scholarly journals Relative Performance of Strawberry Cultivars and Native Hybrids on Fumigated and Nonfumigated Soil in Michigan

HortScience ◽  
2001 ◽  
Vol 36 (1) ◽  
pp. 136-138 ◽  
Author(s):  
James F. Hancock ◽  
Peter W. Callow ◽  
Sedat Serçe ◽  
Annemiek C. Schilder
Keyword(s):  
Methyl Bromide ◽  
Root Rot ◽  
Fine Roots ◽  
Relative Performance ◽  
The Other ◽  
Meloidogyne Hapla ◽  
Root Knot Nematode ◽  
Black Root Rot ◽  
Strawberry Cultivars ◽  
Better Than

The performance of four California and 11 eastern cultivars of Fragaria×ananassa Duchesne in Lamarck, and 12 elite F1 hybrids of Fragaria×ananassa with F. virginiana Miller in their immediate background was evaluated in a producer's field with and without methyl bromide-chloropicrin fumigation. Averaged across all genotypes, plants in nonfumigated soils had 43% fewer runners, 18% smaller fruit, and 46% lower yields than did plants on fumigated soil. They also had an average of 27% fewer crowns, 49% more root discoloration, significantly fewer fine roots, and showed symptoms of the black root rot syndrome. The most commonly isolated pathogens from discolored roots were Pythium sp., Rhizoctonia sp., Idriella lunata P.E. Nelson & K. Wilh., and the root-knot nematode (Meloidogyne hapla Chitwood). The performance of all genotypes was enhanced by fumigation, although the F. virginiana hybrids performed comparatively better than the other cultivars on nonfumigated soils.

Interaction of Meloidogyne hapla and Verticillium dahliae, and the chemical control of wilt in strawberry

1970 ◽  
Vol 10 (45) ◽  
pp. 493 ◽  
Author(s):  
JW Meagher ◽  
PT Jenkins
Keyword(s):  
Broad Spectrum ◽  
Verticillium Dahliae ◽  
Methyl Bromide ◽  
Chemical Control ◽  
Soil Fumigation ◽  
Meloidogyne Hapla ◽  
Root Knot Nematode ◽  
Methyl Isothiocyanate ◽  
Severity Of Disease ◽  
Verticillium Dahliae Kleb

In a field experiment with strawberries, pre-plant treatments with broad-spectrum fumigants methyl bromide-chloropicrin (450 kg/ha) or methyl isothiocyanate-dichloropropene (500 l/ha) (and 300 l/ha) controlled wilt caused by Verticillium dahliae Kleb and resulted in increased yields. Soil fumigation with the nematicide ethylene dibromidz (105 l/ha) also improved yields. It controlled the root-knot nematode (Meloidogyne hapla Chitwood), delayed the onset of wilt symptoms and reduced the severity of disease. This indicated a nematode-fungus interaction and is the first report of a Meloidogyne-Verticillium interaction in strawberry.

scholarly journals Enhancing direct citations: A comparison of relatedness measures for community detection in a large set of PubMed publications

2020 ◽  
pp. 1-16 ◽  
Author(s):  
Per Ahlgren ◽  
Yunwei Chen ◽  
Cristian Colliander ◽  
Nees Jan van Eck
Keyword(s):  
Community Detection ◽  
Relative Performance ◽  
The Other ◽  
Evaluation Criterion ◽  
Bibliographic Coupling ◽  
Large Set ◽  
Classification Schemes ◽  
Coupling Approach ◽  
Solution Accuracy ◽  
Better Than

The effects of enhancing direct citations, with respect to publication–publication relatedness measurement, by indirect citation relations (bibliographic coupling, cocitation, and extended direct citations) and text relations on clustering solution accuracy are analyzed. For comparison, we include each approach that is involved in the enhancement of direct citations. In total, we investigate the relative performance of seven approaches. To evaluate the approaches we use a methodology proposed by earlier research. However, the evaluation criterion used is based on MeSH, one of the most sophisticated publication-level classification schemes available. We also introduce an approach, based on interpolated accuracy values, by which overall relative clustering solution accuracy can be studied. The results show that the cocitation approach has the worst performance, and that the direct citations approach is outperformed by the other five investigated approaches. The extended direct citations approach has the best performance, followed by an approach in which direct citations are enhanced by the BM25 textual relatedness measure. An approach that combines direct citations with bibliographic coupling and cocitation performs slightly better than the bibliographic coupling approach, which in turn has a better performance than the BM25 approach.

scholarly journals Application of Preplant Fumigants via Drip Irrigation Systems for the Management of Root Rot of Melons Caused by Monosporascus cannonballus

Plant Disease ◽  
2003 ◽  
Vol 87 (10) ◽  
pp. 1176-1178 ◽  
Author(s):  
M. E. Stanghellini ◽  
D. M. Ferrin ◽  
D. H. Kim ◽  
M. M. Waugh ◽  
K. C. Radewald ◽  
...  
Keyword(s):  
Methyl Bromide ◽  
Drip Irrigation ◽  
Root Rot ◽  
Irrigation Systems ◽  
Monosporascus Cannonballus ◽  
Hot Gas ◽  
Equivalent Rate ◽  
Vine Decline ◽  
Pathogen Populations ◽  
Better Than

