The Effect of Open-Ended High Tunnels in Western Washington on Late Blight and Physiological Leaf Roll Among Five Tomato Cultivars

A 3-year study in western Washington from 2010 to 2012 evaluated five tomato cultivars for tomato disease development and yield in open-ended high-tunnel versus open-field settings. Findings in 2010 revealed that severity of late blight, caused by Phytophthora infestans (US-11), was significantly (P = 0.002) lower in high-tunnel compared with open-field experimental plots based on area under disease progress curve (AUDPC) values of 0.02 versus 321, respectively. In spite of rescue foliar fungicide applications to open-field plots in 2011 and 2012, the mean number of late blight infections across cultivars was 1.8 to 30.8 compared with only 0 to 6.5 in high tunnels for these years. Furthermore, accumulated hours of leaf wetness were fewer in high tunnels than the open field each year (857 versus 1,060 in 2010, 598 versus 998 in 2011, and 885 versus 923 in 2012). Cultivar susceptibility to late blight could not be differentiated in high tunnels due to low disease pressure. However, all five cultivars proved susceptible in the open field, with 'Oregon Spring' consistently having the most lesions. In contrast, high-tunnel production contributed to an increased severity of physiological leaf roll compared with open-field production each year, and these values differed significantly (P = 0.0335 and 0.0252) in 2011 and 2012, respectively. AUDPC values for physiological leaf roll showed that Oregon Spring was significantly (P = <0.0001) less susceptible than other cultivars each year. Physiological leaf roll correlated positively (r values of 0.758 to 0. 960) and significantly (P < 0.05) with leaf wetness and air temperature in all years in both high-tunnel and open-field settings but the same was not true for relative humidity. Even with severe physiological leaf roll, high-tunnel production in 2010 resulted in significantly (P < 0.0001) greater total tomato yield than open-field production (35.0 versus 10.6 t ha^-1). Although a significant interaction between production system and cultivar occurred in 2011 and 2012, tomato yield always was greater in high-tunnel than open-field plots. Open-ended high tunnels offer tomato growers a potential tool for managing late blight in western Washington while also increasing yield, and could be especially useful in organic production.

First Report of Tomato Pith Necrosis (Pseudomonas corrugata) on Tomato (Solanum lycopersicum) in Washington

Tomato pith necrosis was observed on 2.7% of tomatoes grown in rows covered with black polyethylene, various biodegradable plastics, and an experimental spunbond poly(lactic) acid agricultural mulch in high tunnel and open field experimental plots, in western Washington in 2011. Symptoms developed on 3-month-old plants and progressed acropetally until night temperatures dropped to 10°C. Affected plants had chlorotic leaves, produced adventitious roots, and pith tissue was brown and either corrugated or rotted. Similar symptoms were observed again in 2012 on 2.0% of plants, but only in experimental plots with black polyethylene mulch. Diseased stem tissue was homogenized with a mortar and pestle in sterile water and the extract was streaked onto King's medium B (KMB) agar. Colonies were white and smooth initially, and after 5 days had an irregular surface and margin and produced a tan diffuse pigment. One isolate, Pc.Sl.2011, was gram-negative, grew at 37°C on nutrient broth yeast (NBY) agar, did not fluoresce on KMB (3), and was arginine dihydrolase positive. A partial 16S fragment, 1,387 bp, was obtained via PCR with universal 27f and 1492f primers. The resulting sequence exhibited 99% identity to Pseudomonas corrugata Roberts & Scarlett, and has been assigned GenBank Accession KC812729. Pathogenicity of Pc.Sl.2011 was tested in two greenhouse trials with five replications of one tomato plant per treatment. Seeds of 'Celebrity' were surface sterilized by soaking in 70% EtOH for 30 s and then 10% NaOCl for 30 s, then rinsed with sterile water and sown into 14 cm diameter pots filled with non-sterile Sunshine Mix #1 (SunGro Horticulture Distribution Inc., Bellevue, WA). Seedlings were inoculated at the four leaf stage using 5 ml NBY broth cultures of Pc.Sl.2011 grown at 28°C for 12 h with agitation. A sterile needle was used to inject 10 μl of either sterile water or a bacterial suspension of 1.0 × 10¹⁰ CFU/ml into the axil of the second true leaf. Inoculum concentration was confirmed by NBY dilution plate counts. The plants were incubated in clear polyethylene bags for 4 days and placed in a greenhouse at 21.1 ± 1.2°C with a 14-h photoperiod. The first and second trials were sampled at 8 and 9 weeks after inoculation, respectively. Plants inoculated with sterile water had green pith tissue. However, 60 and 40% of inoculated plants had brown pith tissue around the inoculation site in the first and second trial, respectively, but wilting and adventitious roots were not observed. Stem tissue from the inoculation site of symptomatic plants was homogenized as above, and the extract streaked onto NBY agar plates. Three isolates recovered from inoculated plants from both trials had the same characteristics as the original isolate, including similar colony morphology, ability to grow on NBY at 37°C, and lack of fluorescence on KMB. To our knowledge, this is the first documented report of tomato pith necrosis in Washington. Pith necrosis has been reported previously in high tunnel tomato production (4), where excess nitrogen fertilization occurs with cool evening temperatures (3), and when plastic mulch is utilized (2). In the cool climate of western Washington, successful tomato production requires the use of agricultural mulches and covers that trap heat. Since P. corrugata has been isolated from soil and the tomato seeds of inoculated plants (1), local growers attempting to manage pith necrosis need to select tomato seed lots carefully and avoid applying excess nitrogen, especially when using plastic mulch. References: (1) V. Catara. Mol. Plant Pathol. 8:233, 2007. (2) E. J. Sikora and W. S. Gazaway. Online. ACES.edu ANR-0797, 2009. (3) C. M. Scarlett and J. T. Fletcher. Ann. Appl. Biol. 88:105, 1978. (4) X. Xu et al. Plant Dis. 97:988, 2013.

