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.

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.

scholarly journals First Report of Crown and Root Rot Caused by Phytophthora capsici on Hydroponically Grown Cucumbers in Norway

Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1138-1138 ◽  
Author(s):  
M. L. Herrero ◽  
M. B. Brurberg ◽  
A. Hermansen
Keyword(s):  
Mating Type ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Yield Reduction ◽  
Cox1 Gene ◽  
Pathogenicity Test ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Leaf Stage ◽  
Root And Crown Rot

In December 2004, symptoms of root and crown rot were observed on cucumbers (Cucumis sativus L.) in a greenhouse in Norway. Cucumbers were the only crop of the greenhouse that used rockwool as a growing substrate in a hydroponical system. The first symptoms were detected in propagation material. One week after planting, symptoms of root and crown rot were observed and approximately 10% of the plants died. Later, losses of 50% in some greenhouses were observed. A yield reduction as much as 65% was estimated in the winter period (January and February). The two main cucumber cultivars planted were Armada and Lopez. In February 2005, Phytophthora capsici (Leonian) (1) was isolated on potato dextrose agar from a sample of cv. Lopez. The isolate produced deciduous, papillate sporangia (occasionally with two or three papilla) and pedicels that were sometimes longer than the sporangia. Sequencing of amplicons of the internal transcribed spacer region (ITS) rDNA and of the mitochondrial cytochrome c oxidase subunit 1 (Cox1) gene (2) confirmed the identification. Three isolates collected through 2005 from the same greenhouse were crossed with tester strains of P. cryptogea. Formation of oogonia and amphigynous antheridia was always observed in crosses with mating type A2; thus, all isolates were the A1 mating type. All three isolates grew well at 35°C and did not produce chlamydospores. A pathogenicity test was performed with one isolate of P. capsici. Four plants of cucumber cvs. Indira and Jessica were grown in a growth chamber at 24°C. Plants at the two-leaf stage were drenched with 20 ml of a zoospore suspension of 106 zoospores per ml per plant. After 18 days, all plants of both cultivars developed symptoms of crown rot or wilted and died. P. capsici was reisolated from inoculated plants of both cultivars. The pathogenicity test was repeated in the same way, but in a greenhouse with temperatures that ranged between 18 and 29°C. In addition, four plants of both cultivars at the four-leaf stage were inoculated with a suspension of 105 zoospores per ml. After 1 week, all plants developed crown rot or were irreversibly wilted, independently of the plant age or the zoospore concentration. To our knowledge, this is the first report of P. capsici in Norway. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society St. Paul MN, 1996. (2) L. P. N. M. Kroon et al. Phytopathology 94:613, 2004.

scholarly journals Phytophthora taxon niederhauserii, a New Root and Crown Rot Pathogen of Banksia spp. in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1216-1216 ◽  
Author(s):  
S. O. Cacciola ◽  
S. Scibetta ◽  
P. Martini ◽  
C. Rizza ◽  
A. Pane
Keyword(s):  
Mating Type ◽  
Saline Solution ◽  
Sandy Loam ◽  
Selective Medium ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Stem Rot ◽  
Infested Soil ◽  
Basal Stem Rot ◽  
Leaf Chlorosis

