scholarly journals Influence of Environment on Atmospheric Concentrations of Peronospora antirrhini Sporangia in Field-Grown Snapdragon

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1060-1066 ◽  
Author(s):  
J. M. Byrne ◽  
M. K. Hausbeck ◽  
L. E. Sconyers
Keyword(s):  
Average Length ◽  
Pathogen Resistance ◽  
Management Program ◽  
Leaf Wetness ◽  
Environmental Cues ◽  
Total Rainfall ◽  
Growing Seasons ◽  
Positive Correlations ◽  
Total Spore Count ◽  
Atmospheric Concentrations

Hourly concentrations of airborne sporangia of Peronospora antirrhini at a commercial snapdragon farm were investigated over three growing seasons to determine the influence of the environment on their occurrence and concentration. Hourly concentrations of sporangia of P. antirrhini were estimated using a Burkard volumetric spore sampler. Atmospheric sporangial concentrations followed a diurnal pattern and were greatest during 0500 to 1200 h. Minimum daily temperatures <10.0°C appeared to have a moderate limiting effect on atmospheric sporangial concentrations, whereas temperatures <6.0°C had more severe limiting effects. Maximum daily temperatures ≥30.0°C limited concentrations of atmospheric sporangia. Long dew periods (≥6 h) were associated with relatively large sporangia releases. On 69 days (1999 to 2001), the total number of sporangia trapped was >100/m3/day, and the average length of leaf wetness duration prior to these releases was 11 h. Consecutive days with short leaf wetness periods were associated with low atmospheric sporangial concentrations. Significant positive correlations (P = 0.0502 and P = 0.0174) were found between total rainfall and total spore count for both research plots in 2000. Information gained from this study will contribute to the development of a disease management program that utilizes environmental cues to prompt fungicide applications, thus increasing the efficiency of fungicide programs and delaying the development of pathogen resistance.

Ecology and productivity of Cantharellus cibarius var. roseocanus in two eastern Canadian jack pine stands

Botany ◽  
2011 ◽  
Vol 89 (10) ◽  
pp. 663-675 ◽  
Author(s):  
Caroline Rochon ◽  
David Paré ◽  
Nellia Pélardy ◽  
Damase P. Khasa ◽  
J. André Fortin
Keyword(s):  
Pinus Banksiana ◽  
C:N Ratio ◽  
Mineral Soil ◽  
Stand Density ◽  
Economic Importance ◽  
Site Conditions ◽  
Plant Association ◽  
Total Rainfall ◽  
Growing Seasons ◽  
Positive Correlations

Despite the economic importance of chanterelles, much remains to be known about their habitat requirements. Cantharellus cibarius var. roseocanus Redhead, Norvell & Danell sporocarp productivity was measured during three growing seasons in two Pinus banksiana Lamb. stands of boreal forest. The objective was to determine how the variability in stand, plant association, edaphic, and meteorological conditions was related to sporocarp productivity. DNA of this species was detected in organic and mineral soil horizons. Sporocarp productivity was similar for both stands, but the absence of colonies on trails at one of the sites likely reflects microenvironmental conditions that are unsuitable for chanterelle growth. Under the prevailing site conditions, preferred microhabitats were characterized by high stand density, high C:N ratio, and frequent moss presence. The Solidago puberula Nutt. – Comptonia peregrina (L.) Coulter – Pinus banksiana association, lichen presence, and as much clay and silt content as can possibly be found on this moderately acidic sandy soil favoured the productivity of this chanterelle, whereas ericaceous species presence was negatively correlated with chanterelle productivity. Positive correlations were found between total rainfall 1 week prior to fructification, air temperature 2 weeks prior to fructification, and sporocarp productivity. Results highlight the specific conditions favourable to Cantharellus cibarius var. roseocanus fructifications within these stands.

Reserve Bank of New Zealand

2005 ◽  
pp. 211-234 ◽  
Author(s):  
Yogesh Anand ◽  
David J. Pauleen ◽  
Sally Dexter
Keyword(s):  
Knowledge Management ◽  
New Zealand ◽  
Average Length ◽  
Management Strategies ◽  
Management Program ◽  
Document Management ◽  
Staff Members ◽  
Adoption And Implementation ◽  
Reserve Bank ◽  
Two Factors

