scholarly journals Root Rot and Stunting of Hydroponically Grown Endive, Fennel, and Sorrel Caused by Pythium F-group in South Africa

Plant Disease ◽  
2003 ◽  
Vol 87 (7) ◽  
pp. 875-875 ◽  
Author(s):  
N. Labuschagne ◽  
C. Gull ◽  
F. C. Wehner ◽  
W. J. Botha
Keyword(s):  
South Africa ◽  
Root Rot ◽  
Selective Medium ◽  
Vegetable Crops ◽  
Root Tips ◽  
Foeniculum Vulgare ◽  
Hydroponic System ◽  
Stunted Growth ◽  
Root Segments ◽  
Hydroponically Grown

Specialized vegetable crops such as endive (Cichorium endiva), fennel (Foeniculum vulgare), and sorrel (Rumex spp.) are being cultivated hydroponically in South Africa to be marketed as admixtures in salads. Stunted growth accompanied by browning and rotting of the root tips has been observed at a commercial recirculating gravel bed hydroponic system near Pretoria during the warm summer months. Root segments excised from symptomatic plants were rinsed in sterile water and plated on Pythium selective medium (1). Pythium F-group, characterized by the production of noninflated filamentous sporangia and no oospores (2), was isolated from 40% of endive, 60% of fennel, and 7% of sorrel root segments. Koch's postulates were confirmed by inoculating 4-week-old seedlings of each crop in the greenhouse with a Pythium F-group isolate from the particular crop. Inoculations were performed by adding 3 ml of suspension (105 zoospores per ml) to each liter of aerated nutrient solution. Control plants received no inoculum, and the experiment was repeated once. After 4 weeks, inoculated plants showed stunting of the foliage and slight to moderate root rot. Pythium F-group could readily be reisolated from roots of inoculated plants. To our knowledge, this is the first report of Pythium F-group on these crops in South Africa. References: (1) W. J. Botha and R. L. J. Coetzer. S. Afr. J. Bot. 62:196, 1996. (2) M. W. Dick. Keys to Pythium. University of Reading Press, Reading, UK, 1990.

scholarly journals Pythium spp. Infecting Hydroponically Grown Lettuce in South Africa

Plant Disease ◽  
2002 ◽  
Vol 86 (10) ◽  
pp. 1175-1175 ◽  
Author(s):  
N. Labuschagne ◽  
C. Gull ◽  
F. C. Wehner ◽  
W. J. Botha
Keyword(s):  
South Africa ◽  
Nutrient Solution ◽  
Root Rot ◽  
Species Group ◽  
Selective Medium ◽  
Plant Weight ◽  
Stunted Growth ◽  
Hydroponic Systems ◽  
Shoot Weight ◽  
Hydroponically Grown

Root rot and wilting of lettuce (Lactuca sativa L. var. capitata L.) commonly occur in hydroponic systems in South Africa. Plants showing stunted growth, wilt, and root rot were collected at two commercial hydroponic systems in Gauteng Province, and root segments were plated on a Pythium selective medium (1). P. irregulare and three species groups without oogonia (F, HS, and T) were identified (2). Pythium groups F, HS, and T, and P. irregulare were represented by 63, 6, 5, and 26% of the isolates, repectively. Koch's postulates were confirmed in two greenhouse experiments by inoculating 4-week-old lettuce cv. Lutetia seedlings grown in aerated nutrient solution at 21°C. Two V8 juice agar cultures of an isolate of each species or species group were blended in 500 ml of sterile water, and 166 ml of suspension was added to the nutrient solution in each of three 5-liter receptacles containing four lettuce seedlings. Control plants received sterile V8 juice agar suspension. After 4 weeks, all Pythium isolates caused root rot and reduced fresh plant weight significantly, although no wilting occurred. Symptoms were more severe with P. irregulare and Pythium group HS than with groups F and T. Compared to the control, P. irregulare reduced fresh root and shoot weight of plants by 51 and 38%, Pythium group HS by 41 and 33%, Pythium group T by 29 and 26%, and Pythium group F by 30 and 24%, respectively. References: (1) W. J. Botha and R. L. J. Coetzer. S. Afr. J. Bot. 62:196, 1996. (2) M. W. Dick. Keys to Pythium. University of Reading Press, Reading UK, 1990.

