scholarly journals Fusarium root and crown rot in alfalfa subjected to autumn harvests

2002 ◽  
Vol 82 (3) ◽  
pp. 621-624 ◽  
Author(s):  
L. Couture ◽  
C. Dhont ◽  
F.-P. Chalifour ◽  
R. Drapeau ◽  
G. Tremblay ◽  
...  
Keyword(s):  
Key Words ◽  
Disease Severity ◽  
Crown Rot ◽  
Growing Degree Days ◽  
Harvest Management ◽  
Degree Days ◽  
Root And Crown Rot

Fusarium root and crown rot in alfalfa subjected to an autumn harvest was studied in plots established in the spring of 1996 or 1997, at three sites in Quebec. Autumn harvest treatments were started the year following establishment at each site. They were made at either 400, 500 or 600 growing degree-days (GDD; 5°C) after the last summer harvest. Samples were assessed for fusarium root and crown rot severity in autumn 1998 and spring 1999. Disease severity over all sites, cultivars, and sampling periods was ranked in the following order: 400 GDD > 500 GDD > 600 GDD > control (no fall harvest). Key words: Fusarium, root and crown rot, alfalfa, harvest management

Comparison of two air temperature based models for predicting phenophase occurrence in Persian lilacs (Syringa chinensis) cultivar Red Rothomagensis

1990 ◽  
Vol 68 (5) ◽  
pp. 1113-1116 ◽  
Author(s):  
Gary W. Moorman ◽  
James L. Rosenberger ◽  
Leslie A. Gladstone
Keyword(s):  
Mathematical Models ◽  
Key Words ◽  
Growth Model ◽  
Air Temperature ◽  
Growing Degree Days ◽  
Bud Break ◽  
Degree Days ◽  
Flower Bud ◽  
Phenological Data ◽  
Vegetative Bud

Phenological data collected for 9–11 years from genetically uniform Persian lilacs (Syringa chinensis L.) cultivar Red Rothomagensis were analyzed to determine whether the number of days elapsed between vegetative bud break and flower bud break is correlated with either the accumulated growing degree-days or the average daily temperature. The lack of statistically significant correlations between these variables suggests these mathematical models cannot accurately predict the onset of flower bud break for this cultivar. Key words: degree-days, growth model, phenology.

scholarly journals A combined BSA-Seq and linkage mapping approach identifies genomic regions associated with Phytophthora root and crown rot resistance in squash

2020 ◽  
Author(s):  
Gregory Vogel ◽  
Kyle E. LaPlant ◽  
Michael Mazourek ◽  
Michael A. Gore ◽  
Christine D. Smart
Keyword(s):  
Disease Severity ◽  
Linkage Mapping ◽  
Prediction Models ◽  
Bulked Segregant Analysis ◽  
Phytophthora Capsici ◽  
Multiple Linear Regression Model ◽  
Crown Rot ◽  
Phenotypic Variance ◽  
Root And Crown Rot ◽  
Genomic Regions

AbstractPhytophthora root and crown rot, caused by the soilborne oomycete pathogen Phytophthora capsici, leads to severe yield losses in squash (Cucurbita pepo). To identify quantitative trait loci (QTL) involved in resistance to this disease, we crossed a partially resistant squash breeding line with a susceptible zucchini cultivar and evaluated over 13,000 F2 seedlings in a greenhouse screen. Bulked segregant analysis with whole genome resequencing (BSA-Seq) resulted in the identification of five genomic regions – on chromosomes 4, 5, 8, 12, and 16 – featuring significant allele frequency differentiation between susceptible and resistant bulks in each of two independent replicates. In addition, we conducted linkage mapping using a population of 176 F3 families derived from individually genotyped F2 individuals. Variation in disease severity among these families was best explained by a four-QTL model, comprising the same loci identified via BSA-Seq on chromosomes 4, 5, and 8 as well as an additional locus on chromosome 19, for a combined total of six QTL identified between both methods. Loci, whether those identified by BSA-Seq or linkage mapping, were of small to moderate effect, collectively accounting for 28-35% and individually for 2-10% of the phenotypic variance explained. However, a multiple linear regression model using one marker in each BSA-Seq QTL could predict F2:3 disease severity with only a slight drop in cross-validation accuracy compared to genomic prediction models using genome-wide markers. These results suggest that marker-assisted selection could be a suitable approach for improving Phytophthora crown and root rot resistance in squash.