This chapter outlines the adoption and implementation of knowledge management within the New Zealand Reserve Bank. In 1999, the Bank recognised that it had a very high exposure to loss of knowledge on departure of key staff. This was mainly due to two factors: recruitment of staff from a limited global pool of specifically skilled labour, and an average length of service of more than nine years during which time staff members accumulated an extensive knowledge of the Bank and its operations. In response to this and other challenges, the Bank embarked on an ongoing knowledge management program. The Bank invested significant resources into the program and from an initial corporate vision developed a knowledge management framework that led to the identification of potential areas of improvement within the organisation. The resulting knowledge strategy encompassed several key initiatives, the most significant of which was the goal of changing the organisational culture. Other initiatives included the consolidation of the Bank’s contact management into a single system, a review of the existing document management system, and information mapping. To date, while some initiatives have been achieved, others remain to be done. The challenge for the Bank now is to move from structured to unstructured processes for knowledge management and maintain the knowledge management focus while balancing available resources. The Bank must also consider how best to progress initiatives without necessarily attaching a specific knowledge management label, and identify ways to move ongoing development of knowledge management strategies to the next level.

scholarly journals Managing Onion Thrips can Limit Bacterial Stalk and Leaf Necrosis in Michigan Onion Fields

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 938-943 ◽  
Author(s):  
A. S. Grode ◽  
E. Brisco-McCann ◽  
P. Wiriyajitsonboom ◽  
M. K. Hausbeck ◽  
Z. Szendrei
Keyword(s):  
Cultural Practices ◽  
Disease Incidence ◽  
Insect Pest ◽  
Management Program ◽  
Thrips Tabaci ◽  
Onion Thrips ◽  
Leaf Necrosis ◽  
Positive Correlations ◽  
Thrips Population ◽  
Reduce Disease Severity

Onion thrips (Thrips tabaci) is a major insect pest of onion and it has been identified as a likely vector of Pantoea agglomerans (bacterial stalk and leaf necrosis), a relatively new pathogen to Michigan’s onion industry. Our objective was to develop an integrated insect and disease management program by examining the efficacy of bactericides and insecticides alone and in combination to limit bacterial stalk and leaf necrosis caused by P. agglomerans. We also examined the association of onion thrips and disease incidence in the field, because thrips are known to transmit this pathogen. In the pesticide trial, insecticides reduced both thrips abundance and bacterial stalk and leaf necrosis incidence whereas bactericides alone did not reduce disease severity. Positive correlations among thrips population density, numbers of thrips positive for P. agglomerans, and bacterial stalk and leaf necrosis incidence in onion fields were determined. This study suggests that onion thrips feeding can facilitate the development of bacterial stalk and leaf necrosis in Michigan’s commercial onion fields, and results from the pesticide trials indicate that thrips feeding damage is positively correlated with disease incidence. Therefore, in order to reduce bacterial stalk and leaf necrosis incidence in onion, management efforts should include reducing onion thrips populations through the use of insecticides and other cultural practices.

scholarly journals Effect of temperature, leaf wetness, and rainfall on the production of Guignardia citricarpa ascospores and on back spot severity on sweet orange

2006 ◽  
Vol 31 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Renato F. Reis ◽  
Lavern W. Timmer ◽  
Antonio de Goes
Keyword(s):  
Sweet Orange ◽  
Climatic Factors ◽  
Black Spot ◽  
Strong Relationship ◽  
Effect Of Temperature ◽  
Leaf Wetness ◽  
Total Rainfall ◽  
Spore Trap ◽  
Guignardia Citricarpa ◽  
Ascospore Production

The black spot of citrus (Citrus sp.) is caused by Guignardia citricarpa with ascospore production depending on temperature, leaf wetness, and rainfall. The number of ascospores produced was monitored using a spore trap and climatic factors were recorded using an automated meteorological station of 'Natal' and 'Valencia' sweet orange (Citrus sinensis) orchards in Mogi Guaçu in the state of São Paulo, Brazil, from November 2000 to March 2001. The fruits were bagged to prevent infection and the bags removed from different sets of fruit for one week during each of the 18 weeks of the season in both orchards. Ascospores were produced during the entire experimental period, from spring through summer, primarily after rain events. In both orchards, ascospore production reached a peak in January and February. Ascospore production was related to leaf wetness only in the Natal orange orchard but was not related to total rainfall or temperature in either orchard. Disease was most severe on fruit exposed the 7th, 8th, and 13th weeks after beginning the experiment in both cultivars as well as after the 16th week for 'Natal'. There was a strong relationship between disease severity and total rainfall for both orchards and a weak correlation between temperature and severity in the 'Natal' block only. There was no relationship between severity and leaf wetness or ascospore numbers.