scholarly journals Report of Root Rot Caused by Pythium F-Group on Hydroponically Grown Celery in South Africa

Plant Disease ◽  
2002 ◽  
Vol 86 (4) ◽  
pp. 441-441
Author(s):  
N. Labuchagne ◽  
C. Gull ◽  
F. C. Wehner ◽  
W. J. Botha
Keyword(s):  
South Africa ◽  
Nutrient Solution ◽  
Root Rot ◽  
Apium Graveolens ◽  
Gauteng Province ◽  
Warm Summer ◽  
Hydroponic Systems ◽  
Hydroponically Grown ◽  
Zoospore Suspension ◽  
Group 1

Celery (Apium graveolens) is commonly grown in hydroponic systems in South Africa. During the warm summer months, plants often become stunted or die, with mortality as high as 70% in some systems. Affected plants show severe root rot and yellowing of the foliage. Root segments excised from symptomatic celery plants collected from various hydroponic systems in Gauteng Province, South Africa, were rinsed in sterile distilled water and plated on PARP medium (2). Pythium was isolated consistently from both rotted and symptomless roots. Isolates produced only noninflated filamentous sporangia and no oospores, conforming to the description of Pythium F-group (1). Koch's postulates were confirmed by inoculating 4-week-old celery seedlings cultivated in aerated nutrient solution in a hydroculture system in the greenhouse. A zoospore suspension (105 zoospores per ml) of Pythium F-group cultured on V8 juice agar was added to the nutrient solution at the rate of 3 ml/1iter. Control plants received no inoculum, and the experiment was repeated once. Plants were assessed after 4 weeks. All inoculated plants showed symptoms of root rot, stunting, and yellowing, whereas control plants remained healthy. Pythium F-group was recovered on PARP medium only from the roots of inoculated plants. Pythium F-group has been described as a pathogen of celery elsewhere, but to our knowledge, this is the first report of root rot caused by the fungus on celery in South Africa. References: (1) M. W. Dick. Keys to Pythium. University of Reading Press, Reading, UK, 1990. (2) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986.

scholarly journals Spraying hydroponic lettuce roots with a suspension concentrate formulation of Bacillus velezensis to suppress root rot disease and promote plant growth

2014 ◽  
Vol 67 ◽  
pp. 213-219 ◽  
Author(s):  
M. Kanjanamaneesathian ◽  
R. Wiwattanapatapee ◽  
W. Rotniam ◽  
W. Wongpetkhiew
Keyword(s):  
Lactuca Sativa ◽  
Root Rot ◽  
Bacterial Cells ◽  
Bacillus Velezensis ◽  
Root Tips ◽  
Hydroponic System ◽  
Root Rot Disease ◽  
Promote Plant Growth ◽  
Shoot Weight ◽  
Rot Disease

Bacillus velezensis was prepared as a suspension concentrate (SC) and sprayed on to the roots of 1monthold Lactuca sativa grown in a hydroponic system In the first experiment using Lactuca sativa (var Red Coral) with root rot symptoms a 1 blank with no cells a 1 SC (1013 CFU/ml) and 1 fresh bacterial cells (FC) (1014 CFU/ml) reduced the percentage of root tips colonized by the pathogen and increased the fresh shoot weight compared to plants that were not sprayed In the second experiment with L sativa (var Green Oak) using healthylooking roots a 1 blank 10 SC (1013 CFU/ml) and 1 FC of the bacterium (1014 CFU/ml) reduced the percentage of root tips colonized by Pythium sp The SC and FC of the bacterium increased the fresh shoot weight while the blank the SC and the FC of the bacterium increased the dried weight of the shoot

Microbiology of Hydroponically-Grown Lettuce

1984 ◽  
Vol 47 (10) ◽  
pp. 765-769 ◽  
Author(s):  
EVE C. RISER ◽  
JOSEPH GRABOWSKI ◽  
EDWARD P. GLENN
Keyword(s):  
Health Concern ◽  
Aerobic Bacteria ◽  
Vegetable Crops ◽  
Enterobacter Agglomerans ◽  
Salmonella Spp ◽  
Hydroponic System ◽  
Lactuca Sativa L ◽  
Modal Values ◽  
Hydroponically Grown

