ROOT ROTS OF THE RASPBERRY

1936 ◽  
Vol 14c (8) ◽  
pp. 306-317 ◽  
Author(s):  
G. H. Berkeley
Keyword(s):  
British Columbia ◽  
Rhizoctonia Solani ◽  
Microscopic Examination ◽  
Root Rot ◽  
Mycorrhizal Fungus ◽  
Root Rots ◽  
Pure Cultures ◽  
Fusarium Sp ◽  
Fraser Valley ◽  
Apparently Healthy

The investigations reported here are concerned with isolations from diseased raspberry roots, preliminary inoculations with isolates, and microscopic examination of naturally and artificially infected roots.The following fungi were isolated from naturally infected roots: Coniothyrium Fuckelii, Cylindrocarpon radicicola, Fusarium sp., possibly F. orthoceras, Cylindrocladium sp., Pythium spp., Rhizoctonia Solani, Rhizoctonia sp. (orchid type), and in preliminary inoculation experiments each fungus was found to be capable of producing necrotic lesions on healthy roots. Microscopic examinations of roots artificially inoculated with pure cultures of the above fungi, showed in the roots the presence of the fungus used for inoculation. In addition the "phycomycetous mycorrhizal" fungus already associated with root rot of strawberries and tobacco was observed to be almost always present in roots of affected raspberry plants, and, to a lesser extent, in apparently healthy roots from apparently normal plants. Nematodes, especially Anguillulina pratensis, the meadow nematode, were present in and on roots from certain soils, while they were absent from roots from other soils. Strawberry and raspberry seeds were sown in sterilized and non-sterilized affected soil with the result that the roots in sterilized soil appeared to be healthy, while those in the non-sterilized soil became affected with necrotic lesions.Evidence is given which shows not only that certain symptoms of raspberry root rot are similar to the symptoms of strawberry root rot, which is considered to be a major factor in the degeneration of strawberries in both Europe and America, but also that many of the fungi and nematodes generally conceded to be associated with root rots of strawberry are likewise associated with root rots of raspberry. In the Fraser Valley, British Columbia, where certain raspberry plantations appear to be heavily infected with root rots, the possibility that these root rots may play an important role in connection with the un-thriftiness of such plantations should not be overlooked.

Mermithid parasites of the mosquito Aedes vexans Meigen in British Columbia

1968 ◽  
Vol 46 (5) ◽  
pp. 1077-1079 ◽  
Author(s):  
Milan Trpiš ◽  
W. O. Haufe ◽  
J. A. Shemanchuk
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
Life Cycle ◽  
Guinea Pigs ◽  
Ovarian Development ◽  
Aedes Vexans ◽  
Healthy Female ◽  
Fraser Valley ◽  
Time Of Collection ◽  
Apparently Healthy

Newly emerged and apparently healthy female adults of Aedes vexans Meigen were collected in the Fraser Valley, British Columbia, After they had fed once on man at the time of collection and daily on guinea pigs thereafter in the laboratory, they were found to be infected with mermithid worms that developed rapidly at 25 °C. The parasites suppressed ovarian development and caused nearly 100% mortality within 10 days. They started to leave morbid hosts within 7 days. More detailed studies of the life cycle of the mermithid parasites are needed to assess their effectiveness and specificity in the biological control of A. vexans.

FUNGOUS ROOT ROTS OF THE STRAWBERRY

1934 ◽  
Vol 11 (1) ◽  
pp. 1-17 ◽  
Author(s):  
J. H. L. Truscott
Keyword(s):  
Seasonal Variations ◽  
Root Rot ◽  
Mycorrhizal Fungus ◽  
Artificial Inoculation ◽  
Microscopical Examination ◽  
Relative Importance ◽  
Root Rots ◽  
Growing Seasons ◽  
Obligate Parasites ◽  
Wild Strawberry