Effects of Lake Size on Phytoplankton Photosynthesis

1992 ◽  
Vol 49 (12) ◽  
pp. 2445-2459 ◽  
Author(s):  
E. J. Fee ◽  
J. A. Shearer ◽  
E. R. DeBruyn ◽  
E. U. Schindler
Keyword(s):  
Interannual Variation ◽  
Additional Data ◽  
Climatic Warming ◽  
Lake Surface ◽  
Total Rainfall ◽  
Large Lakes ◽  
Growing Seasons ◽  
Shield Lakes ◽  
Lake Size ◽  
Phytoplankton Photosynthesis

Phytoplankton photosynthesis (PP) was measured for 6 yr in seven remote Canadian Shield lakes that stratify fully during the summer and have water renewal times > 5 yr but vary from 29 to 34 700 ha; Lakes Nipigon and Superior were also studied in two years. Chlorophyll and PP at optimum light were low in the smallest and largest lakes and increased systematically to values nearly five times higher in midsized lakes (~103 ha). Daily PP per square metre of lake surface and annual PP per cubic metre of the mixed layer also varied in this manner, but annual PP per square metre was high in large lakes (despite their low density rates) because of their long growing seasons. Additional data are needed to determine whether the photosynthesis maximum in midsized lakes is inherently size related or an accidental statistical result. Intraannually, chlorophyll-based photosynthesis parameters ([Formula: see text], αB) were similar in all lake sizes, but interannually they varied by two to three times; this interannual variation was significantly correlated with total rainfall during May and June. Implications for extrapolating experimental results from small to large lakes, selecting lakes for interregional comparison studies and predicting how climatic warming would affect phytoplankton photosynthesis are discussed.

scholarly journals Application and validation of a warning system for grapevine downy mildew controlusing fungicides

2013 ◽  
Vol 39 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Erlei Melo Reis ◽  
Olavo Roberto Sônego ◽  
Cristiano de Sales Mendes
Keyword(s):  
Downy Mildew ◽  
Warning System ◽  
Leaf Wetness ◽  
Warning Systems ◽  
Conventional System ◽  
Grapevine Downy Mildew ◽  
Growing Seasons ◽  
Plant Disease Control ◽  
Target Disease ◽  
Electronic Sensors

Most warning systems for plant disease control are based on Vinho, in Bento Gonçalves - RS, during the growing seasons 2000/ weather models dependent on the relationships between leaf wetness 01, 2002/03 and 2003/2004, using the grape cultivar Isabel. The duration and mean air temperature in this period considering the conventional system used by local growers was compared with the target disease intensity. For the development of a warning system to new warning system by using different cumulative daily disease severity control grapevine downy mildew, the equation generated by Lalancette values (CDDSV) as the criterion to schedule fungicide application and et al. (7) was used. This equation was employed to elaborate a critical reapplication. In experiments conducted in 2003/04, CDDSV of 12 - period table and program a computerized device, which records, though 14 showed promising to schedule the first spraying and the interval electronic sensors, leaf wetness duration, mean temperature in this between fungicide applications, reducing by 37.5% the number of period and automatically calculates the daily value of probability of applications and maintaining the same control efficiency in leaves infection occurrence. The system was validated at Embrapa Uva e and bunches, similarly to the conventional system.

scholarly journals Temporal and Spatial Distribution of Tomato Bacterial Wilt on Virginia's Eastern Shore

2011 ◽  
Vol 21 (2) ◽  
pp. 198-201 ◽  
Author(s):  
Adam F. Wimer ◽  
Steven L. Rideout ◽  
Joshua H. Freeman
Keyword(s):  
Spatial Distribution ◽  
Bacterial Wilt ◽  
Disease Incidence ◽  
Individual Plant ◽  
Eastern Shore ◽  
Temporal And Spatial Distribution ◽  
Intimate Contact ◽  
Growing Seasons ◽  
Temporal And Spatial ◽  
Positive Correlations

Bacterial wilt of tomato caused by Ralstonia solanacearum is one of the most devastating diseases of tomato (Solanum lycopersicum) on the Eastern Shore of Virginia (ESV). Four research trials were conducted on the ESV over three growing seasons to determine the temporal and spatial distribution of bacterial wilt throughout commercial tomato fields. Individual plants were assessed at ≈1-week intervals throughout the growing seasons with the incidence of bacterial wilt for each individual plant being recorded. Bacterial wilt increased gradually during each growing season. An increase in the clustered distribution of symptomatic plants was determined to exist within rows but not across rows. There were positive correlations between disease incidence and the percentage of rows exhibiting a significantly clustered distribution in every trial. These findings suggest that as bacterial wilt incidence increases in tomato fields by either the intimate contact between roots of adjacent tomato plants or the movement of the pathogen in surface irrigation water, symptomatic plants become more clustered within rows.

scholarly journals Flowering Phenology of Selected Linden (Tilia L.) Taxa in Relation to Pollen Seasons

2016 ◽  
Vol 60 (2) ◽  
pp. 193-208
Author(s):  
Agnieszka Dąbrowska ◽  
Krystyna Piotrowska-Weryszko ◽  
Elżbieta Weryszko-Chmielewska ◽  
Ryszard Sawicki
Keyword(s):  
Pollen Season ◽  
Airborne Pollen ◽  
Average Length ◽  
Pollen Grains ◽  
Flowering Phenology ◽  
Flowering Period ◽  
Growing Seasons ◽  
Time Period ◽  
Relative Air Humidity ◽  
Atmospheric Pollen

