scholarly journals First Report of Rhizoctonia solani AG-7 on Cotton in Mississippi

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1156-1156
Author(s):  
R. Baird ◽  
W. Batson ◽  
D. Carling ◽  
M. Scruggs
Keyword(s):  
Plant Growth ◽  
Gossypium Hirsutum ◽  
Rhizoctonia Solani ◽  
Field Study ◽  
Potato Dextrose Agar ◽  
Distilled Water ◽  
Gossypium Hirsutum L ◽  
First Report ◽  
Secondary Roots ◽  
Isolate Identification

During a field study of the soilborne mycobiota on cotton (Gossypium hirsutum L.) roots, Rhizoctonia solani Kühn AG-7 was isolated from dark brown lesions present on the tap, feeder, and secondary roots onto potato-dextrose agar (PDA) (34 g of medium per liter of distilled water). Isolate identification was confirmed using tester R. solani AG-7 isolates (Carling, University of Alaska) for comparison during anastomosis pairing. To confirm pathogenicity, six AG-7 isolates (65, 66, 67, 68, 69, 70) obtained from cotton roots were tested in a plant growth incubator (18–24°C) by mixing 2.5 ml of 2-week-old cornmeal sand inoculum (3 g cornmeal, 100 g sand, and 20 ml distilled water) with 500 ml of autoclaved soil into each of five replicate polystyrene pots (15 cm wide × 20 cm long) per isolate. Five control pots containing noninfested soil were added for comparison. Five seed of cv. Deltapine 50 were sown into each pot. For all six isolates, mean stand counts (ranging from 0 and 1.3 plants per pot) were significantly lower (P ≤ 0.05) compared with those of plants in noninfested pots (3.8 plants per pot) at 21 days after planting. Furthermore, when the roots of surviving seedlings were evaluated for disease severity, brown, discolored lesions were observed at the base of stems and on roots in infested pots for all six isolates. Six AG-7 cultures of the pathogen were reisolated from symptomatic tissues onto PDA. The experiment was repeated with similar results. This is the first report of AG-7 occurring in Mississippi.

scholarly journals First Report of Macrophomina phaseolina on Cotton (Gossypium hirsutum) in Georgia

Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 487-487 ◽  
Author(s):  
R. E. Baird ◽  
J. H. Brock
Keyword(s):  
Gossypium Hirsutum ◽  
Field Study ◽  
Production System ◽  
Macrophomina Phaseolina ◽  
Potato Dextrose Agar ◽  
Distilled Water ◽  
Gossypium Hirsutum L ◽  
First Report ◽  
Cotton Seeds ◽  
Secondary Roots

In a field study evaluating the diversity and density of the soilborne mycobiota in a cotton (Gossypium hirsutum L.) production system, Macrophomina phaseolina (Tassi) Goidanich was isolated on potato dextrose agar from dark brown to black lesions on feeder and secondary roots. Multiple proliferations of feeder and secondary roots were also observed. Isolate RB 656 obtained from these lesions was tested for pathogenicity in the greenhouse by mixing 25 ml of 2-week-old cornmeal sand inoculum (3 g of cornmeal, 100 g of sand, and 20 ml of distilled water) with 5 liters of autoclaved soil (Leefield loamy sand, pH 6.2) per pot (40 × 200 cm). Control pots containing autoclaved soil alone were included for comparison. On 17 September, 10 cotton seeds of DPL 90 were sown per pot. Each treatment had five replications. Forty days after planting, plant heights from pots containing M. phaseolina were lower (14.8 cm) than those in the control pots (19.6 cm), but stand counts were similiar. On this date, four plants were left in each pot to allow the remaining seedlings to reach full maturity. On 9 December, the four plants per replicate pot were removed and roots evaluated for damage. Lesions similiar to those seen originally were observed on the secondary and feeder roots of the infested pots, and the characteristic proliferation of feeder and secondary roots was noted. Tap roots in pots containing M. phaseolina were smaller (11.6 cm) than in the control pots (18.6 cm). Isolate RB 656 was reisolated from the damaged roots in the treated pots. This is the first report of M. phaseolina on cotton in Georgia.

scholarly journals First Report of Rhizoctonia solani AG-7 in Georgia

Plant Disease ◽  
1997 ◽  
Vol 81 (7) ◽  
pp. 832-832 ◽  
Author(s):  
R. E. Baird ◽  
D. E. Carling
Keyword(s):  
Gossypium Hirsutum ◽  
Rhizoctonia Solani ◽  
Pathogenic Fungi ◽  
Anastomosis Group ◽  
Loamy Sand ◽  
Distilled Water ◽  
Sterile Soil ◽  
Gossypium Hirsutum L ◽  
First Report

