Phytophthora nicotianae Can Cause Both Crown Rot and Foliage Blight on Phlox paniculata in South Carolina

2014 ◽  
Author(s):  
Daniel T. Drechsler ◽  
Steven N. Jeffers ◽  
William C. Bridges
Keyword(s):  
South Carolina ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Phlox Paniculata ◽  
Foliage Blight

Phytophthora nicotianae Can Cause Both Crown Rot and Foliage Blight on Phlox paniculata in South Carolina

2014 ◽  
Vol 15 (4) ◽  
pp. 159-165
Author(s):  
Daniel T. Drechsler ◽  
Steven N. Jeffers ◽  
William C. Bridges
Keyword(s):  
South Carolina ◽  
Aqueous Suspension ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Experimental Conditions ◽  
Aerial Parts ◽  
Phytophthora Spp ◽  
Potting Medium ◽  
Phlox Paniculata ◽  
Foliage Blight

Phytophthora nicotianae is a common pathogen of many herbaceous perennial plants, and this pathogen has been found causing disease on garden phlox (Phlox paniculata) in wholesale nurseries in South Carolina for a number of years. However, the relationship between P. nicotianae and garden phlox has not been studied or reported previously. Using Koch's postulates and standard inoculation methods for Phytophthora spp., P. nicotianae was found to cause crown rot on P. paniculata when potting medium was infested with colonized vermiculite and to cause foliage blight when aerial parts of the plant were inoculated with an aqueous suspension of zoospores. Foliage blight was more similar to symptoms we observed on garden phlox plants in wholesale nurseries, but crown rot also has been observed previously on plants in these nurseries. The cause of these two diseases was confirmed, but reproduction of Phytophthora foliage blight under experimental conditions was inconsistent. Thus, other factors not yet identified may play a role in the development of Phytophthora foliage blight on garden phlox in nurseries in South Carolina. Accepted for publication 1 September 2014. Published 1 November 2014.

scholarly journals First Report of Phytophthora nicotianae Causing Dianthus chinensis root rot and foliage blight in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Jieying Xu ◽  
Xiao Yang ◽  
Cuiping Wu ◽  
Ziwei Zhou ◽  
Zhenpeng Chen ◽  
...  
Keyword(s):  
Root Rot ◽  
Large Subunit ◽  
Severe Infection ◽  
Average Diameter ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Molecular Evidence ◽  
First Report ◽  
Whole Plant ◽  
Foliage Blight

