PYTHIUM ROT OF SAINTPAULIA, THE AFRICAN VIOLET

1958 ◽  
Vol 36 (6) ◽  
pp. 843-863
Author(s):  
H. S. Thompson
Keyword(s):  
Prolonged Exposure ◽  
Pythium Ultimum ◽  
Crown Rot ◽  
Healthy Plant ◽  
Infected Leaf ◽  
Infested Soil ◽  
Rooted Cuttings ◽  
Wide Range ◽  
Root And Crown Rot ◽  
Very High

Many fungi and bacteria were isolated from African violets affected with root and crown rot, but, of these, Pythium ultimum Trow was the only organism that proved to be pathogenic to this host. P. ultimum readily infected leaf cuttings, rooted cuttings, and the petioles and leaves of plants when these were in contact with moist infested soil. Inoculum placed against the crown of a healthy plant also caused infection, but the lesion developed slowly and usually only a small amount of tissue was decayed. On the other hand, when the crowns and roots of healthy plants were set in infested soil they remained healthy; but they became predisposed to attack when they were subjected to prolonged exposure to light of very high intensity or when the roots were infested with nematodes (Meloidogyne sp.). Alternating periods of overwatering and drying did not increase the susceptibility of these healthy plants. When young plants, large enough to be planted singly in soil, were allowed to remain in vermiculite, a nonnutritive substrate, until they yellowed and were then planted in infested soil, they became infected and completely decayed. However, plants at least a year old that had been placed in vermiculite until they yellowed and were then planted in infested soil did not become infected.Infection and decay of leaf or rooted cuttings caused by P. ultimum occurred readily throughout the range of 10°–30 °C. The disease also occurred over a wide range of soil moisture, but was favored by the higher levels.When leaf cuttings and rooted cuttings of 30 varieties of African violets were planted in infested soil, all varieties proved susceptible.

scholarly journals Influence of Chloride and Nitrogen Form on Rhizoctonia Root and Crown Rot of Table Beets

Plant Disease ◽  
1997 ◽  
Vol 81 (6) ◽  
pp. 635-640 ◽  
Author(s):  
Wade H. Elmer
Keyword(s):  
Dry Weight ◽  
Anastomosis Group ◽  
Crown Rot ◽  
Infested Soil ◽  
Nitrogen Form ◽  
Root Yield ◽  
Field Soils ◽  
Root And Crown Rot ◽  
The Mean ◽  
Group 2

The effect of NaCl combined with Ca(NO3)2 or (NH4)2SO4 was examined on table beets (Beta vulgaris) in the presence and absence of Rhizoctonia solani (anastomosis group 2-2), the cause of Rhizoctonia root and crown rot. Transplants of cvs. Detroit Dark Red and Early Wonder grown in the greenhouse in infested soils and fertilized with Ca(NO3)2 (10 mmol of N) were 32% larger in dry weight than plants treated with (NH4)2SO4 (10 mmol of N). In noninfested soils, a 17% increase in dry weights was observed for plants treated with Ca(NO3)2 compared to plants that were fed (NH4)2SO4. When NaCl (0.17 mmol) was applied, the mean dry weight sincreased 40% in noninfested soil and 12% in infested soil compared to plants that received no NaCl. No significant interaction occurred between N fertilizer and NaCl in greenhouse trials. However, in field soils infested with R. solani, NaCl (560 kg/ha) combined with (NH4)2SO4 (112kg of N per ha) produced 26 to 47% more root yield than when (NH4)2SO4 was used alone. Inthe absence of NaCl, Ca(NO3)2 suppressed disease more than (NH4)2SO4, but adding NaCl to Ca(NO3)2 did not increase yield more than Ca(NO3)2 alone. The Cl salts KCl, CaCl2, and MgCl2did not significantly differ from NaCl in their ability to increase the dry weight of beets grownin infested soils. Leaf and root analyses revealed that (NH4)2SO4 applications increased N, P, S, and Mn in tissue more than Ca(NO3)2 applications. Applying NaCl increased tissue levels of Na, Cl, and Mn more than in plants that were not fed NaCl. All of the Cl salts had the effect of increasing concentrations of Cl and Mn in the plant. There was no evidence that the Na ion was disease suppressive. Chloride, however, may be of use in disease management of Rhizoctonia root and crown rot of table beets.

