Incidence and Severity of Crown and Root Rots on Four Apple Rootstocks Following Exposure to Phytophthora Species and Waterlogging

Plants of four apple (Malus ×domestica Borkh.) rootstock clones, M.7, M.26, MM.111, and Ottawa (O.) 3, were grown in unamended potting medium or in the same medium infested with Phytophthora cactorum (Leb. & Cohn) Schroet., P. cambivora (Petri) Buisman, P. cryptogea Pethyb. & Laff., or P. megasperma Drechsler, causal agents of crown and root rots. Plants were flooded for either 0, 24, 48, or 72 h every 7 days for 4 months, then assessed for disease incidence and severity. Averaged across all pathogens and rootstocks, mean crown rot incidences were 2.5%, 6.3%, 19%, and 50% following weekly flooding periods of 0, 24, 48, and 72 h, respectively; when averaged across all rootstocks and flooding treatments, mean incidences of crown rot caused by P. cryptogea, P. cactorum, P. cambivora, and P. megasperma were 36%, 26%, 15%, and 8.8%, respectively; when averaged across all four pathogens, mean crown rot incidences after 72 h of flooding were 40%, 45%, 50%, and 75% for M.26, 0.3, M.7, and MM.111, respectively. In contrast, 72-h flooding periods in the absence of a pathogen were least detrimental to growth of MM.111 clones and most detrimental to shoot growth of M-26. Exceptions to general trends were reflected by statistical interactions among pathogens, rootstocks, and flooding durations, e.g., after 72-h floodings, 0.3 was the rootstock with the greatest amount of root rot caused by P. cryptogea but the least amount caused by P. megasperma. Differential disease susceptibility among rootstocks appeared greatest with respect to P. cactorum and least with respect to P. cryptogea.

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Phytophthora Species Associated with Crown and Root Rot of Apple in Chile

Plant Disease ◽

10.1094/pdis.2001.85.6.603 ◽

2001 ◽

Vol 85 (6) ◽

pp. 603-606 ◽

Cited By ~ 6

Author(s):

B. A. Latorre ◽

M. E. Rioja ◽

W. F. Wilcox

Keyword(s):

Central Valley ◽

Phytophthora Species ◽

Crown Rot ◽

Apple Rootstocks ◽

Apple Trees ◽

Potting Medium ◽

Root And Crown Rot ◽

Genotype Interaction ◽

Crown And Root Rot ◽

Isolated Species

Phytophthora cactorum, P. cryptogea, P. gonapodyides, and P. megasperma were isolated from necrotic root and crown tissues or the rhizospheres of apple trees exhibiting typical symptoms of Phytophthora root and crown rot in the Central Valley of Chile. Representative isolates of all four species were pathogenic on a variety of apple rootstocks and scions in trials conducted on excised shoots and 1-year-old MM.106 rootstock grown for 4 months in infested potting medium. P. cactorum was the most frequently isolated species and the most virulent in pot tests, although a significant Phytophthora sp.-apple genotype interaction was observed. This is the first report of any species other than P. cactorum causing root and crown rot of apple trees in Chile.

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Resistance to Phytophthora Species among Rootstocks for Cultivated Prunus Species

HortScience ◽

10.21273/hortsci10391-17 ◽

2017 ◽

Vol 52 (11) ◽

pp. 1471-1476 ◽

Cited By ~ 2

Author(s):

Gregory T. Browne

Keyword(s):