Dianthus chinensis is a popular ornamental plant that is widely cultivated in China. From May 2020 to 2021, root rot and foliage blight were observed on approximately 50% groundcover plants at several landscape sites of Xuanwuhu Park and Nanjing Railway Station, China. Symptoms of wilting and chlorosis appeared in the initial stage, and severe infection caused the whole plant to die . To recover the causal pathogen, infected root and leaf samples were cut into 5×5 mm2 squares, surface-disinfected in 70% ethanol for 30 sec, placed onto 10% clarified V8 PARP agar at 25°C . After three days, Phytophthora-like hyphae were visibly emerged from both root and leaf tissues and growing into cV8A. Individual hyphal tips were transferred to new cV8A plates to obtain a total of 10 pure isolates. Colony morphology of all isolates on cV8A had slightly radiate to stellate patterns with cottony aerial mycelia. After four or five days all isolates had identical morphological traits including papillate and noncaducous sporangia on cV8, hyphal swellings, and intercalary and terminal chlamydospores. A representative isolate Pni-dc7 was examined for morphological measurements. Sporangia were mostly ovoid and sometimes obpyriform, averaging 28.9±5.6 µm in length and 24.9±5.8 µm in width (n=30). Chlamydospores were abundant and spherical with an average diameter at 29.2 ± 0.3 µm (n=30). Oogonia were not observed. For sequence analysis, the internal transcribed spacer (ITS) regions and large subunit (LSU) of the nuclear ribosomal RNA gene complex were amplified using the primer pairs ITS1/ITS4 and NL1/NL4 , respectively, while the mitochondrial cytochrome c oxidase subunit II (coxII) gene was amplified using FM58/FM66 (Martin et al. 2003). The ITS sequence of isolate Pni-dc7 (GenBank Acc. No. MZ519893) had a 100% identity to those of P. nicotianae (MH219914, KU172524, MT065839). The LSU sequence (MZ573547) had a 100% identity to those of P. nicotianae (KX250514, MZ348950, HQ665198).The cox2 sequence (MZ519893) had a 100% identity to those of P. nicotianae (MH221078, KJ506439, JF707072). Based on morphological and molecular evidence, Pni-dc7 was identified as P. nicotianae. Pathogenicity tests  were conducted using both detached leaves and whole plants. Asymptomatic leaves were collected from healthy plants.A 5×5 mm2 Pni-dc7-colonized cV8A plug was placed on each wound of five leaves. Sterile agar plugs were used for a non-inoculated control leaf. All six leaves were placed on a wet filter paper in a closed container at 25°C. All inoculated leaves had necrotic tissues around the wounds, the symptoms progressed from spots to the entire leaves after two days . The control leaves remained asymptomatic. In the whole-plant assay, a D. chinensis  plant (approx. 0.3 m in height) was inoculated with 5 mL of zoospore suspension that was mixed into the potting soil(500g). Three plants were inoculated and control plants were treated with sterile distilled water. After two weeks all three inoculated plants in three repeats of the assay had root and crown rot and foliage blight, whereas all control plants remained asymptomatic. P. nicotianae was reisolated from all inoculated plants. This is the first report of P. nicotianae causing root rot and foliage blight on D. chinensis in China. Considering the importance of D. chinensis to both ornamental nursery and landscaping industries in China, diseased plants at the landscape sites were removed to prevent the spread of P. nicotianae to production sites and other landscape locations.

Phytophthora nicotianae var. parasitica. [Descriptions of Fungi and Bacteria].

1964 ◽  
Author(s):  
G. M. Waterhouse
Keyword(s):  
Geographical Distribution ◽  
Citrus Fruit ◽  
Heavy Rain ◽  
Drainage Water ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Fruit Rot ◽  
Piper Betle ◽  
Wide Range ◽  
Southern Rhodesia

Abstract A description is provided for Phytophthora nicotianae var. parasitica. 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 comprising 58 families including: avocado, castor, Cinchona spp., citrus, cotton, eggplant, guava, lucerne, papaw, parsley, pineapple, Piper betle, rhubarb, sesame, strawberry, tomato. DISEASES: Damping-off of seedlings (tomato, castor, citrus, cotton); root rot (citrus, avocado, strawberry, lucerne); crown rot (parsley, rhubarb, strawberry, lucerne); brown stem rot of tobacco; stem canker and tip blight of Cinchona spp. ; leaf blight (castor, sesame, pineapple, Piper betle) and fruit rot (citrus, tomato, guava, papaw, eggplant). GEOGRAPHICAL DISTRIBUTION: Africa (Ethiopia, Mali, Madagascar, Mauritius, Morocco, Nigeria, Sierra Leone, Southern Rhodesia, Tanganyika); Asia (Burma, Ceylon, China, Formosa, India, Israel, Japan, Java, Malaya, Philippines); Australia & Oceania (Australia, Hawaii, Tasmania); Europe (Cyprus, France, Germany, Great Britain, Holland, Ireland, Italy, Poland, Portugal, U.S.S.R.); North America (Bermuda, Canada, Mexico, U.S.A.); Central America & West Indies (Costa Rica, Cuba, El Salvador, Guatemala, Jamaica, Montserrat, Puerto Rico, Trinidad);. South America (Argentina, Brazil, British Guiana, Colombia, Paraguay, Peru, Venezuela). TRANSMISSION: Soil-borne, spreading rapidly after heavy rain or where soil remains moist or water-logged (40: 470). Also recorded in drainage water in India and in reservoirs and canals supplying citrus groves in U.S.A. (23: 45; 39: 24). A method for determining a disease potential index in soil using lemon fruit has been described (38: 4). Also present in testas of seeds from diseased citrus fruit which may infect nursery seedbeds (37: 165).