Root rot and vine decline, caused by Monosporascus cannonballus, is a destructive disease of melons in the desert production regions of southern California. In 1998, we initiated studies on the use of preplant fumigation to reduce resident pathogen populations in soil. Preplant fumigation with methyl iodide injected as a hot gas at 448.4 kg/ha through drip irrigation tape in preformed, tarped beds consistently provided significant (P < 0.05) reductions in the percentage of roots infected compared with the nonfumigated controls; these reductions were equal to or better than those achieved with an equivalent rate (448.4 kg/ha) of methyl bromide. Chloropicrin applied in water at 249.0 kg/ha through buried drip irrigation tape to either tarped or nontarped beds significantly (P < 0.05) reduced the percentages of both roots infected and roots on which perithecia were produced compared with nonfumigated controls.

Microfungi of crowns and roots of apparently healthy dormant strawberry plants

1969 ◽  
Vol 47 (6) ◽  
pp. 945-949 ◽  
Author(s):  
C. O. Gourley
Keyword(s):  
Root Rot ◽  
The Other ◽  
Fusarium Spp ◽  
Fungal Flora ◽  
Black Root Rot ◽  
Fruit Pathogens ◽  
Apparently Healthy

The crowns and roots of 100 cold-stored, apparently healthy strawberry plants of each of the varieties Acadia, Catskill, Cavalier, Gorella, Guardsman, Midway, Redcoat, Sparkle, and Surecrop were examined for their fungal content. Crowns contained representatives of 43 genera; roots contained 38, of which 36 were in both crowns and roots. Strawberry foliar and fruit pathogens were present in a relatively small number of the crowns and roots. In general, Chaetomium spp. and Fusarium spp. were the most prevalent. Chaetomium cochliodes was more prevalent in Cavalier and Redcoat, the varieties most susceptible to root rot in the field, than in the other varieties. The crowns and roots of apparently healthy, dormant strawberry plants contained a fungal flora similar to that associated with the black root rot complex.One fungus, Varicosporium elodeae, isolated from strawberry plants has not previously been reported in Canada.

scholarly journals Evaluation of Strawberry Genotypes for Tolerance to Black Root Rot

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 889D-889
Author(s):  
Chrislyn A. Drake* ◽  
James F. Hancock
Keyword(s):  
Methyl Bromide ◽  
Root Rot ◽  
Current Method ◽  
Pratylenchus Penetrans ◽  
Black Root Rot ◽  
Fungal Organisms ◽  
Structural Roots ◽  
Four Blocks ◽  
Serious Disease ◽  
Root Health

Black root rot is a serious disease of strawberry (Fragaria ×ananassa Duch.) that causes the death of feeder roots, the degradation and blackening of structural roots, and an overall decrease in plant vigor and productivity. The causal organisms of black root rot are Rhizoctonia fragariae, Pythium sp. and Pratylenchus penetrans (the root lesion nematode). Each organism alone can cause extensive damage to strawberry roots, but studies have shown that black root rot may be more severe when all organisms are present, indicating there is an interaction between the fungal organisms and the nematode. The current method of control for black root rot is methyl-bromide fumigation; however, methyl bromide is to be phased out by 2005, and it is not very effective in perennial matted-row systems. The objectives of the study are to measure levels of tolerance to black root rot in 21 strawberry genotypes. The genotypes were planted in four blocks each of methyl-bromide fumigated and non-fumigated soil, and were evaluated for crown, runner, and inflorescence number; yield; average berry weight; and root health. `Cavendish', `Kent', `Midway' and `Winona' showed the highest degree of tolerance, while `Jewel', `Mesabi', and LH50-4 (a F. virginiana genotype) were the poorest performers.

scholarly journals Breeding for Increased Tolerance to Black Root Rot in Strawberry

HortScience ◽  
2008 ◽  
Vol 43 (6) ◽  
pp. 1698-1702
Author(s):  
Chrislyn Ann Particka ◽  
James F. Hancock
Keyword(s):  
Genetic Variability ◽  
Root Rot ◽  
Fungal Pathogens ◽  
Pratylenchus Penetrans ◽  
Black Root Rot ◽  
Metam Sodium ◽  
Yield Parameters ◽  
Structural Roots ◽  
Strawberry Cultivars ◽  
Mating Scheme

Black root rot (BRR) is a widespread disease of strawberry (Fragaria ×ananassa) that causes the death of feeder roots and the degradation of structural roots resulting in an overall decrease in productivity. Black root rot is primarily caused by Rhizoctonia fragariae Husain and W.E. McKeen, Pythium Pringsh., and Pratylenchus penetrans (Cobb) Filipjev and Schuurmans Stekhoven. A previous study identified varying levels of tolerance to BRR in strawberry cultivars with some having high levels of tolerance. In this study, progeny populations were created to determine the amount of genetic variability for BRR tolerance. Genotypes with high, intermediate, and low tolerance to BRR were crossed in a diallel mating scheme, progeny were planted in Vapam (metam sodium)-fumigated and nonfumigated soil, and were analyzed for yield parameters. The results showed significant differences for both treatment and family, but not for the interaction between treatment and family. Pathogen analysis indicated presence of fungal pathogens and nematodes in both fumigated and nonfumigated soil.