The microbial quality of lettuce (Lactuca sativa L. var. “Ostinata”) cultivated in a hydroponic system was evaluated. Over a 3-month study period, samples of lettuce, nutrient solution, and peat-vermiculite growing mixture from the greenhouse were analyzed for total aerobic bacteria, yeasts, molds, and coliforms. There was a consistent amount of each type of organism occurring within each sample group for a given month, and the numbers of aerobic bacteria and coliforms present were generally similar to those reported for lettuce and leafy vegetable crops propagated by the conventional method of agriculture. Over the study period, the modal values for each type of organism in lettuce were: aerobic bacteria, 7.9 × 106 CFU/g (range of 3.8 × 104 to 2.3 × 108); coliforms, 1.5 × 104 CFU/g (range of none detected to greater than or equal to 5.3 × 107); molds, 2.9 × 103 CFU/g (range of 1.2 × 102 to 5.3 × 104); and yeasts, 2.4 × 104 CFU/g (range of 6.9 × 102 to 2.3 × 106). The primary organisms associated with the growing system were Citrobacter freundii, Enterobacter cloacae, and Enterobacter agglomerans. No organisms of human health concern (i.e. Salmonella spp., Clostrium botulinum, Escherichia coli, or Staphylococcus aureus) were detected in the samples. The bacteriology of lettuce produced for market by this type of hydroponic farming and packaging appears to be generally comparable to that of field-grown lettuce and to present no unique microbiological hazards to consumers.

Calonectria scoparia. [Descriptions of Fungi and Bacteria].

1993 ◽  
Author(s):  
P. W. Crous
Keyword(s):  
South Africa ◽  
Pisum Sativum ◽  
Geographical Distribution ◽  
Root Rot ◽  
Persea Americana ◽  
Damping Off ◽  
Araucaria Heterophylla ◽  
Splash Dispersal ◽  
Shoot Blight ◽  
Stem Cankers

Abstract A description is provided for Calonectria scoparia. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Acacia spp. (68, 1566), Araucaria heterophylla, Eucalyptus spp., Fragaria sp., Luma sp., Medicago sativa, M. truncatula, Persea americana, Pinus spp., Pisum sativum, Rhododendron spp., Prunus sp., Syncarpia gummifera. DISEASE: Damping off, root rot, cutting rot, stem cankers, leaf spotting, seedling and shoot blight. GEOGRAPHICAL DISTRIBUTION: Australia, Brazil, India, Kenya, Mauritius, South Africa. TRANSMISSION: Wind and splash dispersal.

Xylophilus ampelinus. [Descriptions of Fungi and Bacteria].

1991 ◽  
Author(s):  
J. F. Bradbury
Keyword(s):  
South Africa ◽  
Geographical Distribution ◽  
Bacterial Blight ◽  
Early Spring ◽  
Distribution Map ◽  
Stunted Growth ◽  
Leaf Spots ◽  
Overhead Irrigation ◽  
Sources Of Infection ◽  
Xylophilus Ampelinus

Abstract A description is provided for Xylophilus ampelinus. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOST: Vitis vinifera. DISEASE: Bacterial blight of the grapevine; 'Tsilik marasi' in Greece; 'Maladie d'Oleron' in France; 'Mel nero' in Italy; 'Vlamsiekte' in South Africa. In early spring buds on infected spurs fail to open or make stunted growth which eventually dies. Affected spurs often appear slightly swollen because of hyperplasia of the cambial tissue. Cracks appear along such spurs and enlarge to form cankers. Young shoots may develop pale yellowish-green spots on the lowest internodes. These expand upwards on the shoot, darken, crack and develop into cankers. Cracks and later cankers also form on more woody branches later in spring. In summer, cankers are often seen on the sides of petioles causing a characteristic one-sided necrosis of the leaf. They may also appear on main and secondary flower and fruit stalks. Leaf spots and marginal necrosis sometimes occur. Gum formation is not necessarily a symptom. GEOGRAPHICAL DISTRIBUTION: South Africa, France, Greece (including Crete), Italy (including Sardinia and Sicily), Spain, Turkey (68, 367). (IMI Distribution Map 531, ed 2, 1986). TRANSMISSION: Bacteria are carried by moisture to wounds, leaf scars and other sites where infection may take place. Primary infection can take place without wounding. Grafting and pruning can cause much spread of the disease. Overhead irrigation contributes to spread and development (51, 551). Observations indicate that sources of infection survive in vines even after removal of visibly infected parts.