In the last 10 years, various species of Banksia (family Proteaceae) endemic to Australia have been introduced into Italy where cultivation as flower plants is expanding. In the spring of 2003, a decline associated with root and basal stem rot of 2- to 3-year-old plants of Banksia speciosa R. Br., B. baxteri R. Br., and B. prionotes Lindl. grown in the ground was observed in a commercial nursery in Liguria (northern Italy). Aboveground symptoms included leaf chlorosis and wilt. Plants collapsed within 1 to 2 weeks after the appearance of leaf symptoms. A Phytophthora species was consistently isolated from roots and basal stem on BNPRAH selective medium (3). On V8 juice agar (V8A), axenic cultures obtained by single hyphal transfers formed stellate to radiate colonies with aerial mycelium; on potato dextrose agar (PDA). the colonies showed stoloniform mycelium. Minimum and maximum growth temperatures on PDA and V8A were between 5 and 10°C and 38 and 40°C, respectively, with the optimum at 30°C on PDA (mean radial growth rate of 10 isolates ranged between 9.3 and 10.2 mm per day) and 25 to 30°C on V8A (14 mm per day). In saline solution and soil extract, all isolates produced catenulate hyphal swellings and ellipsoid, nonpapillate, persistent sporangia. Sporangia in saline solution varied from 47 to 70 × 30 to 44 μm (mean l/b ratio of 1.5). All isolates were A1 mating type and produced oogonia with amphyginous antheridia when paired with A2 mating type of P. drechsleri Tucker on V8A plus β-sytosterol (3). The electrophoretic patterns of total mycelial proteins and two isozymes (esterase and malate dehydrogenase) (2) of all isolates from Banksia plants were identical, but distinct from the patterns of isolates of other Phytophthora species, including P. drechsleri, P. megasperma sensu stricto, and P. sojae. Internal transcribed spacer (ITS) regions of rDNA were amplified with primers ITS4/ITS6 and sequences of two isolates, IMI 393960 from B. speciosa and 466/03 from B. baxteri (GenBank Nos. FJ648808 and FJ648809), were 100% identical to sequences of isolates identified as Phytophthora taxon niederhauserii Z. G. Abad and J. A. Abad (GenBank Nos. AY550916, AM942765, and EU244850). Pathogenicity tests were performed on 1-year-old potted plants of B. speciosa with isolates IMI 393960 and 466/03. Twenty plants per each isolate were transplanted into 12-cm-diameter pots containing infested soil prepared by mixing steam-sterilized sandy loam soil with 1% of inoculum produced on autoclaved wheat kernels. Twenty control plants were grown in autoclaved soil mix. Plants were kept in the greenhouse with natural light at 25 ± 2°C and watered to field capacity weekly. All Banksia plants transplanted in infested soil showed symptoms of wilt, leaf chlorosis, and basal stem rot within 2 to 3 weeks. Noninoculated plants remained healthy. P. taxon niederhauserii was reisolated solely from inoculated plants. P. taxon niederhauserii has been reported recently from Banksia spp. in Australia (1), but to our knowledge this is the first report from Italy. P. taxon niederhauserii may represent a threat to the cultivation of many ornamentals including Cystus spp., English ivy, and laurel (4). References: (1) T. I. Burgess et al. Plant Dis. 93:215, 2009. (2) S. O. Cacciola et al. EPPO Bull. 20:47, 1990. (3) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (4) E. Moralejo et al. Plant Pathol, 58:100, 2009.

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 First Report of Neopestalotiopsis clavispora Causing Root and Crown Rot on Strawberry in Italy

Plant Disease ◽  
2019 ◽  
Vol 103 (11) ◽  
pp. 2959-2959 ◽  
Author(s):  
G. Gilardi ◽  
F. Bergeretti ◽  
M. L. Gullino ◽  
A. Garibaldi
Keyword(s):  
Crown Rot ◽  
First Report ◽  
Root And Crown Rot

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 First Report of Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1260-1260 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
D. Minerdi ◽  
M. L. Gullino
Keyword(s):  
Its Region ◽  
The United States ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
Phytophthora Citrophthora ◽  
First Report ◽  
Blastn Analysis ◽  
Root And Crown Rot ◽  
Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

scholarly journals Root and Foot Rot of Lantana Caused by Phytophthora cryptogea

Plant Disease ◽  
2005 ◽  
Vol 89 (8) ◽  
pp. 909-909 ◽  
Author(s):  
S. O. Cacciola ◽  
A. Chimento ◽  
A. Pane ◽  
D. E. L. Cooke ◽  
G. Magnano di San Lio
Keyword(s):  
Sandy Loam ◽  
Heavy Rain ◽  
Early Spring ◽  
Selective Medium ◽  
Plant Diseases ◽  
Infested Soil ◽  
Foot Rot ◽  
American Phytopathological Society ◽  
Electrophoretic Patterns ◽  
Pure Cultures