During a study to determine the pathogenic fungi overwintering on dead cotton (Gossypium hirsutum L.) roots, two isolates of Rhizoctonia solani Kühn anastomosis group 7 (AG-7) were identified. Isolate #213 was obtained from dead roots near Tifton, GA, and isolate #219 was cultured from cotton roots near Midville, GA. Rhizoctonia solani AG-7 was previously reported in Arkansas, Indiana, and Asia (1). Isolates #213 and #219 were tested in the greenhouse for pathogenicity by mixing 25 ml of 2-week-old cornmeal sand inoculum (3 g of cornmeal, 100 g of sand, and 20 ml of distilled water) into 20 × 100 cm pots containing 2.25 liters of sterile soil (Tifton loamy sand, pH 6.1) per pot. Pots with noninfested soil were included as a control. Eight seeds of cotton (Delta and Pineland 90 DPL 90) were sown per pot. Each pot was a replicate and each treatment was replicated five times. At 20 days after planting, plant stands in soil infested with isolate #213 or #219 averaged 2 to 3 or 4 to 5 plants per pot, respectively, while stands in noninfested soil averaged 7 to 8 plants per pot. Brownish colored, sunken lesions were observed on roots, hypocotyles, and cotyledons of plants from pots infested with R. solani AG-7. Isolates #213 and #219 were reisolated from plants grown in their respective treatments. This is the first report of R. solani AG-7 in Georgia. Reference: (1) R. E. Baird et al. Plant Dis. 80:1421, 1996.

Effect of plant growth regulators and defoliants on growth and productivity of american cotton (Gossypium hirsutum L.)

2021 ◽  
Vol 58 (4) ◽  
pp. 650-656
Author(s):  
Sukhwinder Kaur ◽  
Kulvir Singh ◽  
J S Deol ◽  
Sudeep Malik ◽  
Navjyot Kaur
Keyword(s):  
Plant Growth ◽  
Gossypium Hirsutum ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Gossypium Hirsutum L

scholarly journals First Report of the Pathogenicity of Rhizoctonia solani on Salvinia molesta and S. minima in Florida

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 813-813
Author(s):  
M. B. Rayachhetry ◽  
T. R. Center ◽  
T. D. Center ◽  
P. Tipping ◽  
P. D. Pratt ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Native Species ◽  
Tap Water ◽  
Tween 80 ◽  
Fluorescent Light ◽  
Distilled Water ◽  
Salvinia Molesta ◽  
Potato Dextrose Broth ◽  
First Report ◽  
Mycelial Suspension

Salvinia molesta Mitchell (giant salvinia) and S. minima Baker (common salvinia) are exotic aquatic ferns that have invaded drainage basins in Texas, Louisiana, Alabama, Arizona, California, Florida, Georgia, Hawaii, Mississippi, North Carolina, and Oklahoma (2). These ferns rapidly colonize bodies of water and form thick mats, displace native species, disrupt recreational activities like boating and fishing, block drainage and irrigation intakes, interfere with electricity generation, and degrade water quality (1). Patches of water-soaked lesions were observed on the pinnules and rachises of screenhouse-grown S. molesta plants in Florida. Mycelia spread centrifugally from these patches and caused diseased plants to disintegrate and sink. Brown-to-black sclerotia were formed on and around the disintegrated plants. A fungus was consistently isolated from symptomatic tissues of S. molesta plants. Seven-day-old cultures turned buff-colored and produced sclerotia on potato dextrose agar, while cultures on water agar were hyaline and produced black sclerotia. Both types of sclerotia were not differentiated into rind and medulla. The mycelia branched at right angles from the main hyphae, were constricted at the base of the angle, and had a septum after the constriction. Vegetative cells were multinucleate. The fungus was identified as Rhizoctonia solani Kühn (3,4). Koch's postulates were performed to confirm pathogenicity on S. molesta and S. minima. Seven-day-old cultures of R. solani that were grown in potato dextrose broth were filtered through four layers of cheesecloth and washed with distilled water. Fourteen grams of the mycelial residue was suspended in 28 ml of distilled water and macerated in a small blender for 30 s to obtain a mycelial suspension. Healthy S. molesta and S. minima plants grown in screenhouse-tanks were immersed in tap water supplemented with 1 drop per 4 liters of surfactant (Tween 80), rinsed thoroughly, and approximately 40 g of the plants was floated in plastic jars (18.5 cm diameter × 7.5 cm high) filled to a depth of 5 cm with tap water. Three jars each of S. molesta and S. minima were misted with 1.5 ml of the mycelial suspension. Individual jars were covered with a clear plastic lid with a 2.5-cm-diameter hole in the center for ventilation. These jars were placed in a growth chamber maintained at 28 (+1)°C and 12-h fluorescent light cycles. Typical water-soaked lesions appeared on pinnules within 3 to 7 days, spread rapidly, and resulted in disintegration of pinnules and rachises. R. solani was consistently reisolated from symptomatic tissues of both Salvinia species. To our knowledge, this is the first report confirming pathogenicity of R. solani on S. molesta and S. minima. This fungus should be further evaluated as a potential mycoherbicide for control of Salvinia species. References: (1) K. L. S. Harley and D. S. Mitchell. J. Aust. Inst. Agric. Sci. 47:67, 1981. (2) C. C. Jacono et al. Castanea 66:214, 2001. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1991. (4) C. C. Tu and J. W. Kimbrough. Bot. Gaz. 139:454, 1978.

