STUDIES OF CROWN ROT OF APPLE TREES

1942 ◽  
Vol 20c (9) ◽  
pp. 457-490 ◽  
Author(s):  
Maurice F. Welsh
Keyword(s):  
Soil Moisture ◽  
Apple Tree ◽  
Disease Incidence ◽  
Antagonistic Effect ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Additional Information ◽  
Two Factors ◽  
Below Ground ◽  
Old Trees

The form of apple tree crown rot that occurs in the irrigated orchards of British Columbia is confined to the below-ground bark tissues of the tree. It has been encountered in trees of all ages and of all the commercial varieties.Proof is given that this crown rot is caused by the fungus Phytophthora cactorum (L. & C.) Schroet. Typical symptoms of the disease have been reproduced in over 200 trees of various ages as a result of their inoculation with this fungus. Isolation has been possible only from the margins of active lesions, and has proved difficult even from these tissues. There is evidence that the activity of P. cactorum is inhibited in rotted tissues by the antagonistic effect of one or more secondary organisms.The influence of soil moisture and temperature on disease incidence has been studied by field observations and by the inoculation of two-year—old trees under controlled conditions in Wisconsin tank equipment in the greenhouse. The effects of these two factors seem to be interrelated, with the highest incidence of disease in an almost saturated soil at the highest temperature imposed, 32 °C. The influence of soil moisture is exerted particularly in the subsoil, rather than in the locus of crown rot attack.Certain varieties of apple have been found to vary in their resistance to crown rot. Deep wounds have proved necessary to allow entry of the fungus into bark tissues.The additional information now available is being utilized in a search for improved means of combating the disease.

scholarly journals Incidence and Severity of Crown and Root Rots on Four Apple Rootstocks Following Exposure to Phytophthora Species and Waterlogging

1993 ◽  
Vol 118 (1) ◽  
pp. 63-67 ◽  
Author(s):  
W.F. Wilcox
Keyword(s):  
Root Rot ◽  
Shoot Growth ◽  
Disease Susceptibility ◽  
Disease Incidence ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Apple Rootstocks ◽  
Root Rots ◽  
Potting Medium

Plants of four apple (Malus ×domestica Borkh.) rootstock clones, M.7, M.26, MM.111, and Ottawa (O.) 3, were grown in unamended potting medium or in the same medium infested with Phytophthora cactorum (Leb. & Cohn) Schroet., P. cambivora (Petri) Buisman, P. cryptogea Pethyb. & Laff., or P. megasperma Drechsler, causal agents of crown and root rots. Plants were flooded for either 0, 24, 48, or 72 h every 7 days for 4 months, then assessed for disease incidence and severity. Averaged across all pathogens and rootstocks, mean crown rot incidences were 2.5%, 6.3%, 19%, and 50% following weekly flooding periods of 0, 24, 48, and 72 h, respectively; when averaged across all rootstocks and flooding treatments, mean incidences of crown rot caused by P. cryptogea, P. cactorum, P. cambivora, and P. megasperma were 36%, 26%, 15%, and 8.8%, respectively; when averaged across all four pathogens, mean crown rot incidences after 72 h of flooding were 40%, 45%, 50%, and 75% for M.26, 0.3, M.7, and MM.111, respectively. In contrast, 72-h flooding periods in the absence of a pathogen were least detrimental to growth of MM.111 clones and most detrimental to shoot growth of M-26. Exceptions to general trends were reflected by statistical interactions among pathogens, rootstocks, and flooding durations, e.g., after 72-h floodings, 0.3 was the rootstock with the greatest amount of root rot caused by P. cryptogea but the least amount caused by P. megasperma. Differential disease susceptibility among rootstocks appeared greatest with respect to P. cactorum and least with respect to P. cryptogea.

scholarly journals The Role of Averaging for Improving Sea Surface Salinity Retrieval from the Soil Moisture and Ocean Salinity (SMOS) Satellite and Impact of Auxiliary Data

2007 ◽  
Vol 24 (2) ◽  
pp. 255-269 ◽  
Author(s):  
Sabine Philipps ◽  
Christine Boone ◽  
Estelle Obligis
Keyword(s):  
Soil Moisture ◽  
Sensitivity Study ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Global Ocean ◽  
Surface Salinity ◽  
Auxiliary Data ◽  
Additional Information ◽  
Ocean Salinity