Lantana (Lantana camara L.) is an evergreen shrub in the Verbenaceae. In some countries, this plant has been declared a noxious weed. However, a number of sterile or near-sterile forms are cultivated as attractive flowered potted and garden plants. In early spring 2004, ≈4,000 potted, small trees of lantana grown in a screenhouse in a commercial nursery of ornamentals near Giarre, Sicily, showed symptoms of chlorosis, defoliation, and sudden collapse of the entire plant. These aboveground symptoms were associated with a reduced root system, rot of feeder roots, and brown discoloration of the base of the stem. A Phytophthora sp. was isolated consistently from roots and basal stems of symptomatic plants using the selective medium of Masago et al. (3). Cardinal temperatures for radial growth of pure cultures obtained by single hypha transfer were 2°C minimum, 25°C optimum, and 30 to 35°C maximum. Sporangia produced in the saline solution of Chen and Zentmyer (3) were obpyriform, persistent, and nonpapillate. All isolates were A1 mating type and differentiated oospores with amphigynous antheridia in dual cultures with A2 reference isolates of P. cryptogea Pethybr. & Laff. and P. drechsleri Tucker (3). Electrophoretic patterns of total mycelial proteins (3) of the isolates from lantana were very similar to those of reference isolates of P. cryptogea from different hosts, but clearly distinct from those of reference isolates of other species included in Waterhouse's taxonomic group VI (3). Indeed, isolates from lantana were identified as P. cryptogea on the basis of morphological and cultural characters as well as the electrophoretic phenotype. Sequences of internal transcribed spacer (ITS) regions of rDNA (1) confirmed the identification as P. cryptogea. Pathogenicity of a representative isolate from lantana (IMI 392045) was tested in a screenhouse by transplanting 20 6-month-old rooted cuttings of lantana in pots (12 cm in diameter) filled with infested soil; the soil was prepared by mixing steam-sterilized sandy loam soil at a concentration of 4% (vol/vol) with inoculum produced on a mixture of vermiculite and autoclaved oat seeds. Twenty control plants were transplanted in pots containing noninfested soil. The soil was saturated with water by plugging the pots' drainage holes for 48 h and watering. After 40 days, all plants except the controls showed symptoms of root and foot rot, and P. cryptogea was reisolated from infected tissues. To our knowledge, this is the first report of P. cryptogea on lantana. On this host and other species in the verbena family, only P. nicotianae van Breda de Haan (= P. parasitica Dastur) has been previously reported (2,3,4). A possible cause of the high incidence of this disease in the nursery was waterlogging due to heavy rain and excessive irrigation. References: (1) S. O. Cacciola et al. For. Snow Landsc. Res. 76:387, 2001. (2) M. L. Daughtrey et al. Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society, St. Paul, MN, 1995. (3) D. C Erwin and O. K. Ribeiro. Pages 39–41, 84–95, 138–139 in: Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (4) K. H. Lamour et al. Plant Dis. 87:854, 2003.

scholarly journals First report of Fusarium commune causing root and crown rot on maize in Italy

Plant Disease ◽  
2021 ◽  
Author(s):  
Monica Mezzalama ◽  
Vladimiro Guarnaccia ◽  
Ilaria Martino ◽  
Giulia Tabome ◽  
Maria Lodovica GULLINO
Keyword(s):  
Plant Disease ◽  
Tap Water ◽  
Morphological Characteristics ◽  
Plant Diseases ◽  
Crown Rot ◽  
Conidial Suspension ◽  
Fusarium Spp ◽  
First Report ◽  
Root And Crown Rot ◽  
Pathogenicity Tests