scholarly journals First Report of Target Spot of Flue-cured Tobacco Caused by Rhizoctonia solani AG-3 in China

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1824-1824 ◽  
Author(s):  
Y.-H. Wu ◽  
Y.-Q. Zhao ◽  
Y. Fu ◽  
X.-X. Zhao ◽  
J.-G. Chen
Keyword(s):  
Rhizoctonia Solani ◽  
Morphological Characteristics ◽  
Liaoning Province ◽  
Universal Primers ◽  
Its2 Region ◽  
Distilled Water ◽  
Leaf Section ◽  
Tobacco Leaves ◽  
First Report ◽  
Target Spot

In early August 2006, a disease caused severe losses in a 1,400-ha field of 5-month-old tobacco plants in Kuandian and Fengcheng Counties, Dandong City of Liaoning in northeast China. Symptoms were observed on almost every plant. Disease symptoms were subsequently observed at nearly 100% incidence in 2,000 ha of fields from three towns in Kaiyuan County and two towns in Xifeng County, Tieling City, Liaoning Province in the second half of August 2006. Symptoms first appeared on leaves as small (2 mm) water soaked spots, and developed into expanded, dark brown lesions (2 cm) on the middle to lower leaves. Each lesion exhibited concentric rings, a necrotic center, and a tear in the center and margin that often resulted in a shot-hole appearance. Fungal isolates were obtained from the margins of lesions that were surface-sterilized by dipping each leaf section into 75% ethyl alcohol for 3 sec, then in 0.1% HgCl2 for 15 sec, rinsing in sterilized distilled water three times, and plating the leaf section onto half-strength potato dextrose agar (PDA). Six isolates were identified as Rhizoctonia solani Kühn on the basis of mycelial characteristics: multinucleate cells, septate hyphae constricted at the junction of hyphae, and hyphal branching at approximately right angles (3). The sequence of the internal transcribed spacer (ITS) 1-5.8S-ITS2 region of rDNA from each of six isolates was amplified by PCR assay using universal primers ITS1 and ITS4. The sequences (GenBank Accession Nos. JQ219152 to JQ219157) matched 100% with the ITS sequence of an isolate of R. solani AG-3 (GQ885147). Koch's postulates were conducted for each of the six isolates by wound-inoculating six tobacco leaves (cv. NC89) detached from a total of three 8-week-old plants. Each tobacco leaf was first surface-sterilized in 0.5% NaOCl for 30 sec, rinsed in sterilized distilled water, and wounded at each of four locations by inserting a needle into the leaf. Each leaf was inoculated by depositing a PDA plug (0.5 cm diameter) colonized with R. solani onto each of the four wounds; wounded control leaves (six tobacco leaves from a total of three plants) were inoculated similarly with non-colonized PDA plugs. Inoculated leaves were incubated at 28°C in natural light within a plastic container covered with a hyaline cap to maintain high relative humidity. Symptoms similar to those observed on the original plants developed on inoculated leaves within 3 days, but not on the control leaves. The pathogen was reisolated from symptomatic leaves but not from control leaves and showed morphological characteristics consistent with those of R. solani. Tobacco target spot has been recorded in South America (1), South Africa (4), Argentina, and the USA (2). However, to our knowledge, this is the first report of target spot caused by R. solani AG-3 on flue-cured tobacco in China. References: (2) J. S. Johnk et al. Phytopathology 83:854, 1993. (4) H. D. Shew et al. Plant Dis. 69:901, 1985. (1) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1991. (3) E. Vargas. Turrialba 23:357, 1973.

scholarly journals First Report of Septoria Blight of Parsley Caused by Septoria petroselini in the Mediterranean Region of Turkey