Abstract Soil Moisture and Ocean Salinity (SMOS) was chosen as the European Space Agency’s second Earth Explorer Opportunity mission. One of the objectives is to retrieve sea surface salinity (SSS) from measured brightness temperatures (TBs) at L band with a precision of 0.2 practical salinity units (psu) with averages taken over 200 km by 200 km areas and 10 days [as suggested in the requirements of the Global Ocean Data Assimilation Experiment (GODAE)]. The retrieval is performed here by an inverse model and additional information of auxiliary SSS, sea surface temperature (SST), and wind speed (W). A sensitivity study is done to observe the influence of the TBs and auxiliary data on the SSS retrieval. The key role of TB and W accuracy on SSS retrieval is verified. Retrieval is then done over the Atlantic for two cases. In case A, auxiliary data are simulated from two model outputs by adding white noise. The more realistic case B uses independent databases for reference and auxiliary ocean parameters. For these cases, the RMS error of retrieved SSS on pixel scale is around 1 psu (1.2 for case B). Averaging over GODAE scales reduces the SSS error by a factor of 12 (4 for case B). The weaker error reduction in case B is most likely due to the correlation of errors in auxiliary data. This study shows that SSS retrieval will be very sensitive to errors on auxiliary data. Specific efforts should be devoted to improving the quality of auxiliary data.

A soil moisture meter. Depending on the “capillary pull” of the soil. With illustrations of its use in fallow land, grass orchard, and irrigated orchards

1935 ◽  
Vol 25 (3) ◽  
pp. 326-343 ◽  
Author(s):  
W. S. Rogers
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Continuous Measurement ◽  
Fallow Land ◽  
Soil Particles ◽  
Moisture Meter ◽  
Two Factors ◽  
Moisture Percentage ◽  
Mercury Manometer

1. A soil moisture meter which gives direct and continuous measurement of the soil moisture content is described. The instrument consists of a special porous pot filled with water, connected by a tube to a mercury manometer. The pot is buried in the soil, whose capillary pull causes the mercury to rise. The height to which the mercury rises depends on the amount of moisture in the soil, and also on the size of soil particles and the degree of compactness of the soil. (The last two factors remain constant for an instrument in one position.)2. To read actual moisture percentage each instrument has to be calibrated for the soil in which it is placed. Once this is done, all sampling and weighing is eliminated.

scholarly journals Morphological and pathogenic characterization of Fusarium oxysporum in lulo (Solanum spp.)

2021 ◽  
Vol 38 (1) ◽  
pp. 20-37
Author(s):  
Yohana Patricia Anama ◽  
Ricardo Díaz ◽  
David Esteban Duarte-Alvarado ◽  
Tulio Cesar Lagos-Burbano
Keyword(s):  
Growth Rate ◽  
Fusarium Oxysporum ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Morphological Characterization ◽  
Sources Of Resistance ◽  
Randomized Design ◽  
Two Factors ◽  
Height Increase ◽  
Genotype G1

Fusarium oxysporum is one of the most limiting fungal pathogens of lulo crop. To determine its pathogenicity, this work morphologically and pathogenically characterized F. oxysporum isolates from different lulo-growing municipalities of the Department of Nariño. Twenty isolates were evaluated through a completely randomized design with two factors and three replicates per treatment, including a control. The first factor corresponded to 20 isolates of F. oxysporum and the second to 10 lulo genotypes. The morphological characterization involved determining growth rate (GR), color (CO), mycelial type (MT), medium coloration (Mc), shape (Sh), size (S), number (N) of macroconidial (Ma) and microconidial (Mi) septa, presence of chlamydospores (PC), and chlamydospore shape (CS). Moreover, the pathogenic characterization was based on the incubation period (IP), absolute growth rate (AGR), disease severity (DS), disease incidence (I), and vascular discoloration (VD). The morphological characterization demonstrated that all isolates corresponded to F. oxysporum. For IP, genotype G1 showed the lowest average at 18 days. For AGR, genotype G2 had the lowest height increase at 0.05 cm.day-1. For DS, genotype G1 reached the highest severity level (level 9) and a disease incidence of 100%. This study provides the first report of the special form of F. oxysporum f. sp. quitoense in Nariño. Solanum hirtum, Solanum sessiliflorum, and Solanum estramonifolium were resistant to the isolates evaluated, demonstrating that wild species should be considered as sources of resistance for breeding programs aiming to obtain resistant commercial genotypes.