Comparison of meadow fescue and meadow bromegrass in monoculture and in association with white clover

2009 ◽  
Vol 89 (6) ◽  
pp. 1059-1063 ◽  
Author(s):  
R Drapeau ◽  
G Bélanger
Keyword(s):  
Key Words ◽  
White Clover ◽  
Trifolium Repens ◽  
Grass Species ◽  
Growing Degree Days ◽  
Festuca Pratensis ◽  
Degree Days ◽  
Meadow Fescue ◽  
Bromus Riparius ◽  
Meadow Bromegrass

Meadow fescue and meadow bromegrass alone or with white clover were compared in a four cut system in a region with less than 1400 growing degree days. Cultivars of the two grass species did not affect yield. The annual yields of two grass species, alone or with white clover, were similar in the first production year, but in second and third production years, meadow bromegrass yielded more than meadow fescue. The persistence of white clover, alone or with a grass, was limited. Key words: Festuca pratensis, Bromus riparius, Trifolium repens, yield

Evaluation of Finger Millet Varieties under Rainfed Condition of Eastern India

2017 ◽  
Vol 4 (03) ◽  
Author(s):  
M. K. Singh ◽  
VINOD KUMAR ◽  
SHAMBHU PRASAD
Keyword(s):  
Field Experiment ◽  
Finger Millet ◽  
Yield Potential ◽  
Growing Degree Days ◽  
Eastern India ◽  
Degree Days ◽  
Rainfed Condition ◽  
Net Returns ◽  
Humid Environment ◽  
Use Efficiency

A field experiment was carried out during the kharif of 2014 and 2015 to evaluate the yield potential, economics and thermal utilization in eleven finger millet varieties under the rainfed condition of the sub-humid environment of South Bihar of Eastern India. Results revealed that the significantly higher grain yield (20.41 q ha-1), net returns (Rs 25301) and B: C ratio (1.51) was with the finger millet variety ‘GPU 67’ but was being at par to ‘GPU28’and ‘RAU-8’, and significantly superior over remaining varieties. The highest heat units (1535.1oC day), helio-thermal units (7519.7oC day hours), phenothermal index (19.4 oC days day-1) were recorded with variety ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ and lowest in ‘VL 149’ at 50 % anthesis stage. Similarly, the highest growing degree days (2100 oC day), helio-thermal units (11035.8 oC day hours) were noted with ‘GPU 67’ followed by ‘RAU 8’ and ‘GPU 28’ at maturity. The highest heat use efficiency (0.97 kg ha-1 oC day) and helio-thermal use efficiency (0.19 kg ha-1 oC day hour) were in ‘GPU 67’ followed by ‘VL 315’.

scholarly journals Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

2019 ◽  
Vol 33 (6) ◽  
pp. 800-807 ◽  
Author(s):  
Graham W. Charles ◽  
Brian M. Sindel ◽  
Annette L. Cowie ◽  
Oliver G. G. Knox
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Yield Loss ◽  
Field Studies ◽  
Growing Degree Days ◽  
Degree Days ◽  
Weed Density ◽  
High Level ◽  
The Cost ◽  
Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

Root and crown rot of strawberry caused by Pythium helicoides and its distribution in strawberry production areas of Japan

2014 ◽  
Vol 80 (5) ◽  
pp. 423-429 ◽  
Author(s):  
Yasushi Ishiguro ◽  
Kayoko Otsubo ◽  
Hideki Watanabe ◽  
Mikihiko Suzuki ◽  
Kiichi Nakayama ◽  
...  
Keyword(s):  
Crown Rot ◽  
Root And Crown Rot ◽  
Pythium Helicoides ◽  
Production Areas

scholarly journals Growth and Development of Purple Nutsedge Based on Days or Thermal Units