scholarly journals First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Charles Krasnow ◽  
Nancy Rechcigl ◽  
Jennifer Olson ◽  
Linus Schmitz ◽  
Steven N. Jeffers
Keyword(s):  
United States ◽  
South Carolina ◽  
Sequence Similarity ◽  
Morphological Characteristics ◽  
The United States ◽  
Universal Primers ◽  
Broad Host Range ◽  
Pathogenicity Test ◽  
First Report ◽  
Foliage Blight

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old ‘Brandi Burgundy’ chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

scholarly journals First report of Meloidogyne javanica pathogenic on hybrid lavender (Lavandula ×intermedia) in the United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Samara A. Oliveira ◽  
Daniel M. Dlugos ◽  
Paula Agudelo ◽  
Steven N. Jeffers
Keyword(s):  
South Carolina ◽  
Sandy Loam ◽  
Meloidogyne Javanica ◽  
The United States ◽  
Crown Rot ◽  
Cultivated Plants ◽  
Broad Host Range ◽  
First Report ◽  
Tomato Roots ◽  
The Usa

Root-knot nematodes (RKNs), Meloidogyne spp., are some of the most economically important pathogens of cultivated plants. Meloidogyne javanica is one of the most destructive RKN species and is well known for its broad host range and the severe damage it causes to plant roots (Perry et al. 2009). In Feb 2018, four mature dead and dying hybrid lavender plants (Lavandula ×intermedia ‘Phenomenal’) were collected in Edgefield County, South Carolina, and suspected of having Phytophthora root and crown rot (Dlugos and Jeffers 2018). Greenhouse-grown plants had been transplanted in Dec 2016 and Jan 2017 into a sandy loam soil on a site that had been fallow or in pasture for over 30 years. Some plants began to turn gray and die in summer 2017, and approximately 40% of 1230 plants were symptomatic or dead by Feb 2018. Phytophthora spp. were not isolated from the collected plants but were isolated from plants collected on subsequent visits. Instead, all four plants had small, smooth galls on the roots. Lavender roots were examined microscopically (30-70×), and egg masses of RKNs were observed on the galls. Mature, sedentary RKN females were handpicked from galled roots, and perineal patterns of 10 specimens were examined and identified as M. javanica. Juveniles and eggs were extracted from lavender roots by the method of Coolen and D’herde (1972). To confirm species identification, DNA was extracted from 10 individual juveniles, and a PCR assay was conducted using species-specific primers for M. javanica, Fjav/Rjav (Zijlstra et al. 2000). A single amplicon was produced with the expected size of approximately 720 bp, which confirmed identity as M. javanica. To determine pathogenicity, M. javanica from lavender roots were inoculated onto susceptible tomato plants for multiplication, and severe gall symptoms occurred on tomato roots 60 days later. Nematodes were extracted from tomato roots and inoculated onto healthy, rooted cuttings of ‘Phenomenal’ lavender plants growing in pots of soilless medium in a greenhouse. Plants were inoculated with 0, 1000, 2000, 5000, or 10000 eggs and juveniles of M. javanica. Five single-plant replicates were used for each treatment, and plants were randomized on a greenhouse bench. Plants were assessed 60 days after inoculation, and nematodes were extracted from roots and counted. The reproduction factor was 0, 43.8, 40.9, 9.1, 7.7, and 2.6 for initial nematode populations 0, 1000, 2000, 5000, and 10000, respectively, which confirmed pathogenicity (Hussey and Janssen 2002). Meloidogyne javanica also was recovered in Mar 2018 from galled roots on a ‘Munstead’ (L. angustifolia) lavender plant from Kentucky (provided by the Univ. of Kentucky Plant Disease Diagnostic Laboratories), and an unidentified species of Meloidogyne was isolated in Aug 2020 from a ‘Phenomenal’ plant grown in Florida. COI mtDNA sequences from the SC (MZ542457) and KY (MZ542458) populations were submitted to Genbank. M. javanica previously was found associated with field-grown lavender (hybrid and L. angustifolia) in Brazil, but pathogenicity was not studied (Pauletti and Echeverrigaray 2002). To our knowledge, this is the first report of M. javanica pathogenic to L. ×intermedia in the USA, and the first time RKNs have been proven to be pathogenic to Lavandula spp. following Koch’s Postulates. Further studies are needed to investigate the geographic distribution of M. javanica on lavender and the potential threat this nematode poses to lavender production in the USA.

