is close to the threshold. Therefore, an integrated sequential sampling plan was developed using a combination of a fixed precision and classification sequential sampling plans. The integration of sampling plans can help reduce sampling requirements.

Interactions of the parasitoid Lysiphlebus testaceipes (Cresson) and the greenbug, Schizaphis graminum (Rondani), on greenbug-resistant “Cargill 607E’ (antibiosis), “Cargill 797’ (primarily tolerance), and -susceptible “Golden Harvest 510B’ sorghum, Sorghum bicolor (L.) Moench, were tested using three levels of biotype I greenbug infestation. The parasitoid infestation rate was 0.5 female and 1.0 male L. testaceipes per plant. For all three greenbug infestation levels, the parasitoid brought the greenbug under control (i.e., prevented the greenbugs from killing the plants) on both resistant hybrids, but it did not prevent heavy leaf damage at the higher greenbug infestation rates. At the low greenbug infestation rate (50 greenbugs per resistant plant when parasitoids were introduced), greenbugs damaged 5 and 18% of the total leaf area on “Cargill 797’ and “Cargill 607E’, respectively, before greenbugs were eliminated. Leaf damage was higher for the intermediate infestation study (120 greenbugs per plant), 21% and 30% leaf area were damaged on the resistant sorghum hybrids “Cargill 797’ and “Cargill 607E’, respectively. At the high greenbug infestation rate (300 greenbugs per plant), heavy damage occurred: 61% on “Cargill 607E’ and 75% on “Cargill 797’. The parasitoids did not control greenbugs on the susceptible sorghum hybrid “Golden Harvest 510B’. L. testaceipes provided comparable control on both greenbug-resistant hybrids. This study supports previous studies indicating that L. testaceipes is effective in controlling greenbugs on sorghum with antibiosis resistance to greenbugs. Furthermore, new information is provided indicating that L. testaceipes is also effective in controlling greenbugs on a greenbug-tolerant hybrid.

Two watermelon pest management practices, a squash trap crop and a standard recommendation using soil-applied carbofuran, were compared using large-scale field plots to assess trap crop suitability as a replacement for the standard in 2000, 2001, and 2002. In both systems, foliar insecticide applications were used to control squash bugs when populations exceeded threshold levels. During 2001 and 2002, a treatment of untreated watermelon was used. Early season adult insects, from seedling to fruit set, are most critical for watermelon. Significantly fewer early adult bugs were found on watermelon in the trap crop than in the standard recommended practice in 1 of 3 yr. In both years, significantly fewer adult squash bugs were found in watermelon in the trap crop than in untreated fields. The standard recommended practice significantly reduced adult squash bugs in watermelon compared with the untreated in 1 of 2 yr. There was no significant correlation of watermelon yield and squash bug density, indicating that squash bug densities were too low to impact yield. Although squash bugs were reduced significantly by the trap crop, marketable watermelon yields were lower in the squash trap crop than in untreated watermelon, suggesting that pest management treatments may interfere with crop productivity factors other than squash bug colonization. Results suggest that mid-season production squash bug should be managed by monitoring populations and using insecticides as needed rather than using at-plant treatment. Further research is needed to compare treatments during early-season production.