scholarly journals Characterization of Oomycete Species Associated With Root and Crown Rot of English Walnut in Chile

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 691-696 ◽  
Author(s):  
Jeannette Guajardo ◽  
Sebastián Saa ◽  
Natalia Riquelme ◽  
Gregory Browne ◽  
Cristian Youlton ◽  
...  
Keyword(s):  
Phytophthora Cinnamomi ◽  
Juglans Regia ◽  
Pythium Ultimum ◽  
Crown Rot ◽  
Root Rots ◽  
Root And Crown Rot ◽  
Pathogenicity Tests ◽  
English Walnut ◽  
Crown And Root Rot ◽  
Root Tissues

English (Persian) walnut (Juglans regia) trees affected by root and crown rot were surveyed in five regions of central Chile between 2015 and 2017. In each region, nine orchards, ranging from 1 to 21 years old, were randomly selected and inspected for incidence and severity of tree decline associated with crown and root rot. Soil and symptomatic crown and root tissues were collected and cultured in P5ARP semiselective medium to isolate potential oomycete pathogens, which were identified through morphology and molecularly using ITS sequences in the rDNA gene and beta tubulin gene. The most frequently isolated species was Phytophthora cinnamomi. Pathogenicity tests were conducted with representative oomycete isolates. P. cinnamomi, P. citrophthora, and Pythium ultimum were all pathogenic in J. regia. Nevertheless, only P. cinnamomi and P. citrophthora were pathogenic to English walnut. Py. ultimum caused limited levels of root damage to English walnut seedlings. Our research indicates that as the Chilean walnut industry has expanded, so have walnut crown and root rots induced by oomycetes.

scholarly journals Population Structure of Pythium ultimum from Greenhouse Floral Crops in Michigan

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 859-867 ◽  
Author(s):  
Johanna Del Castillo Múnera ◽  
Lina M. Quesada-Ocampo ◽  
Alejandro Rojas ◽  
Martin I. Chilvers ◽  
Mary K. Hausbeck
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Control Strategies ◽  
Ornamental Plants ◽  
Infected Plant ◽  
Pythium Ultimum ◽  
Crown Rot ◽  
Common Source ◽  
Root And Crown Rot ◽  
Pathogen Populations

Pythium ultimum causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of P. ultimum in Michigan floriculture crops, simple sequence repeats (SSRs) were developed using the previously published P. ultimum predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers. The average unbiased Simpson’s index (λu, 0.95), evenness (E5, 0.56), and recovery of 12 major clones out of the 65 multilocus genotypes obtained, suggests that P. ultimum is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum populations. Finally, the presence of common genotypes among counties suggests that there is an exchange of infected plant material among greenhouse facilities, or that there is a common source of inoculum coming to the region. Continued monitoring of pathogen populations will enhance our understanding of population dynamics of P. ultimum in Michigan and facilitate improvement of control strategies.

scholarly journals Phytophthora Root and Collar Rot of Paulownia, a New Disease for Europe

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1664
Author(s):  
Francesco Aloi ◽  
Mario Riolo ◽  
Federico La Spada ◽  
Gaetano Bentivenga ◽  
Salvatore Moricca ◽  
...  
Keyword(s):  
Irrigation Management ◽  
Morphological Characteristics ◽  
Stem Bark ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Infested Soil ◽  
Soil P ◽  
Rdna Its ◽  
Rdna Its Sequences ◽  
Root And Crown Rot