This paper reports the results of two years of investigation at the Horticultural Experiment Station at Vineland, Ontario, on fungi associated with the root rot of strawberries. Roots from the field were collected periodically throughout two growing seasons and were studied by direct microscopical examination and by plating methods. Hundreds of isolates from diseased roots were tested by artificial inoculation of strawberry roots, and the primary parasites were further studied. These were classed in the following genera: Pythium, Fusarium, Alternaria, Ramularia, Rhizoctonia, Verticillium and Cylindrocladium. Microscopical examination revealed three additional forms, Asterocystis, a Plasmodiophoraceous fungus and the Phycomycetous mycorrhizal fungus, which are obligate parasites of Phycomycetous type. Some of the fungi occurred more frequently than others, and there were seasonal variations in the activity of most of them. A similar root flora was encountered in wild strawberry roots, so that most of these fungi are probably indigenous. Their relative importance can be determined only by several years of observation of field material.

scholarly journals First Report of White Root Rot of Japanese Serissa Caused by Rosellinia necatrix in Taiwan

Plant Disease ◽  
2007 ◽  
Vol 91 (11) ◽  
pp. 1512-1512
Author(s):  
W. W. Hsiao ◽  
C. H. Fu ◽  
C. Y. Chen ◽  
E. J. Sun
Keyword(s):  
Root Rot ◽  
Plant Diseases ◽  
Rosellinia Necatrix ◽  
White Root Rot ◽  
First Report ◽  
Root Rots ◽  
Old Japanese ◽  
Pure Cultures ◽  
The Republic ◽  
Central Taiwan

Japanese serissa (Serissa japonica (Thunb.) Thunb.) is a very popular ornamental in Taiwan. During the summer of 2005, serissa plants in a central Taiwan nursery had decaying roots, leaf yellowing, and were wilting. Wilted plants had white fan-like mycelium under the bark. The disease caused 70% loss of seedlings at the nursery. Associated synnemata were rigid, erect, dark, setaceous, 0.8 to 2.1 mm long, 90 to 200 μm wide, and tapering to enlarged whitish gray heads composed of geniculate conidiophores and conidia. Conidia were 3.1 to 5.8 × 2.6 to 3.4 μm, unicellular, hyaline, and subglobal with a truncated base. Root rots were washed, disinfested for 1 min in 0.5% NaOCl, cut into 3 mm3 pieces, plated on Merck (Darmstadt, Germany) potato dextrose agar (PDA) amended with 100 ppm of ampicillin (Sigma, St. Louis, MO), and incubated at 24°C in the dark until hyphae emerged. Single hyphal tips were transferred to PDA, and two isolates were established as pure cultures. Mycelia were cut, stained with 1% cotton blue in lactophenol, and pear-shaped hyphal swellings adjacent to the septa were observed. According to these hyphal, synnematal, and conidial characteristics, the fungus was identified as Dematophora necatrix Hartig, the anamorph of Rosellinia necatrix Prill. Inoculum for pathogenicity tests were produced on oat-wheat medium composed of 20 ml of oat grain and 20 ml of wheat grain, mixed, and soaked in water for 3 h. The grains were placed in 200-ml flasks, autoclaved at 121°C for 30 min, inoculated with two isolates of D. necatrix separately, and grown for 14 days. Six 3-month-old Japanese serissa seedlings were grown in pots. The grain inoculum was added to unsterilized field soil and the plants were transplanted into this mix. Control plants were transplanted into a similar mix without the inoculum. Two replicates were used for a total of 24 inoculated plants and 24 control plants. All plants were kept in a growth chamber at 25 to 35°C with 20 min of irrigation per day, 12 h of irradiation, and relative humidity at more than 95%. Inoculated plants developed root rots after 1 month, and after 4 months, all plants were dead, while control plants remained healthy. D. necatrix was reisolated, hyphal characteristics confirmed, and synnemata were observed on collars of dead plants. The teleomorph was not formed by our cultures, and the identification of Rosellinia necatrix was confirmed by molecular studies. The nuclear ribosomal internal transcribed spacer (ITS) amplified with two primers, ITS1 and ITS4, from our representative isolate demonstrated 99.63, 99.81, and 99.27% similarity to two R. necatrix isolates from Japan and one R. necatrix isolate from Italy, respectively. This disease has been reported on many species of plants (1), but to our knowledge, this is the first report of white root rot of Japanese serissa seedlings caused by R. necatrix in Taiwan. Reference: (1) S. T. Su et al. List of Plant Diseases in Taiwan. The Phytopathological Society of the Republic of China, 2002.