Abstract All lindens provide Apidae insects with nectar, pollen, and honeydew. Lindens are important melliferous trees in Poland. The first purpose of the study was to carry out phenological observations of the flowering in ten linden taxa. The second aim was to analyse the content of linden pollen grains in the air of Lublin. A correlation between the parameters of the pollen season and meteorological factors was also determined. This study was conducted in the city of Lublin located in the central-eastern part of Poland. The flowering phenophases were analysed, using the method developed by Łukasiewicz, during the growing seasons of 2012-2015. Aerobiological monitoring, which was based on the volumetric method, was carried out over the 2001-2014 time period. As shown in the study, the flowering period of all the analysed linden taxa lasted 7 weeks, on average, from June 7 to July 24. The average length of the flowering period of the investigated taxa and hybrids was in the range of 12-17 days. Their flowering periods overlapped. The atmospheric pollen season lasted, on average, from mid-June to the second 10-day period of July. The highest concentration of airborne pollen was noted at the end of June. The pollen season pattern was significantly affected by temperature and relative air humidity as well as by rainfall in May and June. The investigations indicate a 9-day acceleration of the pollen season, which may be associated with global warming.

scholarly journals Spatial Heterogeneity of Leaf Wetness Duration in Apple Trees and Its Influence on Performance of a Warning System for Sooty Blotch and Flyspeck

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 164-170 ◽  
Author(s):  
J. C. Batzer ◽  
M. L. Gleason ◽  
S. E. Taylor ◽  
K. J. Koehler ◽  
J. E. B. A. Monteiro
Keyword(s):  
Warning System ◽  
Sole Source ◽  
Operational Reliability ◽  
Leaf Wetness ◽  
Data Sets ◽  
Apple Trees ◽  
Leaf Wetness Duration ◽  
Growing Seasons ◽  
Sooty Blotch ◽  
Sooty Blotch And Flyspeck

To determine the effect of sensor placement on the performance of a disease-warning system for sooty blotch and flyspeck (SBFS), we measured leaf wetness duration (LWD) at 12 canopy positions in apple trees, then simulated operation of the disease-warning system using LWD measurements from different parts of the canopy. LWD sensors were placed in four trees within one Iowa orchard during two growing seasons, and in one tree in each of four orchards during a single growing season. The LWD measurements revealed substantial heterogeneity among sensor locations. In all data sets, the upper, eastern portion of the canopy had the longest mean daily LWD, and was the first site to form dew and the last to dry. The lower, western portion of the canopy averaged about 3 h less LWD per day than the top of the canopy, and was the last zone where dew formed and the first to dry off. On about 25% of nights when dew occurred in the top of the canopy, no dew formed in the lower, western canopy. Intracanopy variability of LWD was more pronounced when dew was the sole source of wetness than on days when rainfall occurred. Daily LWD in the upper, eastern portion of the canopy was slightly less than reference measurements made at a 0.7-m height over turfgrass located near the orchard. When LWD measurements from several canopy positions were input to the SBFS warning system, timing of occurrence of a fungicide-spray threshold varied by as much as 30 days among canopy positions. Under Iowa conditions, placement of an LWD sensor at an unobstructed site over turfgrass was a fairly accurate surrogate for the wettest part of the canopy. Therefore, such an extra-canopy LWD sensor might be substituted for a within-canopy sensor to enhance operational reliability of the SBFS warning system.

Using infrared thermography to assess viability of Pinussylvestris and Piceaabies seedlings before planting

1993 ◽  
Vol 23 (9) ◽  
pp. 1737-1743 ◽  
Author(s):  
Gustaf Egnell ◽  
Göran Örlander
Keyword(s):  
Infrared Thermography ◽  
Storage Temperature ◽  
Ambient Air ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Lower Survival Rate ◽  
Growing Seasons ◽  
Positive Correlations ◽  
One Year

One-year-old Scots pine (Pinussylvestris L.) and 2-year-old Norway spruce (Piceaabies (L.) Karst.) seedlings were lifted and stored under an array of conditions to test infrared thermography as a means of determining seedling viability. After winter storage, temperature was measured on each seedling with an infrared thermovision scanner (3–5 μm) in an environment favoring transpiration (vapor pressure deficit of the ambient air 1.6–2.9 kPa, photosynthetic photon flux density 1500 μmol•m−2•s−1). Thereafter the seedlings were planted in the field. Visual signs of damage were assessed and annual height increments were measured after one and two growing seasons. Significant positive correlations were found between seedling temperature and degree of damage. The warmest seedlings had a lower survival rate as a group when compared with the remaining seedlings. There were significant negative correlations between seedling temperature and annual height increment in the first growing season.

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