Paulownia species are fast growing trees native to China, which are being grown in managed plantings in several European countries for the production of wood and biomasses. In 2018, wilting, stunting, leaf yellowing, and collapse, as a consequence of root and crown rot, were observed in around 40% of trees of a 2-year-old planting of Paulownia elongata × P. fortunei in Calabria (Southern Italy). Two species of Phytophthora were consistently recovered from roots, basal stem bark, and rhizosphere soil of symptomatic trees and were identified as Ph. nicotianae and Ph. palmivora on the basis of both morphological characteristics and phylogenetic analysis of rDNA ITS sequences. Koch’s postulates were fulfilled by reproducing the symptoms on potted paulownia saplings transplanted into infested soil or stem-inoculated by wounding. Both Phytophthora species were pathogenic and caused root rot and stem cankers. Even though P. palmivora was the only species recovered from roots of naturally infected plants, in pathogenicity tests through infested soil P. nicotianae was more virulent. This is the first report of Phytophthora root and crown rot of a Paulownia species in Europe. Strategies to prevent this emerging disease include the use of healthy nursery plants, choice of well-drained soils for new plantations, and proper irrigation management.

scholarly journals First Report of Root and Crown Rot Caused by Phytophthora cinnamomi Affecting Native Stands of Arctostaphylos myrtifolia and A. viscida in California

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1395-1395 ◽  
Author(s):  
T. J. Swiecki ◽  
E. A. Bernhardt ◽  
M. Garbelotto
Keyword(s):  
Sierra Nevada ◽  
Native Species ◽  
Phytophthora Cinnamomi ◽  
Crown Rot ◽  
Infested Soil ◽  
Mixed Stands ◽  
First Report ◽  
Root And Crown Rot ◽  
Dead Plant ◽  
Natural Stands

Ione manzanita (Arctostaphylos myrtifolia) is a rare, endemic, evergreen shrub restricted to Ione formation soils (infertile, acidic, sedimentary oxisols) in the foothills of the Sierra Nevada. The widely distributed A. viscida (whiteleaf manzanita) intermixes with A. myrtifolia at the margins of Ione formation soils. In 2002, we observed extensive mortality within two mixed stands of A. myrtifolia and A. viscida near Ione, CA. At one site, nearly all plants of both species in a 0.25-ha area had died recently. At a second site, most of the A. myrtifolia and A. viscida plants on several hectares died at least 5 years earlier. Dying plants of both species exhibited wilting and desiccation of the foliage; dark brown discoloration and necrosis of the root crown, taproot, and some large roots; and loss of fine roots. Plants of all age classes were affected. We consistently isolated a Phytophthora sp. from symptomatic plants of both species using PARP (1) and acidified potato dextrose agar. We recovered the same Phytophthora sp. from soil collected under dead plants using green pears to bait flooded soil samples. The pathogen was not recovered from soil collected under healthy plants 50 m from the nearest dead plant. Based on the morphology of the hyphae, chlamydospores, sporangia, and the sequence of the internal transcribed spacer rDNA, we identified the pathogen as P. cinnamomi Rands (GenBank Accession No. AY267370; ATCC No. MYA-2989). To test pathogenicity, we poured zoospore suspensions (4 × 104 zoospores per pot) on the soil of eight pots with rooted A. myrtifolia cuttings and four pots with rooted A. viscida cuttings (1 14-month-old plant per pot). The soil in inoculated and uninoculated control pots (eight A. myrtifolia and two A. viscida) was flooded for 20 to 23 h. All inoculated A. myrtifolia developed severe root and crown rot, and seven of eight died within 17 days. All inoculated A. viscida developed severe root rot, and three of four developed 5- to 10-cm long basal cankers. After 17 days, we isolated P. cinnamomi from inoculated A. myrtifolia (eight of eight) and A. viscida (two of four) but not from controls, which remained healthy. We tested pathogenicity in native soil by transplanting rooted cuttings (eight A myrtifolia and six A. viscida) into pots of naturally infested soil from one of the disease centers. Controls (four and three plants, respectively) were planted in soil collected from under healthy plants. Pots were flooded for 12 to 13 h for 11 days (A. myrtifolia) or 6 weeks (A. viscida) after transplanting. All plants grown in naturally infested soil developed root and crown rot, and all A. myrtifolia and one A. viscida died within 5 weeks of transplanting. Plants grown in field soil collected near healthy plants remained asymptomatic. We isolated P. cinnamomi from all eight A. myrtifolia and three A. viscida plants grown in infested soil but not from the controls. To our knowledge, this is the first report of root and crown rot caused by P. cinnamomi on A. myrtifolia and A. viscida. P cinnamomi was first isolated in the state in 1942 (2), but it has not previously been reported to caused significant mortality in natural stands of California native species. This disease will significantly impact conservation of the already threatened A. myrtifolia. References: (1) D. C. Erwin and O. K. Ribeiro, Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN 1996. (2) V. A. Wager. Hilgardia 14:519, 1942.