Occurrence and importance of root rots caused by fungal pathogens on sugar beet grown in Konya province of Turkey

2020 ◽  
pp. 674-681
Author(s):  
Rıza Kaya ◽  
Meltem Avan ◽  
Cemre Aksoy ◽  
Fikret Demirci ◽  
Yakup Zekai Katircioğlu ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
Fungal Pathogens ◽  
Fusarium Culmorum ◽  
Macrophomina Phaseolina ◽  
Growth Stages ◽  
Aphanomyces Cochlioides ◽  
Root Rots ◽  
Phytophthora Spp

Sugar beet is extensively grown in Konya province of Turkey and about one third of production of Turkey is obtained from this region. Recently root rots have been observed at all the growth stages of sugar beet especially at later stages near the harvest. During 2015–2017 growing years, 866 fields were visited and diseased samples having root rot symptoms were collected. Various root rot pathogens were isolated from 691 fields; Rhizoctonia solani being the most common (15% of the fields) followed by Fusarium oxysporum, F. solani, Phoma betae, Aphanomyces cochlioides and Pythium spp. Apart from these pathogens, Fusarium culmorum, F. equiseti, F. sambucinum, F. verticillatum, unidentified Fusarium spp., Macrophomina phaseolina and Phytophthora spp. were also determined. All the fungal pathogens were isolated from both of the sugar beet growing stages of 0–12 BBCH and 31–49 BBCH, some of them being high ratios at the late stages. Some isolates of A. cochlioides, P. betae, Pythium spp., Phytophthora spp., and R. solani were highly aggressive when tested by a soil inoculum layer technique. Effects of twelve fungicides, in sixteen different combination and rate, on the most virulant and common four pathogens, A. cochlioides P. betae, Py. ultimum var. ultimum, Rhizoctonia solani, were investigated by the same technique. None of the fungicide mixes inhibited all four pathogens. Thiram + metalaxyl + hymexazol + pyraclastrobin mix sufficiently prevented disease development of the first three pathogens but not R. solani.

scholarly journals First Report of Phytophthora megasperma and Pythium irregulare As Olive Tree Root Pathogens

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1216-1216 ◽  
Author(s):  
M. E. Sánchez-Hernández ◽  
A. Ruiz-Dávila ◽  
A. Trapero-Casas
Keyword(s):  
Root Rot ◽  
Olive Tree ◽  
The United States ◽  
Damping Off ◽  
Phytophthora Megasperma ◽  
Root Rots ◽  
Foliar Symptoms ◽  
Root Pathogens ◽  
Root Necrosis ◽  
Olive Trees

Several species of the genus Phytophthora are associated with root rot and trunk cankers in olive trees (Olea europaea L.). Among them, Phytophthora megasperma has been cited as being associated with olive root rots in Greece (1). Unidentified species of Pythium and Phytophthora have also been associated with olive tree root rots in the United States. However, the status of P. megasperma and Pythium spp. as olive tree root pathogens has remained unclear. Following a 5-year period of severe drought in southern Spain, autumn-winter rainfall rates in 1996 to 1997 steadily increased in both quantity and frequency. Under these unusually wet conditions, olive trees remained waterlogged for several months. During this period, we observed foliar wilting, dieback, and death of young trees, and later found extensive root necrosis. In 46 of 49 affected plantations surveyed, P. megasperma was consistently isolated from the rotted rootlets, particularly in young (<1- to 10-year-old trees) plantations. This fungus was not detected on plant material affected by damping-off from several Spanish olive tree nurseries. The opposite situation occurred with P. irregulare. This species was not associated with rotted rootlets in the field. In contrast, it was consistently isolated from necrotic rootlets from young olive plants affected by damping-off. These plants were grown in a sand-lime-peat soil mixture under greenhouse conditions and showed foliar wilting and extensive necrosis of the root systems. Pathogenicity tests were conducted with several isolates of P. megasperma and P. irregulare on 6-month-old rooted cuttings of olive, under both weekly watering and waterlogged conditions. Under waterlogged conditions, both fungal species produced extensive root necrosis 2 weeks after inoculation that resulted in wilting of the aerial parts and rapid plant death. Waterlogged control plants remained without foliar symptoms but a low degree of root necrosis was recorded. In addition, under weekly watering conditions, plants inoculated with either species showed some degree of root rot but foliar symptoms were not evident. No differences in pathogenicity were observed within the Phytophthora or Pythium isolates. Reference: (1) H. Kouyeas and A. Chitzanidis. Ann. Inst. Phytopathol. Benaki 8:175, 1968.