scholarly journals Fusarium Root and Crown Rot: A Disease of Container-Grown Hostas

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 980-988 ◽  
Author(s):  
B. Wang ◽  
S. N. Jeffers
Keyword(s):  
South Carolina ◽  
Crown Rot ◽  
Undescribed Species ◽  
Fresh Weight ◽  
Fusarium Spp ◽  
Disease Symptoms ◽  
Leaf Yellowing ◽  
Oat Seeds ◽  
Root And Crown Rot ◽  
Fusarium Sp

A previously unreported disease was observed on 11 cultivars of container-grown hosta plants at five wholesale nurseries in South Carolina between 1997 and 1999. Symptoms included leaf yellowing, plant stunting, rotting of and vascular discoloration in roots, and necrosis in the crowns. Fusarium spp. consistently were isolated from symptomatic hosta plants. Four species were recovered: F. solani, F. oxysporum, F. proliferatum, and an undescribed species designated Fusarium sp.; F. solani and Fusarium sp. were recovered most frequently. To demonstrate pathogenicity, four methods were used to inoculate hosta plants with representative isolates of F. solani, F. oxysporum, and Fusarium sp. Two types of inoculum, colonized oat seeds and conidium suspensions, were used to inoculate wounded and nonwounded plants. Disease symptoms occurred consistently only on hosta plants inoculated by dipping wounded roots and crowns into suspensions of conidia. Symptoms were most severe on plants inoculated with Fusarium sp. and much less severe on plants inoculated with F. solani or F. oxysporum. Disease severity increased and fresh weight of inoculated plants decreased when the concentration of inoculum of Fusarium sp. was increased over the range of 1 × 103 to 1 × 107 conidia per ml. Isolates of Fusarium sp., F. solani, and F. oxysporum varied in virulence when Hosta ‘Francee’ plants were inoculated. This study demonstrated that Fusarium root and crown rot of container-grown hostas is caused primarily by Fusarium sp. but that it also can be caused by F. solani and F. oxysporum. Fusarium sp. appears to be taxonomically distinct from other species, and its identity currently is under investigation.

scholarly journals Pumpkin Fruit Rot in North Carolina Caused by Phytophthora nicotianae

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 923-923
Author(s):  
G. J. Holmes
Keyword(s):  
Fungal Growth ◽  
Average Diameter ◽  
Soft Rot ◽  
Selective Medium ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Fruit Rot ◽  
Unknown Etiology ◽  
Postharvest Diseases ◽  
Phytophthora Spp