Root Rot ◽

Phytophthora Species ◽

Crown Rot ◽

Phytophthora Cactorum ◽

Prunus Species ◽

Phytophthora Megasperma ◽

Soil Flooding ◽

Root And Crown Rot ◽

Crown And Root Rot ◽

Multiple Species

Many species of Phytophthora de Bary are important pathogens of cultivated Prunus L. species worldwide, often invading the trees via their rootstocks. In a series of greenhouse trials, resistance to Phytophthora was tested in new and standard rootstocks for cultivated stone fruits, including almond. Successive sets of the rootstocks, propagated as hardwood cuttings or via micropropagation, were transplanted into either noninfested potting soil or potting soil infested with Phytophthora cactorum (Lebert & Cohn) J. Schöt., Phytophthora citricola Sawada, Phytophthora megasperma Drechs, or Phytophthora niederhauserii Z.G. Abad & J.A. Abad. Soil flooding was included in all trials to facilitate pathogen infection. In some trials, soil flooding treatments were varied to examine their effects on the rootstocks in both the absence and presence of Phytophthora. Two to 3 months after transplanting, resistance to the pathogens was assessed based on the severity of root and crown rot. ‘Hansen 536’ was consistently more susceptible than ‘Lovell’, ‘Nemaguard’, ‘Atlas’, ‘Viking’, ‘Citation’, and ‘Marianna 2624’ to root and/or crown rot caused by P. cactorum, P. citricola, and P. megasperma. By contrast, susceptibility to P. niederhauserii was similarly high among all eight tested genotypes of peach, four genotypes of peach × almond, two genotypes of (almond × peach) × peach, and one genotype of plum × almond. Most plum hybrids were highly and consistently resistant to crown rot caused by P. niederhauserii, but only ‘Marianna 2624’ was highly resistant to both crown and root rot caused by all of the Phytophthora species. The results indicate that there is a broad tendency for susceptibility of peach × almond rootstocks and a broad tendency for resistance of plum hybrid rootstocks to multiple species of Phytophthora.

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Identification and characterization of Phytophthora species associated with crown and root rot of pistachio trees in California.

Plant Disease ◽

10.1094/pdis-05-21-1064-re ◽

2021 ◽

Author(s):

Florent Trouillas ◽

Mohamed Taieb Nouri ◽

Tyler Bourret

Keyword(s):

Root Rot ◽

Sequence Data ◽

Strong Support ◽

Phytophthora Species ◽

Crown Rot ◽

Widespread Occurrence ◽

Root Rots ◽

Crown And Root Rot ◽

Pistachio Trees

Pistachio is one of the most widely cultivated nut crops in California with approximately 115,000 hectares of bearing pistachio trees. In recent years, several orchards were identified with declining trees leading to substantial tree losses. Symptoms included trees with poor vigor, yellowing and wilting of leaves, crown rot and profuse gumming on the lower portion of trunks. Thirty-seven Phytophthora-like isolates were obtained from crown rot tissues in the rootstock of grafted pistachio trees and characterized by means of multi-locus phylogeny comprising ITS rDNA, beta-tubulin and mt cox1 sequence data. The analysis provided strong support for the delineation and identification of three Phytophthora species associated with declining pistachio trees, including Phytophthora niederhauserii, P. mediterranea and P. taxon walnut. Pathogenicity studies in potted UCBI rootstocks (clonal and seeded) confirmed that all three Phytophthora species can cause crown and root rot of pistachio, thus fulfilling Koch’s postulates. The widespread occurrence of Phytophthora crown rot in recently planted pistachio orchards and the high susceptibility of UCBI rootstocks suggest this disease constitute an emerging new threat to the pistachio industry of California. To the best of our knowledge, this study is the first to report P. niederhauserii, P. mediterranea and P. taxon walnut as causal agents of crown and root rots of pistachio.

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Relative resistance of newly released apple rootstocks to Phytophthora cactorum

Canadian Journal of Plant Science ◽

10.4141/p04-176 ◽

2006 ◽

Vol 86 (1) ◽

pp. 199-204 ◽

Cited By ~ 6

Author(s):

O. Carisse ◽

S. Khanizadeh

Keyword(s):

Root Rot ◽

Cultural Practices ◽

Integrated Approach ◽

Crown Rot ◽

Lesion Length ◽

Phytophthora Cactorum ◽

High Susceptibility ◽

Apple Rootstocks ◽

Relative Resistance ◽

Moderate Susceptibility

New rootstocks from series SJM (St-Jean-Morden) and SJP84 (ST-Jean-1984) have been evaluated for agronomic qualities since 1970 and 1975, respectively. As a result of the evaluation, seven and nine rootstocks from the SJM and SJP84 series, respectively, were selected. However, these were not evaluated for crown rot resistance. Excised shoot assay was used to evaluate resistance of 22 apple rootstocks to crown rot caused by Phytophthora cactorum (Leb. and Cohn.) Schroet. The pathogenicity of four isolates of P. cactorum to apple rootstocks was confirmed using the same excised twig assay. For both tests, relative lesion length was used as a measure of susceptibility. The analysis of variance showed that there was a significant effect of rootstocks, isolate and the interaction between rootstock and isolate. In general, apple rootstocks were more susceptible to isolate PC04-02 followed by isolates PC04-03 and PC04-01 and less susceptible to isolate PC04-04. The selection SJM189 was the least susceptible to P. cactorum and SJP84-5162 and SJM15 were the most susceptible suggesting that these rootstocks may not be suitable in orchards with favourable conditions to P. cactorum infection. Excised twigs of the SJP84-5180, SJP84-5189, SJP845174, O.3, SJP84-5230, O.3A, SJP84-5198, SJM167 and M.44 showed low to moderate susceptibility, whereas, rootstocks SJP845231, SJM150 and M.26 showed moderate susceptibility to P. cactorum. Rootstocks SJM188, SJP84-5217, MM.111, SJM127, SJP84-5218 and MM.106 showed high susceptibility to P. cactorum. The present results confirmed that none of the released or commercial rootstocks are completely resistant to P. cactorum and an integrated approach including resistance, chemical control and cultural practices is recommended to manage P. cactorum in apple orchards. Key words: Apple breeding, crown rot, Malus domestica Borkh., root rot