Cylindrocladium root rot in Ontario bare-root nurseries: estimate of spruce seedling losses

1988 ◽  
Vol 18 (11) ◽  
pp. 1493-1496 ◽  
Author(s):  
J. Juzwik ◽  
C. Honhart ◽  
N. Chong
Keyword(s):  
Visual Field ◽  
Root Rot ◽  
Disease Incidence ◽  
White Spruce ◽  
Visual Assessment ◽  
Inoculum Density ◽  
Field Assessment ◽  
Causal Fungus ◽  
Bare Root ◽  
Apparently Healthy

Estimates of cylindrocladium root rot losses in three black and three white spruce compartments at five Ontario bare-root nurseries were determined through visual field assessment and seedling isolation. The causal fungus, Cylindrocladiumfloridanum Sob. & C.P. Seym., was isolated from 10–77% of the symptomatic and 0–28% of the apparently healthy seedlings in each compartment. In five compartments, estimates of mean incidence based on seedling isolations and visual assessment, were higher than those based on visual assessment alone. The percentage of living spruce (apparently healthy or symptomatic) estimated to be infected in each compartment was 0.1–32.7%. No fungus isolations were attempted from dead seedlings. Mortality in the plots in the six compartments was 0.02–17.7%. The correlation between the level of Cylindrocladium incidence and the inoculum density was significant (p < 0.01) in two compartments. The use of inoculum density to predict disease incidence warrants further investigation.

scholarly journals Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
The United States ◽  
Damping Off ◽  
Growth Assay ◽  
The Mean ◽  
Crown And Root Rot ◽  
Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

Efficiency of bacterial biosurfactant for biocontrol of Rhizoctonia solani (AG - 4) causing root rot in faba bean (Vicia faba) plants

2018 ◽  
Vol 153 (4) ◽  
pp. 1237-1257 ◽  
Author(s):  
Samia Ageeb Akladious ◽  
Eman Zakaria Gomaa ◽  
Omima Mohammed El-Mahdy
Keyword(s):  
Rhizoctonia Solani ◽  
Vicia Faba ◽  
Faba Bean ◽  
Root Rot

scholarly journals First Report of Box Blight Caused by Cylindrocladium pseudonaviculatum (C. buxicola) in British Columbia, Canada

Plant Disease ◽  
2013 ◽  
Vol 97 (4) ◽  
pp. 559-559 ◽  
Author(s):  
J. F. Elmhirst ◽  
B. E. Auxier ◽  
L. A. Wegener
Keyword(s):  
British Columbia ◽  
Room Temperature ◽  
Its Region ◽  
Host Tissue ◽  
Green Mountain ◽  
Single Spore ◽  
Black Water ◽  
Leaf Spots ◽  
Buxus Sempervirens ◽  
Fraser Valley