In 1999, during an evaluation of pumpkin (Cucurbita pepo) fruit for susceptibility to naturally occurring postharvest diseases, a soft rot of unknown etiology was noted. No fungal growth or sporulation was seen on the fruit surface and no root or crown rot was observed in the field. When fruit were cross-sectioned, masses of white, floccose mycelium covering large sections of the seed cavity were observed. Rot was observed in 21 fruit (6.4% of the total). The fungus was isolated from symptomatic fruit on a modified P10ARPH agar medium, semi-selective for Phytophthora spp. (2). Isolates from eight fruit formed papillate, ovoid sporangia, abundant chlamydospores, and colonies characteristic of P. nicotianae (1). No oospores were produced. Four sound pumpkin fruit (cv. Early Autumn) were inoculated with four isolates (one isolate per fruit). Each isolate was recovered from a different fruit. Pumpkins were surface sterilized at the point of inoculation by wetting with 70% ethanol. Inoculation was done by removing a small amount of mycelium from pure culture using a sterile, wooden toothpick and inserting it 2 cm deep into opposite sides of the mid section of sound fruit (two inoculations per fruit). Control fruit were punctured with sterile toothpicks (once per fruit). First symptoms appeared 4 days after inoculation at room temperature (22 to 24°C). Symptoms consisted of circular, water-soaked areas originating from the point of inoculation. Average diameter (based on four measurements on two fruit) of the water-soaked lesions were 3 cm at first appearance (i.e., 4 days) and 11 cm 10 days after inoculation. No symptoms developed on controls. When symptomatic fruit were cross-sectioned, masses of white, floccose mycelium were noted. Reisolation of this mycelium onto selective medium yielded P. nicotianae, thus fulfilling Koch's postulates. This is the first report of P. nicotianae causing fruit rot of pumpkins. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (2) H. D. Shew. Phytopathology 77:1090, 1987.

scholarly journals First Report of Phytophthora nicotianae Causing Leaf Blight, Fruit Rot, and Root Rot of Papaya in American Samoa

Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 712-712 ◽  
Author(s):  
P. D. Roberts ◽  
E. Trujillo
Keyword(s):  
Fungal Growth ◽  
Soil Surface ◽  
Pathogenic Fungi ◽  
American Samoa ◽  
Wide Distribution ◽  
Phytophthora Nicotianae ◽  
Crown Rot ◽  
Fruit Rot ◽  
Sterile Water ◽  
Run Off

Papaya trees (Carica papaya) were observed in 1997 with symptoms of acute chlorosis and wilting of foliage, circular whitish lesions with necrotic centers on fruits, and root and trunk rots that killed the diseased trees. Identical symptoms were observed on many trees in fields interplanted with other crops and in home gardens on two of the five islands of American Samoa. A Phytophthora sp. was consistently isolated on water agar from symptomatic stems, fruits, and roots. The fungus was grown in pure culture on V8 juice medium at 25°C under continuous fluorescent illumination, and was identified, on the basis of spherical to broadly ovoid (34 to 67 × 40 to 50 µm), intercalary to terminal sporangia, chlamydospores (20 × 40 µm), and uniform to uneven hyphae (5 to 7 µm wide), as Phytophthora nicotianae Breda de Haan (= P. parasitica Dastur) (1,2). Ten 4-week old papaya seedlings grown on pasteurized soil in 15-cm pots were inoculated with a 2-ml suspension of 100 sporangia per ml in sterile water applied to the soil surface. Six uninoculated plants were used as controls. Two mature fruit that had reached the climacteric point were inoculated with 200 µl of sterile water containing approximately 20 sporangia. Inoculum was placed inside a 1-cm-diameter rubber circle that had been attached to the surface of the fruit to prevent run-off. Two uninoculated fruits served as controls. Inoculations of seedlings and fruit were conducted three times. Wilting symptoms developed on inoculated plants in less than 5 days and plant death accompanied by crown rot occurred in 14 days. Inoculated fruit developed lesions covered with a whitish fungal growth within 10 days after inoculation. Plants and fruits exposed to sterile water were healthy. The pathogen was reisolated from the diseased plants and fruits and it was morphologically identical to the original isolate, confirming its role as the causative agent of the disease. The wide distribution of diseased plants over an estimated one-quarter of the area of the island of Tutuila (approximately 24 sq. km) and on the adjacent island of Ofu indicates that the disease was not of recent introduction. References: (1) H. H. Hob et al. The genus Phytophthora in Taiwan. Inst. Bot., Ac. Sinica, Monogr. Ser. 15., 1995. (2) G. M. Waterhouse and J. M. Waterhouse. C.M.I. Descriptions of Pathogenic Fungi and Bacteria No. 34, 1964.

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