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STUDIES OF CROWN ROT OF APPLE TREES

Canadian Journal of Research ◽

10.1139/cjr42c-040 ◽

1942 ◽

Vol 20c (9) ◽

pp. 457-490 ◽

Cited By ~ 25

Author(s):

Maurice F. Welsh

Keyword(s):

Soil Moisture ◽

Apple Tree ◽

Disease Incidence ◽

Antagonistic Effect ◽

Crown Rot ◽

Phytophthora Cactorum ◽

Additional Information ◽

Two Factors ◽

Below Ground ◽

Old Trees

The form of apple tree crown rot that occurs in the irrigated orchards of British Columbia is confined to the below-ground bark tissues of the tree. It has been encountered in trees of all ages and of all the commercial varieties.Proof is given that this crown rot is caused by the fungus Phytophthora cactorum (L. & C.) Schroet. Typical symptoms of the disease have been reproduced in over 200 trees of various ages as a result of their inoculation with this fungus. Isolation has been possible only from the margins of active lesions, and has proved difficult even from these tissues. There is evidence that the activity of P. cactorum is inhibited in rotted tissues by the antagonistic effect of one or more secondary organisms.The influence of soil moisture and temperature on disease incidence has been studied by field observations and by the inoculation of two-year—old trees under controlled conditions in Wisconsin tank equipment in the greenhouse. The effects of these two factors seem to be interrelated, with the highest incidence of disease in an almost saturated soil at the highest temperature imposed, 32 °C. The influence of soil moisture is exerted particularly in the subsoil, rather than in the locus of crown rot attack.Certain varieties of apple have been found to vary in their resistance to crown rot. Deep wounds have proved necessary to allow entry of the fungus into bark tissues.The additional information now available is being utilized in a search for improved means of combating the disease.

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First Report of Root Rot and Twigs Wilting of Olive Trees in Argentina Caused by Phytophthora nicotianae

Plant Disease ◽

10.1094/pdis-93-7-0765b ◽

2009 ◽

Vol 93 (7) ◽

pp. 765-765 ◽

Cited By ~ 7

Author(s):

A. M. Vettraino ◽

G. Lucero ◽

P. Pizzuolo ◽

S. Franceschini ◽

A. Vannini

Keyword(s):

Root Rot ◽

Disease Incidence ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Phytophthora Palmivora ◽

