Body Mass Index Change between Pregnancies and Risk of Spontaneous Preterm Birth.

Objective Studies have reported an increased risk of spontaneous preterm birth associated with elevated prepregnancy body mass index (BMI) among nulliparous but not multiparous women. We examined whether changes in BMI and weight between pregnancies contributed to risk of preterm birth among obese (BMI > 29 kg/m(2)) women. Study Design This study utilized maternally linked California birth records of sequential singleton births between 2007 and 2010. Preterm birth was defined as 20 to 31 or 32 to 36 weeks of gestation. BMI was examined as category change and by tertile of weight change. Primary analyses included women without diabetes or hypertensive disorders; these women were compared with those without prior preterm birth, women with preterm deliveries preceded by spontaneous preterm labor, and women without any exclusions (i.e., diabetes or hypertensive disorders). Results Analyses showed that obesity was not associated with increased risk of spontaneous preterm birth among multiparous women. Women whose BMI increased had a decreased risk of spontaneous preterm birth at 32 to 36 weeks. Change in BMI or weight between pregnancies did not substantively alter results. Conclusion Among multiparous women, obesity was associated with reduced risk of spontaneous preterm delivery. This observed association is complex and may be influenced by maternal age, gestational age, placental insufficiency, and altered immune response.

First Report of Phytophthora ramorum Infecting California Red Fir in California.

In May 2005, branches originating from five separate whorls below the terminal on a single California red fir (Abies magnifica) in a mixed grand fir (Abies grandis) and Douglas-fir (Pseudotsuga menziesii) Christmas tree plantation near Los Gatos, CA displayed wilting and dieback of new shoot growth. Brown dieback, delineated by needle loss, extended 6 to 8 cm into 1-year-old and sometimes 2-year-old growth. The ~7-year-old, 1-m tall tree was located near the edge of the plantation, beneath an overstory of California bay laurel (Umbellularia californica) trees that were infected with Phytophthora ramorum. Isolations from dieback margins onto corn meal agar amended with ampicillin, rifamycin, and pimaricin (CARP) yielded hyphae and large, dark brown chlamydospores that were morphologically consistent with P. ramorum (1). Microsatellite analysis confirmed that isolates were of the NA1 lineage of P. ramorum. Isolates were deposited in the Washington State University Puyallup Phytophthora Master Collection. Dormant bareroot California red fir seedlings were obtained from the USDA Forest Service Placerville Nursery (Camino, CA) in February 2006 and planted in SC-10 super cell cones (Stuewe & Sons, Inc., Tangent, OR) in a standard greenhouse potting mix. Seedlings (average height 11 cm) were then forced to initiate bud break and new shoot elongation (0.5 to 1.5 cm) in a greenhouse at 21°C. Eight unwounded seedlings were inoculated with a zoospore suspension (4.185 × 105 zoospores/ml of sterile water) produced from 3- to 4-week-old V8 juice agar cultures of isolate WSU#106-0021 using an artist's airbrush powered by Badger Propel canned propellant. Eight control seedlings were sprayed with water alone. Seedlings were placed in plastic tubs with ~2.5 cm of warm water in the bottom to provide humidity. A plastic bag supported by a wire frame was used to cover each tub. Tubs were placed in a biocontainment unit at 15 to 16°C under 24 h of fluorescent light. The plastic was removed after 5 days and seedlings were left under the same conditions. Seven days after inoculation, 25 to 100% (average 68%) of the new shoots on each of the eight inoculated seedlings were wilted and 100% of these seedlings exhibited dark brown dieback into the 1-year-old stems (range of 1.0 to 2.3 cm, average 1.6 cm). Tissues from shoots and dieback edges were plated onto CARP media. All of these attempts resulted in successful isolation of P. ramorum, and cultures exhibited the same hyphal morphology and chlamydospore characteristics when compared with the isolate tested. Control plants did not develop symptoms. This trial completes Koch's postulates to establish California red fir as a host of Phytophthora ramorum. To our knowledge, this site contains the only reported infection of California red fir by P. ramorum. The potential for infection within its native range is unknown. Reference: (1) S. Werres et al. Mycol. Res. 105:1155, 2001.

Recovery Frequency of Phytophthora ramorum and Other Phytophthora spp. in the Soil Profile of Ornamental Retail Nurseries.

We tested the hypothesis that inoculum of the aboveground exotic plant pathogen Phytophthora ramorum would be limited to the organic layer (top layer of plant debris) of soils at infested retail nurseries located outside of the area where the pathogen has become established in the landscape. To test this hypothesis and compare inoculum levels of P. ramorum with levels of other Phytophthora spp. in the soil profile, soil cores were collected and sampled from three Washington State retail nurseries at which the soil had previously tested positive for P. ramorum. Phytophthora was isolated from soil using rhododendron leaves as bait, and pure cultures were obtained and stored on V8 juice agar. Isolates were identified to species using a combination of DNA sequencing of the internal transcribed spacer (ITS) region of rDNA, real-time polymerase chain reaction (PCR) diagnostic testing, and culture morphology. Recovery frequencies were tabulated and compared by species at the organic layer, 0 to 5 cm, 5 to 10 cm, and 10 to 15 cm depth classes. The three most common Phytophthora spp. recovered from the soil cores were P. citricola (32%), P. drechsleri (32%), and P. ramorum (27%). P. citricola and P. drechsleri were more evenly distributed throughout the soil profile, whereas P. ramorum was primarily recovered from the organic and 0 to 5 cm depth class (86% of recoveries). P. ramorum was not detected below 10 cm.