Boxwoods (Buxus spp.) are common woody ornamental hedging plants in Europe and North America, typically propagated by cuttings. In October 2011, shoot dieback and defoliation was observed on Buxus sempervirens ‘Suffruticosa’ (dwarf English boxwood) and ‘Green Balloon’ in outdoor, 10-cm pots at a wholesale nursery in Chilliwack, British Columbia. Circular leaf spots with black rings occurred on leaves and black, water-soaked, cankers girdled the stems and petioles. Leaf and stem samples were collected on November 21, 2011, and incubated for 48 h in a moist chamber at room temperature. In addition to Volutella buxi, a Cylindrocladium species producing conidia on white sporodochia was observed on host tissue under the microscope. Leaves with lesions were surface-sterilized in 10% bleach for 30 to 60 s, rinsed in sterile water, and lesions were cut out and plated on PDA and carnation leaf media. The species was identified as Cylindrocladium pseudonaviculatum Crous, J.Z. Groenew. & C.F. Hill 2002 by comparison of conidia and phialide morphology to published descriptions. Conidia were hyaline, one-septate, cylindrical with rounded ends and 38 to 76 μm (mean 51 μm) × 4 to 6 μm on carnation leaf media and 41 to 66 μm (mean 52 μm) × 4 to 6 μm on B. sempervirens ‘Suffruticosa’ leaves, comparable to the reported range of 40 to 75 × 4 to 6 μm (1,2,3,4). Conidia were produced in clusters on terminal, ellipsoid vesicles at the tips of penicillate conidiophores. Vesicles were 10.2 (7.6 to 12.8 μm) at the widest point, consistent with the 6 to 11 μm reported in (2,3) and tapered to a rounded point; stipe extensions were septate and measured an average of 130 μm (107 to 163 μm) in length to the tip of the vesicle, consistent with the 95 to 155 μm reported in (1), 89 to 170 μm reported in (2), and 95 to 165 μm in (3). Chlamydospores were not observed on host tissue but appeared in older PDA cultures as dark brown microsclerotia. DNA was extracted from single-spore colonies on PDA and the internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS1 and ITS4. The ITS sequence (GenBank Accession No. KC291613) was 100% identical to C. buxicola strain CB-KR001 (HM749646.1) and Calonectria pseudonaviculata strain ATCC MYA-4891 (JX174050.1). In early December 2011, box blight was identified on container-grown B. sinica var. insularis × B. sempervirens ‘Green Velvet,’ ‘Green Gem’, and ‘Green Mountain’ and B. sempervirens L. (common or American boxwood). The pathogen was identified by microscopic examination at three wholesale nurseries in the eastern Fraser Valley and one landscape planting. The isolate has been deposited in the Canadian Collection of Fungal Cultures in Ottawa, Canada (DAOM 242242). References: (1) B. Henricot and A. Culham. Mycologia 94:980, 2002. (2) K. L. Ivors, et al. Plant Dis. 96:1070, 2012. (3) C. Pintos Varela, et al. Plant Dis. 93:670, 2009. (4) M. Saracchi, et al. J. Plant Pathol. 90:581, 2008.

scholarly journals Temperature, Moisture, and Seed Treatment Effects on Rhizoctonia solani Root Rot of Soybean

Plant Disease ◽  
2003 ◽  
Vol 87 (5) ◽  
pp. 533-538 ◽  
Author(s):  
A. E. Dorrance ◽  
M. D. Kleinhenz ◽  
S. A. McClure ◽  
N. T. Tuttle
Keyword(s):  
Soil Moisture ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
Seed Treatment ◽  
Anastomosis Group ◽  
Control Measures ◽  
Root Weight ◽  
Wide Range ◽  
Plant Stand ◽  
Growth Chamber Studies

The effects of temperature and soil moisture on infection and disease development by Rhizoctonia solani on soybean were studied individually. In addition, the anastomosis group of R. solani isolates recovered from soybean from 35 fields in 15 counties was determined. All of the 44 isolates recovered in this study were AG-2-2 IIIB. Five isolates of R. solani were able to infect and colonize soybean roots and hypocotyls at 20, 24, 28, and 32°C in growth chamber studies. The temperatures evaluated in this study were not limiting to the isolates tested. In greenhouse studies, nine R. solani isolates and a noninoculated control were evaluated at 25, 50, 75, and 100% soil moisture holding capacity (MHC). Root weights were greater and percent stand averages higher at 50 and 75% than at 25 or 100% MHC; however, as percentage of control, the main effect on percent moisture for percent stand, plant height, or root weight was not significant. There were significant differences among the isolates for the percent stand, root rot rating, and root fresh weight of soybean in each study. In both temperature and moisture studies, the R. solani isolates could be separated as predominantly causing (i) seed rot, as detected by greatly reduced plant stand; (ii) root rot generally having no effect on plant stand but a high root rot rating and low root weight; or (iii) hypocotyl lesions, having no effect on plant stand, a low root rot score, and a high number of red lesions on the hypocotyl. In the greenhouse seed treatment evaluations of five fungicides, there was no fungicide by isolate interaction using these pathogenic types of R. solani. None of the seed treatments evaluated in this study provided 100% control of the four isolates tested. Due to the wide range of environmental factors that permit R. solani infection and disease on soybeans, other control measures that last all season, such as host resistance, should be emphasized.

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