First Report of Verticillium Wilt on Lettuce (Lactuca sativa) in Washington Caused by Verticillium tricorpus

Symptoms of Verticillium wilt were observed on lettuce (Lactuca sativa L.) harvested from high tunnel and open field experimental plots in annual, consecutive spring plantings in western Washington from 2010 to 2012. Leaves had v-shaped, chlorotic lesions, and yellow or brown vascular tissue was noted in the crowns. Total disease incidence increased from 0.2% in 2010 to 1.9% in 2011 and to 14.4% in 2012. Verticillium spp. obtained from infected crown tissues and cultured on half-strength potato dextrose agar medium produced yellow pigment, black microsclerotia, white mycelia, tan chlamydospores, and uniseptate conidia averaging 10.6 × 3.7 μm. Isolates were identified tentatively as Verticillium tricorpus I. (3). Three isolates, Vt.Ls.2010, Vt.Ls.2011-1, and Vt.Ls.2011-2, were evaluated for pathogenicity on 4-week-old 'Coastal Star' seedlings in two greenhouse trials. In Trial I, four replicates of two duplicate plants per each isolate, and in Trial II, five replicates of one plant per each isolate were inoculated with conidial suspensions adjusted to 2.0 × 10⁶ and 5.0 × 10⁶ conidia/ml, respectively. Additionally, in each trial, two sets of control treatments of five plants each were inoculated with either an isolate of V. dahliae at the same conidial concentration or with sterile water. Root tips were cut and exposed to the suspensions for 5 s, then seedlings were transplanted into Sunshine Mix #1 (SunGro Horticulture Distribution Inc., Bellevue, WA), and kept in a greenhouse at 17.7 ± 3.4°C. Plants were harvested 8 to 9 weeks post-inoculation, and symptoms were rated visually. Vt.Ls.2010, Vt.Ls.2011-1, and Vt.Ls.2011-2 caused chlorosis and vascular discoloration on 25, 13, and 13% of the plants in Trial I; and 40, 60, and 20% of plants in Trial II, respectively. V. dahliae caused similar symptoms on 25 and 40% of the plants in the two trials, respectively, but these plants had greater intensity and length of vascular discoloration compared with the three test isolates. None of the water control plants were symptomatic. All V. tricorpus isolates were recovered from inoculated plants, and colony morphologies were similar to the original isolates. The internal transcribed spacer (ITS) rDNA of isolate Vt.Ls.2010 was amplified with ITS4 and ITS6 primer sets. ITS rDNA sequences between Vt.Ls.2010 and two isolates of V. tricorpus in GenBank (Accession Nos. FJ900211 and AB353343) were 100% identical. V. tricorpus is considered a weak pathogen of lettuce crops in California (2), but authors in Japan recently reported pathogenic isolates of V. tricorpus on lettuce (4). To our knowledge, this is the first report of Verticillium wilt caused by V. tricorpus in Washington. Lettuce is the number two crop grown in high tunnels in the United States (1), and cropping lettuce continuously in them can increase the risk of this and other soilborne pathogens. References: (1) E. E. Carey et al. HortTechnology 19:37, 2009. (2) Q.-M. Qin et al. Plant Dis. 92:69, 2008. (3) H. C. Smith. N. Z. J. Agric. Res. 8:450, 1965. (4) T. Usami et al. J. Gen. Plant Pathol. 77:17, 2010.

Prevalence of the use of herbal products in a low-income population

OBJECTIVES

This study determined the prevalence of herb/supplement use in a low-income population and determined the providers' level of knowledge about herbs/supplements.

METHODS

Adult English-speaking patients seen at a rural family practice residency clinic were offered an anonymous survey. Another survey was developed for the clinic providers. Data were analyzed using the chi-square test.

RESULTS

Fifty-six percent of a low-income population use herbs/supplements; 41% of all users cited friends or relatives as their main source of information, and 53% of users had not informed their provider. In the provider survey, 69% of the providers indicated that they had received no education about herbs/supplements, yet 71% were asked about them by patients at least twice a month.

CONCLUSIONS

Because herb/supplement use occurs across all demographic groups, all patients should be questioned about their use of such substances. Currently, few providers are prepared to guide their patients about herbs/supplements. Efforts should be made to educate health care providers about common herbs/supplements.

[Pleural exudate and intestinal obstruction. Late manifestation of traumatic diaphragmatic hernia]

The diagnosis of diaphragmatic rupture is most commonly made during surgical exploration following penetrating injuries, or in the presence of obvious herniation of viscera through the diaphragm. In the absence of acute herniation a diaphragmatic rupture frequently remains unrecognized and may cause herniation of intra-abdominal contents into the thorax after latency periods of up to several decades. Therefore diaphragmatic rupture is an important differential diagnosis in subjects with unclear abdominal conditions or unexplained pleural effusion in the presence of a history of previous thoracoabdominal trauma. A case is presented which highlights pitfalls and clinical findings.

[Myasthenia gravis and thymoma]

The article reviews age, symptoms, diagnosis, response to thymectomy, survival and concomitant disease in 15 patients with myasthenia gravis and thymoma registered in the period 1947-87. The thymomas were locally asymptomatic. The combination of roentgenological investigation and serological detection of nonreceptor muscle antibodies indicated the presence of a thymoma in 13 out of 14 patients. In eight out of nine patients with benign thymomas, myasthenic symptoms improved after thymectomy. Six out of eight patients with noninvasive thymomas survived five years, as opposed to one out of four with invasive thymomas. Associated disorders included polymyositis, myocarditis, parkinsonism and amnesia.