Identification of the causal agent of Armillaria root rot of Pinus species in South Africa

Mycologia ◽  
2000 ◽  
Vol 92 (4) ◽  
pp. 777-785 ◽  
Author(s):  
Martin P. A. Coetzee ◽  
Brenda D. Wingfield ◽  
Teresa A. Coutinho ◽  
Michael J. Wingfield
Keyword(s):  
South Africa ◽  
Root Rot ◽  
Causal Agent ◽  
Pinus Species ◽  
Armillaria Root Rot

scholarly journals Development of a Simple Hydroponic Assay to Study Vertical and Horizontal Resistance of Soybean and Pathotypes of Phytophthora sojae

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 114-123 ◽  
Author(s):  
A. Lebreton ◽  
C. Labbé ◽  
M. De Ronne ◽  
A. G. Xue ◽  
G. Marchand ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Root Rot ◽  
Dry Weight ◽  
Phytophthora Sojae ◽  
Horizontal Resistance ◽  
Phytophthora Root Rot ◽  
Hydroponic System ◽  
Long Term Stability ◽  
Vertical Resistance

Phytophthora root rot, caused by Phytophthora sojae, is one of the most damaging diseases of soybean and the introgression of Rps (Resistance to P. sojae) genes into elite soybean lines is arguably the best way to manage this disease. Current bioassays to phenotype the gene-for-gene relationship are hampered with respect to reproducibility and long-term stability of isolates, and do not accurately predict horizontal resistance individually. The aim of our study was to investigate a new way of phenotyping P. sojae isolates and vertical and horizontal resistance in soybean that relies on zoospores inoculated directly into a hydroponic system. Inoculation of P. sojae isolates against a set of eight differentials accurately and reproducibly identified pathotypes over a period of two years. When applied to test vertical resistance of soybean lines with known and unknown Rps genes, the bioassay relied on plant dry weight to correctly identify all genes. In addition, simultaneous inoculations of three P. sojae isolates, collectively carrying eight major virulence factors against 64 soybean lines with known and unknown levels of horizontal resistance, separated the plants into five distinct groups of root rot, allowing the discrimination of lines with various degrees of partial resistance. Based on those results, this bioassay offers several advantages in facilitating efforts in breeding soybean for P. sojae resistance and in identifying virulence factors in P. sojae.

scholarly journals Interactive effect of AM fungi with Trichoderma viride and Pseudomonas fluorescens on growth and yield of broccoli

2013 ◽  
Vol 49 (No. 3) ◽  
pp. 137-145 ◽  
Author(s):  
A. Tanwar ◽  
A. Aggarwal ◽  
S. Kaushish ◽  
S. Chauhan
Keyword(s):  
Pseudomonas Fluorescens ◽  
Glomus Intraradices ◽  
Interactive Effect ◽  
Trichoderma Viride ◽  
Am Fungi ◽  
Dry Weight ◽  
Growth And Yield ◽  
Vegetable Crops ◽  
Fresh Weight ◽  
Root Tips

Most of the vegetable crops are known to depend upon arbuscular mycorrhizal fungal (AM) symbiosis for growth and development, since AM fungi provide nutrients and water in exchange for photosynthates.  The influences of AM fungi (Glomus intraradices (G) and Acaulospora laevis (A)) with Trichoderma viride (T) and Pseudomonas fluorescens (P) alone and in combinations on growth, mycorrhization, chlorophyll content, nutrient uptakes, and yield of broccoli plants were studied in pot culture under glasshouse conditions. The obtained results demonstrated that the single inoculation of broccoli plants with T. viride significantly increased the above ground fresh weight, root length, chlorophyll b, head diameter, root phosphorus, and shoot nitrogen in comparison to uninoculated control plants. On the other hand, consortium of G+A+T+P significantly increased plant height, above ground dry weight, root fresh weight, chlorophyll a, head fresh weight, and root nitrogen content. Similarly, G+T showed maximum leaf area, and P alone showed maximum uptake of shoot phosphorus. Whereas when P was supplied along with T, early flowering was recorded. AM fungal colonisation was negligible and only root tips were found infected in G or A treated plants which confirms low dependency of broccoli on AM fungi.  

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