2015 ◽  
Vol 33 (2) ◽  
pp. 165-173 ◽  
Author(s):  
R.S.O. Lima ◽  
E.C.R. Machado ◽  
A.P.P. Silva ◽  
B.S. Marques ◽  
M.F. Gonçalves ◽  
...  
Keyword(s):  
Plant Growth ◽  
Mathematical Models ◽  
Growth And Development ◽  
Dry Matter ◽  
Cyperus Rotundus ◽  
Growing Degree Days ◽  
Plant Growth And Development ◽  
Degree Days ◽  
Purple Nutsedge ◽  
Independent Trials

This work was carried out with the objective of elaborating mathematical models to predict growth and development of purple nutsedge (Cyperus rotundus) based on days or accumulated thermal units (growing degree days). Thus, two independent trials were developed, the first with a decreasing photoperiod (March to July) and the second with an increasing photoperiod (August to November). In each trial, ten assessments of plant growth and development were performed, quantifying total dry matter and the species phenology. After that, phenology was fit to first degree equations, considering individual trials or their grouping. In the same way, the total dry matter was fit to logistic-type models. In all regressions four temporal scales possibilities were assessed for the x axis: accumulated days or growing degree days (GDD) with base temperatures (Tb) of 10, 12 and 15 oC. For both photoperiod conditions, growth and development of purple nutsedge were adequately fit to prediction mathematical models based on accumulated thermal units, highlighting Tb = 12 oC. Considering GDD calculated with Tb = 12 oC, purple nutsedge phenology may be predicted by y = 0.113x, while species growth may be predicted by y = 37.678/(1+(x/509.353)-7.047).

scholarly journals PhytophthoraSpecies Are Common on Nursery Stock Grown for Restoration and Revegetation Purposes in California

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 448-455 ◽  
Author(s):  
S. Rooney-Latham ◽  
C. L. Blomquist ◽  
K. L. Kosta ◽  
Y. Y. Gou ◽  
P. W. Woods
Keyword(s):  
North America ◽  
Phytophthora Species ◽  
Molecular Techniques ◽  
Crown Rot ◽  
Native Plant ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Root And Crown Rot ◽  
Symptomatic Tissue ◽  
First Time

Phytophthora tentaculata was detected for the first time in North America in 2012 in a nursery on sticky monkeyflower plant (Diplacus aurantiacus) and again in 2014 on outplanted native plants. At that time, this species was listed as a federally actionable and reportable pathogen by the USDA. As a result of these detections, California native plant nurseries were surveyed to determine the prevalence of Phytophthora species on native plant nursery stock. A total of 402 samples were collected from 26 different native plant nurseries in California between 2014 and 2016. Sampling focused on plants with symptoms of root and crown rot. Symptomatic tissue was collected and tested by immunoassay, culture, and molecular techniques (PCR). Identifications were made using sequences from the internal transcribed spacer (ITS) rDNA region, a portion of the trnM-trnP-trnM, or the atp9-nad9 mitochondrial regions. Phytophthora was confirmed from 149 of the 402 samples (37%), and from plants in 22 different host families. P. tentaculata was the most frequently detected species in our survey, followed by P. cactorum and members of the P. cryptogea complex. Other species include P. cambivora, P. cinnamomi, P. citricola, P. hedraiandra, P. megasperma, P. multivora, P. nicotianae, P. niederhauserii, P. parvispora, P. pini, P. plurivora, and P. riparia. A few Phytophthora sequences generated from mitochondrial regions could not be assigned to a species. Although this survey was limited to a relatively small number of California native plant nurseries, Phytophthora species were detected from three quarters of them (77%). In addition to sticky monkeyflower, P. tentaculata was detected from seven other hosts, expanding the number of associated hosts. During this survey, P. parvispora was detected for the first time in North America from symptomatic crowns and roots of the nonnative Mexican orange blossom (Choisya ternata). Pathogenicity of P. parvispora and P. nicotianae was confirmed on this host. These findings document the widespread occurrence of Phytophthora spp. in native plant nurseries and highlight the potential risks associated with outplanting infested nursery-grown stock into residential gardens and wildlands.

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