System Control ◽

Olive Trees ◽

Olive Varieties ◽

Lateral Branches ◽

Old Trees

In Argentina, olives (Olea europaea) are planted on approximately 90,000 ha located primarily in the northwest continental regions. During a 2005 survey, root rot was recorded at several olive plantations in Catamarca, La Rioja, and San Juan provinces (3). Aboveground symptoms associated with root rot were twigs wilting with or without chlorosis, defoliation, and death. Symptoms were initiated on lateral branches and sometimes affected the entire crown. Even if young (5-year-old) trees displayed root rot, aerial symptoms may or may not be seen until years later. Disease incidence varied from 3 to 30%. Rotted rootlets were associated mainly with the infection of Phytophthora palmivora Butler and less frequently with another Phytophthora species. Isolates of this species were heterothallic, had a fluffy growth on carrot agar, and arachnoid growth on potato dextrose agar. Chlamydospores approximately 36 μm in diameter were also produced. The species developed prominent, papillate, noncaducous sporangia of different shapes ranging from ellipsoid to spherical when submerged in saline solution. Sporangia were 35 to 57 × 25 to 45 μm (average 44 × 33 μm), L:B ratio from 1.1 to 1.7. Isolates formed oogonia and amphyginous antheridia following mating type assays. On the basis of morphological features, these isolates were identified as P. nicotianae Breda de Haan. Identity was confirmed by sequencing the rDNA internal transcribed spacer (GenBank Accession No. FJ746693) (1). One-year-old O. europea seedlings were challenged with P. nicotianae (A1 isolates 306G and 339) through soil infestation assay in a growth chamber at 25°C. Infested and uninfested autoclaved millet grains moistened with V8 juice were used to inoculate 15 olive seedlings per isolate and controls, respectively. Fifty days after inoculation, seedlings showed foliar symptoms similar to those observed in the field and had an average of 50% reduction in the root system. Control plants remained healthy. P. nicotianae was always reisolated from symptomatic roots. P. nicotianae was reported on Citrus aurantium in Argentina in 1947 and is currently associated with several hosts (2). In 2002, the same species was reported associated with olive root rot in southern Italy (4). It is possible that P. nicotianae was recently introduced into Argentina through importation of Mediterranean olive varieties. The demonstrated pathogenicity of P. nicotianae on olive together with the recently reported detection of P. palmivora (3) presents a serious threat to olive cultivation in Argentina. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) M. J. Frezzi. Rev. Investig. Agric. 4:47, 1950. (3) G. Lucero et al. Plant Pathol. 56:728, 2007. (4) F. Nigro and A. Ippolito. Acta Hortic. 586:777, 2002.

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Annuals and Herbaceous Perennials Tolerant or Resistant to Phytophthora Species in the Landscape1

Journal of Environmental Horticulture ◽

10.24266/0738-2898-38.3.107 ◽

2020 ◽

Vol 38 (3) ◽

pp. 107-113

Author(s):

M. S. Henson ◽

S. R. Sharpe ◽

I. M. Meadows

Keyword(s):

Ipomoea Batatas ◽

Disease Incidence ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Crown Rot ◽

