scholarly journals Different pathogenicity of ergot isolates (Claviceps purpurea [Fr.] Tul.) on Kentucky bluegrass (Poa pratensis L.)

2012 ◽  
Vol 38 (No. 1) ◽  
pp. 18-22 ◽  
Author(s):  
B. Cagaš ◽  
R. Macháč
Keyword(s):  
Poa Pratensis ◽  
Weather Conditions ◽  
Kentucky Bluegrass ◽  
Storage Conditions ◽  
Washington State ◽  
Claviceps Purpurea ◽  
Central European ◽  
Growing Period ◽  
Role Based ◽  
Harvest Year

Ergot, caused by the fungus Claviceps purpurea (Fr.) Tul., belongs to the main constraints in seed production of Kentucky bluegrass (Poa pratensis L.). The level of ergot occurrence depends on the weather conditions during the growing period, harvest year, storage conditions of seed, and post-harvest treatment. The degree of resistance of the grown cultivar plays an important role. Based on greenhouse trials with four different ergot populations (Zubří, Czech Republic; Leutewitz and Munich, Germany; Pullman, Washington, USA) during 3 years, we found pathogenicity to be one of the most important factors. There were significant differences in the amount of ergot bodies formed between the Central European populations (Zubří, Leutewitz) and the American one from Washington State. The degree of pathogenicity has a major impact on the occurrence of ergot sclerotia in seed of Poa pratensis. 

scholarly journals Optimising Clearfield and ExpressSun sunflower technologies for Central European conditions

2017 ◽  
Vol 53 (No. 4) ◽  
pp. 265-272 ◽  
Author(s):  
Jursík Miroslav ◽  
Fendrychová Veronika ◽  
Kolářová Michaela ◽  
Andr Jiří ◽  
Soukup Josef
Keyword(s):  
Chenopodium Album ◽  
Weather Conditions ◽  
Field Trials ◽  
Growth Stages ◽  
Split Application ◽  
Central European ◽  
Growing Period ◽  
Dry Conditions

The efficacy and selectivity of herbicides and tank-mix combinations at different application terms in Clearfield and ExpressSun sunflowers were evaluated. Five-plot field trials (2011–2015) were carried out in Prague. The efficacy of tribenuron (TBM) was excellent and quite rapid on Chenopodium album. Its efficacy on other tested dicot weeds ranged around 90%, depending on weather conditions and growth stages of weeds. Echinochloa crus-galli was not controlled by TBM. The tank-mix combination of TBM + propaquizafop (PQF) caused sunflower injury when applied in a very cold growing period. Under dry conditions, PQF efficacy on E. crus-galli was strongly reduced. The split application of TBM, when PQF was used at the second application, was less negatively affected by herbicide antagonisms. Very good results were obtained on plots with pre-emergence treatment with dimethenamid and post-emergence with TBM. The efficacy of imazamox (IZM) on dicot weeds was strongly affected by growth stages of weed and weather conditions during application. Efficacy of IZM on E. crus-galli was increased by oil adjuvant, but this adjuvant reduced IZM selectivity. The best efficacy, selectivity, and Clearfield sunflower yield were on plots with the split application of IZM.

scholarly journals Afternoon Ascospore Release in Claviceps purpurea Optimizes Perennial Ryegrass Infection

Plant Disease ◽  
2015 ◽  
Vol 99 (10) ◽  
pp. 1410-1415 ◽  
Author(s):  
Stephen C. Alderman ◽  
Darrin L. Walenta ◽  
Philip B. Hamm ◽  
Ruth C. Martin ◽  
Jeremiah Dung ◽  
...  
Keyword(s):  
Perennial Ryegrass ◽  
Internal Transcribed Spacer ◽  
Poa Pratensis ◽  
Random Amplified Polymorphic Dna ◽  
Kentucky Bluegrass ◽  
Early Morning ◽  
Its Sequences ◽  
Claviceps Purpurea ◽  
Dna Evidence ◽  
Spore Release

In Kentucky bluegrass (Poa pratensis), Claviceps purpurea, the causal agent of ergot, typically releases ascospores during the early-morning hours, between about midnight and 10:00 a.m., corresponding to time of flowering, when the unfertilized ovaries are most susceptible to infection. During aeromycology studies of C. purpurea in perennial ryegrass (Lolium perenne) in northeastern Oregon during 2008 to 2010 and 2013, a strain of C. purpurea was found that released ascospores in the afternoon, coinciding with flowering in perennial ryegrass. Under controlled environmental conditions, sclerotia from perennial ryegrass and Kentucky bluegrass released spores in the afternoon and morning, respectively, consistent with timing of spore release under field conditions. Internal transcribed spacer (ITS) sequences of single sclerotial isolates from Kentucky bluegrass and perennial ryegrass were consistent with C. purpurea, although minor variations in ITS sequences among isolates were noted. Differences between Kentucky bluegrass and perennial ryegrass isolates were observed in random amplified polymorphic DNA. Evidence is provided for adaptation of C. purpurea to perennial ryegrass by means of delayed spore release that coincides with afternoon flowering in perennial ryegrass.