Phytophthora cactorum. [Descriptions of Fungi and Bacteria].

1966 ◽  
Author(s):  
G. M. Waterhouse
Keyword(s):  
Geographical Distribution ◽  
Stem Canker ◽  
Fruit Trees ◽  
Crown Rot ◽  
Fruit Rot ◽  
Infested Soil ◽  
Apple Orchards ◽  
Phytophthora Cactorum ◽  
Collar Rot ◽  
Wide Range

Abstract A description is provided for Phytophthora cactorum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a very wide range of host plants embracing 54 families (particularly Rosaceae) and over 150 genera (Nienhaus, 1960; Rangaswami, 1962) including ash, beech, cherry, conifers, apple, pear, apricot, strawberry, cucurbits, eggplant, cacti, gooseberry, rhododendron, lilac, ginseng, rhubarb, avocado, birch, maple and oak. DISEASES: Damping-off of seedlings including ash, beech, cherry and conifers; fruit rot of apple, pear, apricot, strawberry (leather rot), cucurbits and eggplant; leaf and stem rot of cacti, gooseberry, rhododendron, lilac, ginseng and rhubarb; collar rot and crown rot of apple and other fruit trees stem canker of avocado, birch, maple and oak; root rots in general. GEOGRAPHICAL DISTRIBUTION: Widespread in tempetate areas (CMI Map 280). TRANSMISSION: Soil-borne. Widely distributed in soils of apple orchards affected with collar rot (35: 685; 37: 132). Strawberry fruit in unmulched beds and wind-fall apples and pears on the ground frequently become infected by contact with infested soil (4: 101; 35: 685) where the pathogen may occur to a depth of 50 cm and persist for as long as 15 yr. in ploughland previously under apple orchards (42: 75). This has been partially explained by the irregular germination of oospores which require a dormant period (Blackwell, 1943; Legge, 1952). Apple fruit and gooseberry shoot infection are most frequent on lower branches subject to rain-splash which carry zoospores (41: 49). Long periods of rain, heavy dews, fog and high soil moisture favour the spread of the pathogen (39: 250; 45, 2553; 22: 30-31; 42: 391).

scholarly journals First Report of Root and Crown Rot of Sage Caused by Phytophthora cryptogea in Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (10) ◽  
pp. 1176-1176 ◽  
Author(s):  
S. O. Cacciola ◽  
A. Pane ◽  
F. Raudino ◽  
S. Davino
Keyword(s):  
Mating Type ◽  
Sandy Loam ◽  
Ornamental Plants ◽  
Electrophoretic Pattern ◽  
Crown Rot ◽  
Infested Soil ◽  
Mycelium Growth ◽  
First Report ◽  
Electrophoretic Patterns ◽  
Root And Crown Rot