Herbaceous Plant ◽

Susceptible Host ◽

Phytophthora Cryptogea ◽

Herbaceous Perennials ◽

Phytophthora Drechsleri

Abstract Plants of one or two cultivars of 16 annuals and 14 herbaceous perennials were evaluated based on desirability and anecdotal evidence of resistance to Phytophthora root or crown rot. Six plant cultivars served as susceptible controls. Three landscape beds were established in North Carolina and each was infested with three species of Phytophthora: P. nicotianae, P. drechsleri, and P. tropicalis. Plants were regularly rated for disease incidence and symptomatic plants were assayed to determine the presence of Phytophthora species. Ten cultivars of annuals and seven cultivars of herbaceous perennials did not exhibit symptoms of Phytophthora root or crown rot or other disease throughout the season (June 4 to October 15, 2018). Phytophthora spp. were recovered from seven and six cultivars of the evaluated annuals and herbaceous perennials, respectively. Phytophthora nicotianae, P. drechsleri, or P. cryptogea were recovered from a susceptible host in each landscape bed. P. tropicalis was recovered from one plant cultivar evaluated. Phytophthora cryptogea was recovered from three plant cultivars, although this species was not intentionally introduced in the landscape beds. We identified 22 plant cultivars within 13 herbaceous plant species that grew vigorously in landscape beds infested with species of Phytophthora. Index words: bedding plants, disease resistance, herbaceous perennials, landscape plants, Phytophthora nicotianae, Phytophthora drechsleri, Phytophthora tropicalis. Species used in this study: yarrow (Achillea millefolium L. ‘Desert Eve Red'), fernleaf yarrow (Achillea filipendulina Lam. ‘Moonshine Yellow'), angelonia (Angelonia angustifolia Benth. ‘ArchAngel Pink', ‘Serenita White'), annual vinca (Catharanthus roseus (L.) G. Don ‘Cora Apricot', ‘Cora Strawberry', ‘Pacifica Raspberry'), celosia (Celosia argentea L. ‘New Look'), tickseed (Coreopsis auriculata L. ‘Nana', ‘Yellow Jethro Tull'), purple coneflower (Echinacea purpurea (L.) Moench ‘Cheyenne Spirit', ‘PowWow Wild Berry'), blanket flower (Gaillardia x grandiflora Hort. ‘Goblin', ‘Mesa Bi-color'), Barberton daisy (Gerbera jamesonii Bolus ex Hooker f. ‘Crazy Daisy'), verbena (Glandularia canadensis ‘Homestead Purple'), >dusty miller (Jacobaea maritima (L.) Pelser & Meijden ‘Silver Dust'), New Guinea impatiens (Impatienshawkeri W.Bull ‘Hamony', ‘Sunpatiens Compact Orchid', ‘Sunpatiens Lilac'), sweet potato vine (Ipomoea batatas (L.) Lam. ‘Ace of Spades', ‘Bright Idea Tri-color'), West Indian lantana (Lantana camara L. ‘Miss Huff'), lantana (Lantana x hybrida ‘New Gold'), shasta daisy (Leucanthemum x superbum (Bergmans ex J.W. Ingram) Bergmans ex Kent. ‘Becky', ‘Snow Lady'), bee balm (Monarda didyma L. ‘Petite Delight', ‘Jacob Cline'), ornamental grass (Panicum virgatum L. ‘Rotstrahlbusch', ‘Shenandoah'), geranium (Pelargonium x hortorum L.H. Bailey (pro. sp.) ‘Bullseye Cherry', Calliope Dark Red'), calibrachoa (Petunia x calibrachoa ‘Super Cal'), petunia (Petunia x hybrida (Hooker) Vilmorin ‘Easy Wave Red', ‘Easy Wave White', ‘Wave Purple', ‘Yellow Madness', Violet Picotee'), annual phlox (Phlox drummondii Hook. ‘Intensia Red Hot', ‘Phlox Star'), garden phlox (Phlox paniculata L. ‘Amethyst True Gal'), black-eyed susan (Rudbeckia hirta L. ‘Indian Summer', ‘Prairie Sun'), mealy blue sage (Salvia farinacea Benth. ‘Victoria Blue'), African marigold (Tagetes erecta L. ‘Inca Yellow', ‘Proud Yellow'), French marigold (Tagetes patula L. ‘Disco Mix', ‘Disco Yellow'), narrowleaf zinnia (Zinnia angustifolia Kunth. ‘Star Orange', ‘Star White'), Phytophthora nicotianae Breda de Haan, Phytophthora cryptogea Pethybr. and Laff, Phytophthora drechsleri Tucker, Phytophthora tropicalis Aragaki and J.Y. Uchida, zinnia (Zinnia elegans Jacq. ‘Magellan Orange').

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Basal Petiole Rot and Plant Kill of Zamioculcas zamiifolia Caused by Phytophthora nicotianae

Plant Disease ◽

10.1094/pd-90-1107b ◽

2006 ◽

Vol 90 (8) ◽

pp. 1107-1107 ◽

Cited By ~ 1

Author(s):

C. T. Feng ◽

W. C. Ho ◽

Y. C. Chao

Keyword(s):

