Psychomotor and cognitive effects of a single oral dose of talnetant (SB223412) in healthy volunteers compared with placebo or haloperidol.

Central Nervous System (CNS) effects of talnetant, an NK-3 antagonist in development for schizophrenia, were compared to those of haloperidol and placebo. The study was randomised, double-blind, three-way crossover of talnetant 200 mg, haloperidol 3 mg or placebo. Twelve healthy males participated and EEG, saccadic and smooth pursuit eye movements, adaptive tracking, body sway, finger tapping, hormones, visual analogue scales (VAS) for alertness, mood and calmness and psychedelic effects, left/right distraction task, Tower of London and Visual and Verbal Learning Task were assessed. Haloperidol showed (difference to placebo; 95% CI; p-value) decreases in EEG alpha power (-0.87microV; -1.51/-0.22; p = 0.0110), saccadic inaccuracy (2.0%; 0.5/3.6; p = 0.0133), smooth pursuit eye movements (-7.5%; -12.0/-3.0; p = 0.0026), adaptive tracking (-3.5%; -5.4/-1.7; p = 0.0009), alertness (-6.8 mm; -11.1/-2.4; p = 0.0039), negative mood (-4.6 mm; -8.6/-0.6; p = 0.0266), the ability to control thoughts (1.2 mm; 0.2/2.3; p = 0.0214), and an increase of serum prolactin (ratio 4.1; 3.0/5.6; p < 0.0001). Talnetant showed decreased alpha power (-0.69 muV; -1.34/-0.04; p = 0.0390), improved adaptive tracking (1.9%; 0.1/3.7; p = 0.0370) and reduced calmness on VAS Bond and Lader (-4.5 mm; -8.0/-1.0; p = 0.0151). Haloperidol effects were predominantly CNS-depressant, while those of talnetant were slightly stimulatory. The results suggest that talnetant penetrates the brain, but it remains to be established whether this dose is sufficient and whether the observed effect profile is class-specific for NK3-antagonists.

Influence of Late Season Harvesting, Fall Grazing, and Fungicide Treatment on Verticillium Wilt Incidence, Plant Density, and Forage Yield of Alfalfa.

Studies were conducted in the presence of Verticillium wilt (Verticillium albo-atrum) to determine the effect of fall harvesting and grazing over time on plant stand and forage yield of alfalfa (Medicago sativa). Resistant and susceptible cultivars were tested on established and newly seeded fields. In the fall (experiments 1 and 2), cultivars were either: (i) cut (third time); (ii) grazed; (iii) cut and grazed; or (iv) left uncut and ungrazed. Although Verticillium was present, test sites for experiments 2 and 3 were sprayed with a spore suspension of V. albo-atrum immediately following the first cutting of each experiment to standardize disease pressure. In experiment 1, the moderately resistant cultivar Apollo II, harvested twice without a late third cutting or fall grazing, produced the highest forage yield the following year. Fall grazing reduced subsequent yields in both the 2- and 3-cut treatments. In experiment 2, a third cutting decreased plant density and forage yield in both resistant and susceptible cultivars, while grazing had no effect. Neither fall treatment affected incidence of Verticillium wilt. In experiment 3, application of the fungicide benomyl to plant stubble following each harvest decreased Verticillium wilt in Apollo but not in Arrow. Overall, with the resistant cultivar Arrow, harvesting twice annually and grazing after a killing frost in lieu of late fall cutting slowed disease development, prolonged stand life, and maximized forage yield and quality.

A Rapid Method Using PCR-Based SCAR Markers for the Detection and Identification of Phoma sclerotioides: The Cause of Brown Root Rot Disease of Alfalfa.

A rapid technique for identification and detection of Phoma sclerotioides, the causal agent of brown root rot of alfalfa, has been developed using polymerase chain reaction (PCR). Amplification products obtained from random amplified polymorphic DNA (RAPD) reactions were cloned and sequenced, and two extended primer sets were designed from the resulting data that were used to detect sequence-characterized DNA markers. A single 499-bp DNA amplification product was consistently obtained from primers PSB12499 that was specific for 19 isolates of P.sclerotioides but was not produced from Phoma medicaginis or Phoma betae, or from other soilborne pathogens including Aphanomyces euteiches, Rhizoctonia solani, Fusarium oxysporum, Pythium ultimum, or Phytophthora infestans. A 499-bp amplification product was also produced from root tissue known to be infected with the fungus as verified by microscopic examination. A similar PCR product was obtained from soil samples collected from fields with an established infection of P. sclerotioides on alfalfa. This PCR-based assay enables detection of P. sclerotioides from alfalfa root tissue and in soil samples in a single day, including extraction of DNA, compared with standard methods that require up to 100 days for identification using agar media.