scholarly journals Antagonistic effectiveness of some bacteria against Fusarium graminearum causing crown rot disease on wheat (Triticum aestivum)

2021 ◽  
Vol 13 (1) ◽  
pp. 69-80
Author(s):  
Majida Hadi Mahdi Alsaady ◽  
Hussein Ali Salim ◽  
Rakib A. Al-ani ◽  
Hadi M. Aboud ◽  
Jamal Talib M Al Roubaie
Keyword(s):  
Fusarium Graminearum ◽  
Culture Method ◽  
Dry Weight ◽  
Antagonistic Effect ◽  
Crown Rot ◽  
Control Treatment ◽  
Enzyme Analysis ◽  
Dual Culture ◽  
Rot Disease

In this study, the antagonistic effect of five bacteria genera namely Bacillus, Pseudomonas, Azotobacter, Azospirillum, and Streptomyces isolated from rhizosphere of wheat were evaluated against Fusarium graminearum as potential biocontrol agents in vitro. F. graminearum was molecularly diagnosed using the Polymerase chain reaction (PCR) technique. Each bacteria were tested for the production of catalase enzyme, oxidase enzyme, analysis of starch, analyze of gelatin, and the motility, where Azotobacter, Azospirillum, and Bacillus subtilis were positive for all tested. Fungal inhibition tests were performed by using the dual culture method and agar well diffusion technique. Among them, Streptomyces and Azospirillum exhibited potent inhibition to the growth of F. graminearum (72.14% and 66.42%) respectively, followed by B.pumillus, P.fluorescens, B. subtilis and Azotobacter ( 58.28%, 43.23%, 39.71% and 35.71%) respectively as compared with the control treatment (0.0%).The dry weight of the fungus biomass was decreased with bacteria P. fluorescens, Streptomyces sp, Azotobacter sp, Azospirillum sp, B. subtilis, and B. pumillus which reached (0.114, 0.103, 0.147, 0.101, 0.143, and 0.107 g) respectively compared to the control treatment that was 0. 665 g.

scholarly journals First report of crown rot of Photinia fraseri caused by Phytophthora cactorum

2006 ◽  
Vol 55 (4) ◽  
pp. 573-573 ◽  
Author(s):  
A. M. Vettraino ◽  
L. Antonacci ◽  
L. Flamini ◽  
P. Nipoti ◽  
E. Rossini ◽  
...  
Keyword(s):  
Crown Rot ◽  
Phytophthora Cactorum ◽  
First Report

Sweetpotato root development influences susceptibility to black rot caused by the fungal pathogen Ceratocystis fimbriata

2021 ◽  
Author(s):  
Camilo Humberto Parada Rojas ◽  
Kenneth Pecota ◽  
Christie Almeyda ◽  
G. Craig Yencho ◽  
Lina Quesada-Ocampo
Keyword(s):  
Root Development ◽  
Disease Incidence ◽  
Black Rot ◽  
Wild Relative ◽  
Storage Root ◽  
Storage Roots ◽  
Ceratocystis Fimbriata ◽  
Breeding Lines ◽  
Below Ground ◽  
Storage Root Development

Black rot of sweetpotato caused by Ceratocystis fimbriata, is an important reemerging disease threatening sweetpotato production in the United States. This study assessed disease susceptibility of the storage root surface, storage root cambium, and slips (vine cuttings) of 48 sweetpotato cultivars, advanced breeding lines, and wild relative accessions. We also characterized the effect of storage root development on susceptibility to C. fimbriata. None of the cultivars examined at the storage root level were resistant, with most cultivars exhibiting similar levels of susceptibility. In storage roots, Jewel and Covington were the least susceptible and significantly different from White Bonita, the most susceptible cultivar. In the slip, significant differences in disease incidence were observed for above and below ground plant structures among cultivars, advanced breeding lines, and wild relative accessions. Burgundy and Ipomoea littoralis displayed less below ground disease incidence as compared to NASPOT 8, Sunnyside and LSU-417, the most susceptible cultivars. Correlation of black rot susceptibility between storage roots and slips was not significant, suggesting that slip assays are not useful to predict resistance in storage roots. Immature, early developing storage roots were comparatively more susceptible than older, fully developed storage roots. The high significant correlation between storage root cross-section area and cross-sectional lesion ratio suggests the presence of an unfavorable environment for C. fimbriata as the storage root develops. Incorporating applications of effective fungicides at transplanting and during early storage root development when sweetpotato tissues are most susceptible to black rot infection may improve disease management efforts.