scholarly journals Outbreak of Ergot (Claviceps purpurea) in Iowa Barley, 1996

Plant Disease ◽  
1997 ◽  
Vol 81 (7) ◽  
pp. 830-830 ◽  
Author(s):  
G. P. Munkvold ◽  
T. Carson ◽  
D. Thoreson
Keyword(s):  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Phleum Pratense ◽  
Influential Factors ◽  
Claviceps Purpurea ◽  
State University ◽  
Forage Grasses ◽  
Science Center ◽  
Pasture Grasses ◽  
Contamination Levels

An outbreak of ergot, caused by Claviceps purpurea, occurred in barley (Hordeum vulgare) grown in northeastern Iowa and southwestern Wisconsin in 1996. In a nine-county area of intensive dairy production in Iowa, approximately 40% of the barley hectarage (approximately 1,200 ha) was affected by the disease. Several cultivars were affected, including Robust, Excel, and Chilton, and no differences in ergot contamination levels were observed among cultivars. Barley samples examined by the Iowa State University Seed Science Center averaged 0.2% ergot by weight, with a maximum of 0.53%. Prolonged cool, wet weather during heading and greater barley planting than usual contributed to the high incidence of infection, but other influential factors have not been identified. Symptoms were not noticed in barley in the field and much of the infested grain was fed to cattle (primarily dairy cows), resulting in a considerable incidence of ergotism. An estimated 1,000 animals displayed symptoms of ergotism, manifested as loss of milk production and hyperthermia. Approximately 10 to 15 animals died or were destroyed. Ergot also was prevalent in forage grasses, including brome (Bromus spp.), Kentucky bluegrass (Poa pratensis), orchardgrass (Dactylis glomerata), quackgrass (Agropyron repens), and timothy (Phleum pratense). Minor symptoms of ergotism were associated with consumption of infested hay and pasture grasses. Negligible incidences of ergot occur annually in small grains and forage grasses in Iowa; ergotism of this extent has not been observed for several decades. Crop rotation and early harvest of grass hay have been recommended for 1997 to prevent a recurrence of the disease.

Nitrogen fixation associated with 'Park' Kentucky bluegrass (Poapratensis L.)

1979 ◽  
Vol 25 (10) ◽  
pp. 1197-1200 ◽  
Author(s):  
R. C. Shearman ◽  
W. L. Pedersen ◽  
R. V. Klucas ◽  
E. J. Kinbacher
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Acetylene Reduction Activity ◽  
Controlled Environment ◽  
Nitrogen Accumulation ◽  
Reduction Activity ◽  
Significant Difference ◽  
Reduction Assay

Associative nitrogen fixation in Kentucky bluegrass (Poa pratensis L.) turfs inoculated with five nitrogen-fixing bacterial isolates was evaluated using the acetylene reduction assay and nitrogen accumulation as indicators of fixation. 'Park' and 'Nugget' Kentucky bluegrass turfs were grown in controlled environment chambers and inoculated with Klebsiella pneumoniae (W-2, W-6, and W-14), Erwinia herbicola (W-8), and Enterobacter cloacae (W-11). 'Park' inoculated with K. pneumoniae (W-6) had significant acetylene reduction activity using undisturbed turfs. Other treatments including turfs treated with heat-killed cells had no significant difference in acetylene reduction. In a second study, 'Park' and 'South Dakota Certified' turfs were grown in a greenhouse and inoculated with K. pneumoniae (W-6) and E. herbicola (W-8). 'Park' inoculated with K. pneumoniae (W-6) had increased acetylene reduction activity rates and also a greater nitrogen accumulation in aerial tissues when compared to controls. Acetylene reduction activity was correlated (r = 0.92) to nitrogen accumulation. Other treatments did not effectively increase acetylene reduction activity or nitrogen accumulation.

Nitrogen fixation (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Surface Sterilization ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.

SELECTIVE CONTROL OF ANNUAL BLUEGRASS IN KENTUCKY BLUEGRASS TURF WITH LINURON

1979 ◽  
Vol 59 (2) ◽  
pp. 469-473 ◽  
Author(s):  
R. G. INGRATTA ◽  
G. R. STEPHENSON ◽  
C. M. SWITZER
Keyword(s):  
Temperature Regime ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Controlled Environment ◽  
Night Temperature ◽  
Annual Bluegrass ◽  
Selective Control ◽  
Excellent Control

Optimum top growth of annual bluegrass (Pao annua L.) and Kentucky bluegrass (Poa pratensis L.) was obtained at 24/12 °C day/night temperature regime in controlled environment studies. The tolerance of seedling Kentucky bluegrass to linuron [3-(3,4-dichlorophenyl)-1)methylurea] appeared to be greatest at this temperature regime when photoperiods were 16 h in length. A granular formulation of linuron gave excellent control of annual bluegrass in Kentucky bluegrass turf at 6.7 kg/ha when applied postemergence. At this rate, all culitivars of Kentucky bluegrass tested, with the exception of Fylking, were tolerant to linuron as a granular formulation. After application of linuron at 3.4–6.7 kg/ha, phytotoxic residues remained in the soil at sufficient levels to injure seedling Kentucky bluegrass for up to 3 mo.

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