Seasonal Fluctuations of Soil and Tissue Populations of Ditylenchus dipsaci and Aphelenchoides ritzemabosi in Alfalfa.

Population dynamics of A. ritzemabosi and D. dipsaci were studied in two alfalfa fields in Wyoming. Symptomatic stem-bud tissue and root-zone soil from alfalfa plants exhibiting symptoms of D. dipsaci infection were collected at intervals of 3 to 4 weeks. Both nematodes were extracted from stem tissue with the Baermann funnel method and from soil with the sieving and Baermann funnel method. Soil moisture and soil temperature at 5 cm accounted for 64.8% and 61.0%, respectively, of the variability in numbers of both nematodes in soil at the Big Horn field. Also at the Big Horn field, A. ritzemabosi was found in soil on only three of the 14 collection dates, whereas D. dipsaci was found in soil on 12 dates. Aphelenchoides ritzemabosi was found in stem tissue samples on 9 of the 14 sampling dates whereas D. dipsaci was found on all dates. Populations of both nematodes in stem tissue peaked in October, and soil populations of both peaked in January, when soil moisture was greatest. Numbers of D. dipsaci in stem tissue were related to mean air temperature 3 weeks prior to tissue collection, while none of the climatic factors measured were associated with numbers of A. ritzemabosi. At the Dayton field, soil moisture plus soil temperature at 5 cm accounted for 98.2% and 91.4% of the variability in the soil populations of A. ritzemabosi and D. dipsaci, respectively. Aphelenchoides ritzemabosi was extracted from soil at two of the five collection dates, compared to extraction of D. dipsaci at three dates. Aphelenchoides ritzemabosi was collected from stem tissue at six of the seven sampling dates while D. dipsaci was found at all sampling dates. The only environmental factor that was associated with an increase in the numbers of both nematodes in alfalfa stem tissue was total precipitation 1 week prior to sampling, and this occurred only at the Dayton field. Numbers of A. ritzemabosi in stem tissue appeared to be not affected by any of the environmental factors studied, while numbers of D. dipsaci in stem tissue were associated with cumulative monthly precipitation, snow cover at time of sampling, and the mean weekly temperature 3 weeks prior to sampling. Harvesting alfalfa reduced the numbers of A. ritzemabosi at the Big Horn field and both nematodes at the Dayton field.

First Report of Brown Root Rot on Alfalfa Caused by Phoma sclerotioides in the Continental United States.