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 99-99 ◽  
Author(s):  
S. Kurt
Keyword(s):  
Mediterranean Region ◽  
Morphological Characteristics ◽  
Potato Dextrose Agar ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Sterile Water ◽  
First Report ◽  
Foliar Symptoms ◽  
Polyethylene Bags ◽  
The Mediterranean

During December 2001 to March 2002, Septoria blight of parsley was observed in approximately 500 ha of commercial parsley crops in Arsuz County, Hatay, in the Mediterranean Region of Turkey. Incidence of disease ranged from 42 to 80%. Symptoms included irregularly shaped, grayish brown spots (average 3 to 8 mm diameter) with a slightly darker brown margin of necrotic tissue that developed into tan-to-brown lesions surrounded by chlorotic halo on the leaves. Oval-shaped lesions were observed occasionally on petioles. Lesions contained erumpent, dark brown, flask-shaped pycnidia with the ostiole on the upper surface of the foliage. Thirty samples, consisting of diseased leaves and petioles of parsley, were collected from each field. Infected tissues were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterile distilled water, placed on petri dishes containing potato dextrose agar (PDA), and incubated for 10 to 14 days at 25°C. The fungus formed long, multiseptate (0 to 4), hyaline, filiform conidia (14 to 29 μm × 0.5 to 1.9 μm), and short conidiophores within the pycnidia. Based on the morphological characteristics of the fungus, the pathogen was identified as Septoria petroselini Desm. (1). Monoconidial cultures of 18 isolates were prepared. Pathogenicity was confirmed by brush-inoculating slightly wounded foliage of 5- to 7- week-old parsley plants (cv. Kereviz yapragi) with a conidial suspension (106 conidia per ml of sterile water) of each isolate of S. petroselini. Control plants that were brush-inoculated with distilled water and inoculated plants were placed in clear polyethylene bags that were closed and incubated at 20°C for 48 h. The bags were removed, and plants were maintained in a dew chamber for 21 days at 65 to 70% relative humidity. Foliar symptoms developed 15 days after inoculation and appeared similar to lesions observed in the field. Yellowing and necrosis of leaves was also observed on >60% of inoculated plants. No lesions developed on the control plants. The pathogen was readily reisolated on PDA from inoculated plants. To our knowledge, this is the first report of Septoria blight of parsley in the Mediterranean Region of Turkey. Reference: (1) R. F. Cerkauskas and J. Uyenaka. Plant Dis. 74:1037, 1990.

scholarly journals Microdrops: A method for inoculation with Rhizoctonia solani Kühn for evaluation of bean (Phaseolus vulgaris L.) genotypes

1969 ◽  
Vol 80 (3) ◽  
pp. 111-122
Author(s):  
Thania A. Polanco ◽  
Rocío del P. Rodríguez ◽  
James S. Beaver
Keyword(s):  
Rhizoctonia Solani ◽  
Petri Dish ◽  
Lesion Size ◽  
Potato Dextrose Agar ◽  
Fungal Mycelium ◽  
Symptom Expression ◽  
Distilled Water ◽  
Phaseolus Vulgaris L ◽  
Validation Tests ◽  
Effect Of Age

Three methods, namely, bulk, microdrops, and 0.5-cm discs of potato dextrose agar (PDA) with fungal mycelium, were evaluated in order to identify a suitable methodology to inoculate bean with Rhizoctonia solani. In the microdrop method, the combination of dilution and volume of inoculum was examined.The effect of age of inoculum and of the leaf on symptom expression was also tested. All inoculations were done on the upper side of the leaf. The best method for symptom expression was the combination of 10 µl with dilutions of 100 ml of sterilized distilled water per Petri dish (60-mm diam).The bulk and disc methods induced severe symptoms causing defoliation 72 h after the inoculation. Four-day-old colonies as source of inoculum were best for symptom expression. With older colonies, lesion size was smaller and the induction of symptoms less successful. Age of trifoliate did not influence the success of the inoculations. Validation tests showed the potential of microdrops as a useful technique for the evaluation of bean genotypes.

Resistance to Rhizoctonia solani and Pythium ultimum in Upland Cotton (Gossypium hirsutum L.)

Crop Science ◽  
2016 ◽  
Vol 56 (4) ◽  
pp. 1784-1791
Author(s):  
Whitney M. Jones ◽  
C. Wayne Smith ◽  
James L. Starr
Keyword(s):  
Gossypium Hirsutum ◽  
Rhizoctonia Solani ◽  
Upland Cotton ◽  
Pythium Ultimum ◽  
Gossypium Hirsutum L
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