Sages are cultivated as aromatic and ornamental plants in Italy and represent the common name of certain species of Salvia and Phlomis (family Lamiaceae). In Sicily (southern Italy) during the summer of 2001, ≈40% of 1,400 2-year-old landscape plants of S. leucantha Cav. (Mexican bush sage or velvet sage) showed symptoms of stunting, chlorosis, and gradual dieback or sudden wilt, which are associated with root and crown rot. Plants were supplied by a commercial nursery, transplanted from pots in the spring, and irrigated using a trickle system. Phytophthora was isolated consistently from roots and basal stems of symptomatic plants on a BNPRAH medium (2). The species was identified as P. cryptogea Pethybr. & Laff., primarily on the basis of morphological and cultural characteristics. Five representative single-hypha isolates were characterized. On potato dextrose agar, they formed colonies with a slight petaloid pattern. Cardinal temperatures for mycelium growth were 2°C, minimum; 25°C, optimum; and 30 to 35°C, maximum. Hyphal swellings were abundant in aqueous culture. Sporangia were obpyriform, persistent, nonpapillate, and proliferous (2). All isolates were the A1 mating type and formed oogonia, amphigynous antheridia, and oospores in dual cultures with reference isolates of the A2 mating type of P. cryptogea and P. drechsleri. Identification was confirmed by electrophoresis of mycelium proteins on a polyacrylamide slab gel (1). Electrophoretic patterns of total soluble proteins from the sage isolates were identical or very similar to those from 10 reference isolates of P. cryptogea from various hosts, including isolate IMI 180615 (ex-type isolate). Conversely, the electrophoretic pattern of the isolates of P. cryptogea from sage was clearly distinct from those from reference isolates of other species included in Waterhouse's taxonomic group VI. Esterase (EC 3.1.1.2.) zymograms of the sage isolates corresponded to those of isolates of P. cryptogea included in electrophoretic group 2 (1). The pathogenicity of a representative isolate of P. cryptogea from sage was tested in the greenhouse using 4-month-old plants of Mexican bush sage. Inoculum was produced on a mixture of vermiculite and autoclaved oat seeds (4) and mixed with steam-sterilized sandy loam soil at a concentration of 4% (vol/vol). Plants were transplanted in pots (12 cm diameter) filled with infested soil; control plants were grown in pots containing noninfested soil. After transplanting, all pots were placed in shallow trays filled with water for 24 h to saturate the soil. All plants grown in infested soil showed extensive root necrosis and dieback ≈30 days after transplanting, and P. cryptogea was reisolated from roots of symptomatic plants. Control plants did not develop symptoms. Root and crown rot of sage caused by P. cryptogea has been reported previously in California (3). To our knowledge, this is the first report of P. cryptogea on sage in Italy. Root rot caused by P. cryptogea may be a potential problem for commercial cultivation of sage as no serious disease of this plant has been reported in Italy so far. References: (1) S. O. Cacciola et al. EPPO Bull. 20:47, 1990. (2) D. C Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul MN. 1996. (3) S. T. Koike et al. Plant Dis. 81:959, 1997. (4) E. Sánchez-Hernández et al. Plant Dis. 85:411, 2001.

TEM study of boron additions to cobalt aluminide

1988 ◽  
Vol 46 ◽  
pp. 546-547
Author(s):  
Gerald B. Feldewerth
Keyword(s):  
High Temperature ◽  
Turbine Engines ◽  
Major Drawback ◽  
University Of Missouri ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Wide Range ◽  
Ordered Alloys ◽  
The University ◽  
Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

Features of the Christian values ​​system

2004 ◽  
pp. 21-29
Author(s):  
G.V. Pyrog
Keyword(s):  
Public Opinion ◽  
Religious Beliefs ◽  
Religious Values ◽  
Direct Influence ◽  
Moral Norms ◽  
Value System ◽  
Christian Religion ◽  
Mass Consciousness ◽  
Wide Range ◽  
Very High

In domestic scientific and public opinion, interest in religion as a new worldview paradigm is very high. Today's attention to the Christian religion in our society is connected, in our opinion, with the specificity of its value system, which distinguishes it from other forms of consciousness: the idea of ​​God, the absolute, the eternity of moral norms. That is why its historical forms do not receive accurate characteristics and do not matter in the mass consciousness. Modern religious beliefs do not always arise as a result of the direct influence of church preaching. The emerging religious values ​​are absorbed in a wide range of philosophical, artistic, ethical ideas, acting as a compensation for what is generally defined as spirituality. At the same time, the appeal to Christian values ​​became very popular.

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