The trend of the male–female performance differential in athletics, swimming and cycling 1948–76

1977 ◽  
Vol 9 (3) ◽  
pp. 325-338 ◽  
Author(s):  
K. F. Dyer
Keyword(s):  
Short Duration ◽  
Time Trial ◽  
Relative Performance ◽  
The Other ◽  
Performance Difference ◽  
Female Performance ◽  
Long Duration ◽  
Better Than ◽  
Main Change

SummaryThe average male–female performance difference in the three sports of track athletics, swimming and time trial cycling are examined between the years 1948 and 1976. During this period females have gradually come to participate in a much larger number of events, particularly those of longer duration. In each of these three sports, women's performances in relation to men's have more or less continuously improved and it appears that if the changes between 1948 and 1976 are maintained, average female performance will equal that of males for all events currently competed in by both sexes in these sports at some time during the next century. Estimates as to when, precisely, this will occur vary somewhat according to the basis on which the calculations are made. The other main change evident during these years is that in all three sports women's performances relative to men's for events of long duration have become as good or better than their relative performance at events of short duration.

scholarly journals (369) Field and Greenhouse Evaluation of Strawberry Genotypes for Tolerance to Black Root Rot Pathogens

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1058B-1058
Author(s):  
Chrislyn A. Drake ◽  
James F. Hancock
Keyword(s):  
Nova Scotia ◽  
Methyl Bromide ◽  
Root Rot ◽  
Current Method ◽  
Breeding Program ◽  
Fragaria Ananassa ◽  
Black Root Rot ◽  
Greenhouse Evaluation ◽  
Structural Roots ◽  
Four Blocks

Black root rot is a widespread disease of strawberry (Fragaria×ananassa Duchnesne) that causes the death of feeder roots and the degradation of structural roots. The major causal organisms of black root rot include Rhizoctonia fragariae Husain and W.E. McKeen, Pythiumspp. and Pratylenchuspenetrans(Cobb) Filipjev and Schuurmans Stekhoven. The current method of control for black root rot is methyl-bromide fumigation; however, methyl bromide is scheduled to be phased out in 2005, and its effects are short-lived in matted-row systems. The objectives of the study were to measure levels of tolerance to black root rot in 20 strawberry genotypes and to determine which pathogens were present in the soil. The genotypes were planted in four blocks each of methyl-bromide fumigated and nonfumigated soil, and were evaluated for crown number, number of flowers per crown, yield, and average berry weight over two years. The results showed that all three pathogens were present in the field, and that there was a significant genotype × fumigation interaction for yield and crown number in both years. The cultivars Bounty, Cabot, and Cavendish, all released from the breeding program in Nova Scotia, displayed tolerance to the pathogens that cause BRR. Greenhouse studies were conducted using a subset of the genotypes to determine if any one pathogen causes more damage than others, and to determine if susceptibility to a particular pathogen varies between genotypes.

scholarly journals Field Evaluation of Strawberry Genotypes for Tolerance to Black Root Rot on Fumigated and Nonfumigated Soil

2005 ◽  
Vol 130 (5) ◽  
pp. 688-693 ◽  
Author(s):  
Chrislyn A. Particka ◽  
James F. Hancock
Keyword(s):  
Nova Scotia ◽  
Methyl Bromide ◽  
Root Rot ◽  
Current Method ◽  
Field Evaluation ◽  
Breeding Program ◽  
Pratylenchus Penetrans ◽  
Black Root Rot ◽  
Structural Roots ◽  
Four Blocks

Black root rot (BRR) is a widespread disease of strawberry (Fragari×ananassa Duchnesne) that causes the death of feeder roots and the degradation of structural roots. The major causal organisms of BRR include Rhizoctonia fragariae Husain and W.E. McKeen, Pythium Pringsh., and Pratylenchus penetrans (Cobb) Filipjev and Schuurmans Stekhoven. The current method of control for black root rot is methyl-bromide fumigation; however, methyl bromide is scheduled to be phased out in 2005, and its effects are short-lived in matted-row systems. The objectives of the study were to measure levels of tolerance to BRR in 20 strawberry genotypes and to determine which pathogens were present in the soil. The genotypes were planted in four blocks each of methyl-bromide fumigated and nonfumigated soil, and were evaluated for crown number, number of flowers per crown, yield, and average berry weight over 2 years. The results showed that all three pathogens were present in the field, and that there was a significant genotype × fumigation interaction for yield and crown number in both years. The cultivars Bounty, Cabot, and Cavendish, all released from the breeding program in Nova Scotia, displayed tolerance to the pathogens that cause BRR.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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