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 62,587,469 t, with an area that covers 628,801 ha, concentrated in northern Italy (ISTAT 2020). Fusarium species are associated with root and crown rot causing failures in crop establishment under high soil moisture. In 2019 maize seedlings collected in a farm located in San Zenone degli Ezzelini (VI, Italy) showed root and crown rot symptoms with browning of the stem tissues, wilting of the seedling, and collapsing due to the rotting tissues at the base of the stem. The incidence of diseased plants was approximately 15%. Seedlings were cleaned thoroughly from soil residues under tap water. Portions (about 3-5 mm) of tissue from roots and crowns of the diseased plants were cut and surface disinfected with a water solution of NaClO at 0.5% for 2 minutes and rinsed in sterile H20. The tissue fragments were plated on Potato Dextrose Agar (PDA) amended with 50 mg/l of streptomycin sulfate and incubated for 48-72 hours at 25oC. Over the 80 tissue fragments plated, 5% were identified as Fusarium verticillioides, 60% as Fusarium spp., 35% developed saprophytes. Fusarium spp. isolates that showed morphological characteristics not belonging to known pathogenic species on maize were selected and used for further investigation while species belonging to F. oxysporum were discarded. Single conidia of the Fusarium spp. colonies were cultured on PDA and Carnation Leaf Agar (CLA) for pathogenicity tests, morphological and molecular identification. The colonies showed white to pink, abundant, densely floccose to fluffy aerial mycelium. Colony reverse showed light violet pigmentation, in rings on PDA. On CLA the isolates produced slightly curved macronidia with 3 septa 28.1 - 65.5 µm long and 2.8-6.3 µm wide (n=50). Microconidia were cylindrical, aseptate, 4.5 -14.0 µm long and 1.5-3.9 µm wide (n=50). Spherical clamydospores were 8.8 ± 2.5 µm size (n=30), produced singly or in pairs on the mycelium, according to the description by Skovgaard et al. (2003) for F. commune. The identity of two single-conidia strains was confirmed by sequence comparison of the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (O’Donnell et al. 2010). BLASTn searches of GenBank, and Fusarium-ID database, using the partial tef-1α (MW419921, MW419922) and rpb2 (MW419923, MW419924) sequences of representative isolate DB19lug07 and DB19lug20, revealed 99% identity for tef-1α and 100% identity to F. commune NRRL 28387(AF246832, AF250560). Pathogenicity tests were carried out by suspending conidia from a 10-days old culture on PDA in sterile H2O to 5×104 CFU/ml. Fifty seeds were immersed in 50 ml of the conidial suspension of each isolate for 24 hours and in sterile water (Koch et al. 2020). The seeds were drained, dried at room temperature, and sown in trays filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 25°C and RH of 80-85% for 14 days with 12 hours photoperiod. Seedlings were extracted from the substrate, washed under tap water, and observed for the presence of root and crown rots like the symptoms observed on the seedlings collected in the field. Control seedlings were healthy and F. commune was reisolated from the symptomatic ones and identified by resequencing of tef-1α gene. F. commune has been already reported on maize (Xi et al. 2019) and other plant species, like soybean (Ellis et al. 2013), sugarcane (Wang et al. 2018), potato (Osawa et al. 2020), indicating that some attention must be paid in crop rotation and residue management strategies. To our knowledge this is the first report of F. commune as a pathogen of maize in Italy. References Ellis M L et al. 2013. Plant Disease, 97, doi: 10.1094/PDIS-07-12-0644-PDN. ISTAT. 2020. http://dati.istat.it/Index.aspx?QueryId=33702. Accessed December 28, 2020. Koch, E. et al. 2020. Journal of Plant Diseases and Protection. 127, 883–893 doi: 10.1007/s41348-020-00350-w O’Donnell K et al. 2010. J. Clin. Microbiol. 48:3708. https://doi.org/10.1128/JCM.00989-10 Osawa H et al. 2020. Journal of General Plant Pathology, doi.org/10.1007/s10327-020-00969-5. Skovgaard K 2003. Mycologia, 95:4, 630-636, DOI: 10.1080/15572536.2004.11833067. Wang J et al. 2018. Plant Disease, 102, doi/10.1094/PDIS-07-17-1011-PDN Xi K et al. 2019. Plant Disease, 103, doi/10.1094/PDIS-09-18-1674-PDN

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