Morphological Characteristics ◽

Selective Medium ◽

Phytophthora Species ◽

Phytophthora Nicotianae ◽

Peat Moss ◽

Pathogenicity Test ◽

Root Rots ◽

Potting Medium ◽

Pathogenicity Tests ◽

Foliage Plant

Zamioculcas zamiifolia (Lodd.) Engl., commonly called ‘ZZ’ plant, is a monocotyledonous plant in the Araceae. It is a new introduction in the foliage plant industry worldwide and is an increasing popular ornamental foliage plant in Taiwan. In 2003, basal petiole rot and death of ZZ plants were found in two nurseries in southern Taiwan with 18% of the plants diseased at one nursery. Early symptoms were water soaking of the petiole base and a slight yellowing of the leaflets followed by browning of leaflets. As the disease progressed, the petiole base became dark brown, shriveled, collapsed, and eventually rotted. The surface of the roots and rhizomes of diseased plants were initially blackish brown followed by root rots and mortality of plants. A Phytophthora species was consistently isolated from diseased petioles, rhizomes, and roots on a selective medium (4). Two single zoospore isolates (2), each from a different nursery, were used for morphological and pathogenicity tests. The isolates were grown on vegetable juice agar (10% V8 juice, 0.02% CaCO3, and 2% agar [VJA]) at 28°C with 12-h irradiation for 10 days. Sporangia were nondeciduous, terminal or intercalary, and attached to irregularly or sympodially branched sporangiophores. Papillate sporangia were spherical to broadly ovoid or obpyriform, averaged 37.3 × 30.2 μm, and ranged from 23 to 55 μm in length by 17 to 46 μm in diameter, with a length/breadth ratio of 1.24 and a range of 1.1 to 1.4. Chlamydospores with walls 1 to 4 μm thick were terminal or intercalary, spherical, averaged 30.6 μm in diameter, and ranged from 18 to 46 μm. On the basis of the morphological characteristics above, Phytophthora nicotianae Breda de Haar. (synonym P. parasitica Dastur) was identified (1). Paired with known A1 and A2 mating types of P. cinnamomi on VJA, both P. nicotianae cultures were A2, forming oospores after 14 days in darkness at 28°C. Disease-free ZZ plants were propagated by rhizomes in 242-cm3 round pots with 500 g of sterilized potting medium (vermiculite/peat moss/perlite = 1:2:1). Plants with 30 cm long petiole were used for inoculation. For the pathogenicity test, both isolates were grown on VJA plates sealed with Parafilm at 28°C in darkness. After 10 days, aerial mycelia with sporangia were scraped off the plates, placed in 10 ml of sterile distilled water at 8°C for 15 min to release zoospores. A zoospore suspension was adjusted to 104 zoospores/ml following enumeration with a microliter pipette (3) and 200 ml of the suspension was added to each pot, or rhizomes and roots were dipped in 400 ml of the suspension for 60 min and planted immediately. Ten plants were inoculated with either method and water was added to inoculated control plants. Water soaking of the petiole bases developed in 7 days and mortality occurred in 10 days in a screenhouse after plants were inoculated with either method. Control plants remained healthy and no petiole, root, or rhizome rots developed. P. nicotianae was isolated from the advancing lesions of the inoculated plants and both experiments were repeated. To our knowledge, this is the first report of basal petiole rot and plant kill of Zamioculcas zamiifolia caused by P. nicotianae. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) W. C. Ho and W. H. Ko. Bot. Bull. Acad. Sin. 38:41, 1997. (3) W. H. Ko et al. Phytopathology 63:1206, 1973. (4) W. H. Ko et al. Trans. Br. Mycol. Soc. 71:496, 1978.

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Phytophthora mediterranea sp. nov., a New Species Closely Related to Phytophthora cinnamomi from Nursery Plants of Myrtus communis in Italy

Forests ◽

10.3390/f12060682 ◽

2021 ◽

Vol 12 (6) ◽

pp. 682

Author(s):

Carlo Bregant ◽

Antonio A. Mulas ◽

Giovanni Rossetto ◽

Antonio Deidda ◽

Lucia Maddau ◽

...

Keyword(s):

New Species ◽

Root Rot ◽

Phytophthora Cinnamomi ◽

Colony Growth ◽

Phytophthora Species ◽

Maximum Temperature ◽

Pathogenicity Test ◽

Forest Nurseries ◽

Collar And Root Rot ◽

A New Species

Monitoring surveys of Phytophthora related diseases in four forest nurseries in Italy revealed the occurrence of fourteen Phytophthora species to be associated with collar and root rot on fourteen plants typical of Mediterranean and alpine regions. In addition, a multilocus phylogeny analysis based on nuclear ITS and ß-tubulin and mitochondrial cox1 sequences, as well as micromorphological features, supported the description of a new species belonging to the phylogenetic clade 7c, Phytophthora mediterranea sp. nov. Phytophthora mediterranea was shown to be associated with collar and root rot symptoms on myrtle seedlings. Phylogenetically, P. mediterranea is closely related to P. cinnamomi but the two species differ in 87 nucleotides in the three studied DNA regions. Morphologically P. mediterranea can be easily distinguished from P. cinnamomi on the basis of its smaller sporangia, colony growth pattern and higher optimum and maximum temperature values. Data from the pathogenicity test showed that P. mediterranea has the potential to threaten the native Mediterranean maquis vegetation. Finally, the discovery of P. cinnamomi in alpine nurseries, confirms the progressive expansion of this species towards cold environments, probably driven by climate change.

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Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans

BioControl ◽

10.1007/s10526-021-10083-w ◽

2021 ◽

Author(s):

Mudassir Iqbal ◽

Maha Jamshaid ◽

Muhammad Awais Zahid ◽

Erik Andreasson ◽

Ramesh R. Vetukuri ◽

...

Keyword(s):

Root Rot ◽

Fungal Pathogens ◽

Aureobasidium Pullulans ◽

Grey Mould ◽

Lesion Size ◽

Plant Diseases ◽

Crown Rot ◽

Whole Plants

AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.

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