Phoma sclerotioides G. Preuss ex Sacc. (previously named Plenodomus meliloti Dearn. & G.B. Sanford) is associated with root rot and extensive winterkill of leguminous forage crops, such as clover (Trifolium and Melilotus spp.), sainfoin (Onobrychis viciifolia), and alfalfa (Medicago sativa). Winterkill and root rot of irrigated alfalfa were observed for the first time in a field of cv. Multiplier in western Wyoming during the spring of 1996. Dark brown to black, sunken, rotting lesions were noted on upper secondary roots and taproots of dead and living diseased plants. Superficial and embedded beaked pycnidia and pycnosclerotia were observed near root lesions. A Phoma sp. isolated from a diseased plant in Farson, WY, was maintained on potato dextrose and half-strength V8-juice agars. Beaked pycnidia, typical of P. sclerotioides, were observed in culture when grown at 10°C for 2 months. A pathogenicity test was performed on cv. Multiplier. Two barley seeds colonized by a Phoma sp. derived from a Wyoming isolate were positioned on taproots of healthy, greenhouse-grown, 5-month-old plants ≈2.5 cm below the crown and were covered with a small piece of sterile cotton. Three replicate samples (24 plants inoculated and 24 plants uninoculated per replicate) were winter-hardened for 4 weeks (15.6°C/10°C, day/night, for 2 weeks, followed by 10°C/7.2°C, day/night, for 2 weeks) and placed outside during January 1998 in Laramie, WY, for a 4-month winter exposure period. Plants were rated for disease during June 1998. A disease severity rating of 1 to 5 was assigned to each experimental unit, where 1 = no disease and 5 = dead plant. The percentage of diseased plants at each severity rating for all inoculated plants was 1 = 19%, 2 = 33%, 3 = 31%, 4 = 13%, and 5 = 4%. Mycelium typical of P. sclerotioides was found on 99% of inoculated plant roots whether or not they had pycnidia. Pycnidia were found on the lower stems and petioles of some inoculated plants. Three percent of control plants also developed brown root rot (BRR) symptoms (taproot lesions or discoloration) by June 1998. The percentage of diseased plants at each severity rating for all uninoculated plants was 1 = 96%, 2 = 4%, and 3 through 5 = 0%. Aboveground propagule placement likely contributed to the spread of BRR by raindrop splash and wind-driven plant debris to adjacent alfalfa. Most inoculated plants had immature pycnidia or protopycnidia (94%), whereas 6.9% of the plants also had fully mature, beaked pycnidia. Pure fungal cultures were obtained from several diseased roots and compared with the original Wyoming Phoma sp. culture and a Canada isolate of P. sclerotioides (ATCC no. 56515) (2): colony, pycnidial, and conidial morphologies were identical, completing Koch's postulates. This is the first report of BRR on alfalfa in the continental United States. References: (1) J. G. N. Davidson. 1990. Brown root rot. Pages 29-31 in: Compendium of Alfalfa Disease. 2nd ed. The American Phytopathological Society, St. Paul, MN. (2) C. R. Hollingsworth et al. Phytopathology 88(suppl.):S39, 1999.

Biological Relationship of Meloidogyne hapla Populations to Alfalfa Cultivars.

Greenhouse and growth chamber studies were established to determine if there are pathological and physiological differences among Meloidogyne hapla populations from California (CA), Nevada (NV), Utah (UT), and Wyoming (WY) on alfalfa cultivars classified as resistant or susceptible to root-knot nematodes. In the greenhouse, plant survival was not consistent with resistance classifications. While all highly resistant Nevada Synthetic germplasm (Nev Syn XX) plants survived inoculation with all nematode populations, two cultivars classified as moderately resistant ('Chief' and 'Kingstar') survived (P

Distribution in the Western United States on Alfalfa and Cultivar Reaction to Mixed Populations of Ditylenchus dipsaci and Aphelenchoides ritzemabosi.

Ditylenchus dipsaci and Aphelenchoides ritzemabosi were extracted from 29 of 40 plant samples (72.5%) collected from Arizona, California, Colorado, Idaho, Montana, Oregon, South Dakota, Utah, Washington, and Wyoming. Percentages of A. ritzemabosi in tissue of the 29 samples ranged from 1.77 to 67.82%. Only Ditylenchus dipsaci was recovered from the remaining 11 samples. All of the 16 fields sampled in Wyoming contained both nematodes. Percentages of A. ritzemabosi in the Wyoming samples ranged from 0.7-30.0%, with an overall mean of 10.3%. Individual plants collected from a field in Big Horn, Wyoming, all contained both nematodes. Percentages of A. ritzemabosi in tissue ranged from 5-70%. Alfalfa stem nematode symptomatic plants in 17 of 18 alfalfa cultivars collected from a screening nursery in California contained both nematodes, of which 10-94% were A. ritzemabosi. Only one cultivar had D. dipsaci only, and no entries had A. ritzemabosi only. Under environmentally controlled conditions, A. ritzemabosi reproduced in all nine alfalfa cultivars tested at 6 weeks of age with a mean reproductive factor (final population/initial population) of 4.1. There were more (P

Biology and Pathogenicity of Pratylenchus neglectus on Alfalfa.