scholarly journals Meristem culture for the elimination of the strawberry crown rot pathogen Phytophthora cactorum

2011 ◽  
Vol 1 (3) ◽  
pp. 129-136 ◽  
Author(s):  
A.B. Whitehouse ◽  
C.L. Govan ◽  
K.J. Hammond ◽  
D.J. Sargent ◽  
D.W. Simpson
Keyword(s):  
Crown Rot ◽  
Meristem Culture ◽  
Phytophthora Cactorum

Water relations of Pinus radiata under plantation conditions

1964 ◽  
Vol 12 (2) ◽  
pp. 111 ◽  
Author(s):  
RD Johnston
Keyword(s):  
Soil Moisture ◽  
Late Summer ◽  
Soil Surface ◽  
Experimental Period ◽  
Mean Value ◽  
Soil Conditions ◽  
Dry Period ◽  
Autumn Leaf ◽  
Leaf Water Deficit ◽  
Old Trees

Two groups of four 9-year-old trees of P. radiata were isolated "droughted" by lining trenches, and covering the soil surface, with plastic film. Two similar groups served as controls. Soils in the control plots dried out to above pF 4.2 during a 6 weeks' drought in late summer, and again in a shorter dry period in autumn. Leaf water deficit (L.W.D.) was correlated with soil moisture tension (S.M.T.) while there was available soil moisture, and rose during the drought to a maximum of 22.8. Autumn rain which wet the upper part of the soil profile reduced the L.W.D. to a mean value of 12. In the droughted plots, S.M.T. rose to above pF 4.2 in the first six weeks and remained high for the rest of the experimental period. During normal weather with occasional light falls of rain, L.W.D. was maintained at about 17-significantly higher than the corresponding values for the control plots. With the onset of dry weather, L.W.D. in the droughted plots rose further, but not significantly higher than in the controls. L.W.D. decreased when rain occurred, although less than in the control plots. P. radiata is able to maintain moderate turgidity in its needles, even under very dry soil conditions, as long as there is frequent precipitation sufficient to wet the foliage.

Effects of Lysobacter antibioticus HS124, an effective biocontrol agent against Fusarium graminearum, on crown rot disease and growth promotion of wheat

2019 ◽  
Vol 65 (12) ◽  
pp. 904-912 ◽  
Author(s):  
Yun-Tae Kim ◽  
Sararat Monkhung ◽  
Yong Seong Lee ◽  
Kil Yong Kim
Keyword(s):  
Fusarium Graminearum ◽  
Mycelial Growth ◽  
Growth Promotion ◽  
Disease Incidence ◽  
Culture Method ◽  
Microscopic Investigation ◽  
Crown Rot ◽  
Dual Culture ◽  
Rot Disease

Lysobacter antibioticus HS124 inhibited mycelial growth of Fusarium graminearum (74.66%) under the dual culture method. Microscopic investigation clearly showed that amendment with different concentrations (10%, 30%, and 50%) of HS124 bacterial culture filtrate on potato dextrose agar plates caused abnormal hyphal structures, including swelling and distortion. Its inhibition toward mycelial growth of F. graminearum was increased with increasing concentration of n-butanol crude extract of HS124. The highest inhibition (43.14%) was detected at a crude concentration of 10 mg/disc, whereas the lowest inhibition (21.57%) was observed at 2 mg/disc. Although mycelial growth of F. graminearum was promoted by volatile organic compounds (VOCs) produced by HS124 as compared with the control, these VOCs clearly decreased fungal pigmentation resulting in a reduction of fungal sporulation. Microscopic investigation revealed hyphal deformation of F. graminearum due to VOCs. These compounds also had a negative effect on spore germination of F. graminearum. In vivo evaluations demonstrated that HS124 inoculation of wheat plants reduced crown rot disease incidence by 73.70% as compared with the control. HS124 inoculation of wheat plants also promoted most of the growth characteristics compared with the control or fungicide-treated plants. Our results provide strong evidence that HS124 could control F. graminearum infections and promote growth of wheat plants as part of management strategies for crown rot disease.

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