Pratylenchus neglectus reduced the growth of alfalfa cultivars in greenhouse and growth chamber studies. Inocula (1,000, 5,000 and 10,000 nematodes per plant) reduced shoot dry weights of Ranger by 16, 27, and 40%, of Lahontan by 16, 32, and 40%, and of Nevada Synthetic XX (Nev Syn XX) by 18, 26, and 37%, respectively, at 26 ñ 2 C. Pratylenchus neglectus at 1,000 nematodes per plant reduced Ranger shoot dry weights by 5, 12, 18, and 27%, at 15, 20, 25, and 30 C, respectively, whereas 5,000 nematodes per plant reduced shoot dry weights by 12, 17, 26, and 38%, respectively, at similar temperatures. Reductions in dry root weights were directly related to reductions in shoot growth. At 1,000 nematodes per plant, Ranger root dry weights were reduced by 3, 14, 40, and 40%, whereas 5,000 nematodes per plant reduced root dry weight by 25, 31, 59, and 63%, respectively, at similar temperatures. Similar results were observed on Lahontan and Nev Syn XX at the same inoculum levels and soil temperatures. Nematode reproductive indices (final nematode population per plant divided by initial nematode inoculum per plant) were higher at 1,000 nematodes per plant than at 5,000 nematodes per plant, were positively correlated with temperature, and were unaffected by cultivar.

Pathogenicity of Two Populations of Meloidogyne hapla Chitwood on Alfalfa and Sainfoin.

The pathogenicity of two populations of the northern root-knot nematode, Meloidogyne hapla Chitwood, population 1 (P1) from alfalfa and population 2 (P2) from sainfoin, was studied on both alfalfa and sainfoin for 25 weeks. Alfalfa and sainfoin plants inoculated with P2 had significantly (P

A Nematicide Seed Treatment to Control Ditylenchus dipsaci on Seedling Alfalfa.

Three nematicides were evaluated as seed treatments to control the alfalfa stem nematode (Ditylenchus dipsaci) on seedling alfalfa. Alfalfa seeds were soaked for 10 hours in a 0.5% (formulated by weight) concentration of either carbofuran, phenamiphos or oxamyl in acetone with no adverse effect on seed germination. All three treatments decreased nematode damage and increased survival of 'Ranger' (susceptible) and 'Lahontan' (resistant) alfalfa plants, when seeds were planted in soil infested with D. dipsaci. Mean live plant counts after 6 weeks in the untreated control, acetone alone, carbofuran, phenamiphos, and oxamyl treatments, respectively, were 4.3, 6.3, 19.0, 19.8, and 19.0 for Lahontan and 4.5, 1.5, 18.5, 19.3, and 18.0 for Ranger from 20 seeds/pot. Nematicide seed treatments resulted in significantly healthier Ranger alfalfa plants 4 months after planting. The combination of seed treatment and host resistance may provide a means of establishing alfalfa in an alfalfa monocropped system where soil populations of D. dipsaci are high.

Evaluation of Cultivars, Experimental Lines and Plant Introduction Collection of Sainfoin for Resistance to Meloidogyne hapla Chitwood.

Stands of several cultivars and experimental lines of sainfoin (Onobrychis viciifolia) were severely reduced (92% average loss) in a field naturally infested with Meloidogyne hapla. Stands of two alfalfa cultivars included in the test were unaffected. In studies conducted in the greenhouse with plants inoculated at the time of seeding, average mortality was 55% for sainfoin entries and 7% for Ladak alfalfa. Little mortality occurred when plants were inoculated after establishment. Three months after inoculation, all sainfoin entries were heavily galled (range of 3.3-3.7 on a scale of 1-4) while roots of Ladak were only slightly galled (rating of 1.6). Intermating of plants selected in the field plots for resistance to M. hapla showed a slight increase in resistance. Of the 147 plant introduction lines tested in the greenhouse, none were resistant to M. hapla.

Effect of Ditylenchus dipsaci on Alfalfa Mortality, Winterkill, and Yield.

Ditylenchus dipsaci-infected and noninfected alfalfa plants in a naturally infested field were studied from July 1980 to September 1982. Forty-one percent of the plants died during the study. Ninety-seven percent of the plants that died were infected with D. dipsaci. Sixty-nine percent of the observed mortality occurred during winter. Forage yield of infected plants was significantly lower than yield of noninfected plants at each harvest. Stored carbohydrates in infected plants were significantly lower than in noninfected plants. In a controlled environment test, significantly greater mortality occurred in frozen severely infected plants than in frozen noninfected plants, while no mortality occurred in severely infected or noninfected plants that were not frozen. Both forage yield and stored carbohydrates were significantly lower in severely infected than noninfected, non-frozen plants. Mortality in greenhouse-grown plants that were transplanted to field plots was significantly greater in D. dipsaci-infected plants than in noninfected plants after one winter.