scholarly journals First Report of Fusarium oxysporum on Sweet Pepper Seedlings in Almería, Spain

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1435-1435 ◽  
Author(s):  
T. Lomas-Cano ◽  
D. Palmero-Llamas ◽  
M. de Cara ◽  
C. García-Rodríguez ◽  
A. Boix-Ruiz ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Molecular Identification ◽  
Citrullus Lanatus ◽  
Fusarium Species ◽  
Phytophthora Capsici ◽  
Petri Dish ◽  
Sweet Pepper ◽  
Crown Rot ◽  
Conidial Suspension ◽  
Pepper Plants

In March of 2013, new symptoms were observed in more than seven million nursery-grown sweet pepper (Capsicum annuum) plants in El Ejido, Almería (southern Spain). Symptoms included wilting without yellowing of leaves and stunting of plants. Plant crowns exhibited necrosis that advanced through the main root along with slight root rot. Xylem was not affected above or below the crown. Symptoms were thought to be caused by the well-known pepper pathogen Phytophthora capsici. However, sporodochia of Fusarium oxysporum were observed on plant crowns. Symptomatic seedlings (n = 200) were sampled and analyzed. Tissue from roots and epidermal crowns were plated on PDA, PARP, and Komada media, as well as stem discs on PDA and Komada. No Phytophthora sp. were observed and F. oxyporum was exclusively isolated from all 200 samples, from roots and crowns, but not from xylem. Pathogenicity of 60 of these F. oxysporum isolates was studied by inoculation onto sweet pepper plants (cv. del Piquillo) at the 2-true-leaf stage. Twelve plants per isolate, grown on autoclaved vermiculite, were inoculated by drenching with 20 ml of a conidial suspension (1 × 105 CFU/ml) of each isolate per plant. Each suspension was obtained by blending one PDA petri dish fully covered with one isolate. Non-inoculated plants served as control. Plants were maintained for 30 days in a growth chamber with a 14-h photoperiod (1.6 ×·104 lux) and temperatures at 23 to 26°C. The assay was conducted twice. Symptoms described above were reproduced on crown and roots of the inoculated plants with no symptoms in stem discs. No symptoms were observed on controls after 48 days. Host specificity was tested for 13 isolates to tomato (Solanum lycopersicum) cv. San Pedro, eggplant (S. melongena) cv. Alegria, cucumber (Cucumis sativus) cv. Marketmore, watermelon (Citrullus lanatus) cv. Sugar Baby, and Chinese cabbage (Brassica campestris subsp. condensa) cv. Kasumi (4). These plants were inoculated as previously described for pathogenicity tests (12 plants per species, repeated twice). None of the plants exhibited the characteristic symptoms after 60 days. Five isolates of F. oxysporum f. sp. radicis-cucumerinum and four isolates of F. o. f. sp radicis-lycopersici were also inoculated without any symptoms in any of the inoculated sweet pepper plants. Morphological identity of all isolates corresponded to F. oxysporum. The fungi were identified following the morphological keys and methodology provided by (1) and (2). Three isolates from the 60 tested were selected for molecular identification. Molecular identification was performed by sequencing partial TEF-1α gene (3). Subsequent database searches by BLASTn indicated that the resulting sequence of 659-bp had 100% identity with the corresponding gene sequence of F. oxysporum. The sequences were identical for the three isolates and were deposited on the EMBL Sequence Database (HG916993, HG916994, and HG916995). Results suggest that the pathogenic ability of the isolates varies from a vascular Fusarium wilt. F. oxysporum f. sp. capsici is a reported pathogen to sweet pepper (5), but the symptoms we have found are closer to those manifested by the formae speciales that causes root and crown rot of other plants. Consistent with the convention stablished for similar diseases we propose the name F. oxysporum f. sp. radicis-capsici f. sp. nov. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (2) P. E. Nelson et al. Fusarium species. An Ilustrated Manual for Identification. The Penn St. University Press, 1983. (3) K. O'Donnell et al. Proc. Nat. Acad. Sci. 95:2044, 1998.(4) L. M. Oelke and P. W. Bosland. Capsicum Eggplant Newsl. 20:86, 2001. (5) V. C. Rivelli. M.S. Thesis. Dep. Plant Pathol. and Crop Phys. Louisiana State Univ., Baton Rouge, 1989.

scholarly journals First Report on Ovate-leaf Atractylodes Damping-off Caused by Fusarium oxysporum species Complex in South Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Oliul Hassan ◽  
Taehyun Chang
Keyword(s):  
South Korea ◽  
Fusarium Oxysporum ◽  
Species Complex ◽  
Disease Incidence ◽  
Fusarium Species ◽  
Morphological Characteristics ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Damping Off ◽  
First Report

In South Korea, ovate-leaf atractylodes (OLA) (Atractylodes ovata) is cultivated for herbal medicine. During May to June 2019, a disease with damping off symptoms on OLA seedlings were observed at three farmer fields in Mungyeong, South Korea. Disease incidence was estimated as approximately 20% based on calculating the proportion of symptomatic seedlings in three randomly selected fields. Six randomly selected seedlings (two from each field) showing damping off symptoms were collected. Small pieces (1 cm2) were cut from infected roots, surface-sterilized (1 minute in 0.5% sodium hypochlorite), rinsed twice with sterile water, air-dried and then plated on potato dextrose agar (PDA, Difco, and Becton Dickinson). Hyphal tips were excised and transferred to fresh PDA. Six morphologically similar isolates were obtained from six samples. Seven-day-old colonies, incubated at 25 °C in the dark on PDA, were whitish with light purple mycelia on the upper side and white with light purple at the center on the reverse side. Macroconidia were 3–5 septate, curved, both ends were pointed, and were 19.8–36.62 × 3.3–4.7 µm (n= 30). Microconidia were cylindrical or ellipsoid and 5.5–11.6 × 2.5–3.8 µm (n=30). Chlamydospores were globose and 9.6 –16.3 × 9.4 – 15.0 µm (n=30). The morphological characteristics of present isolates were comparable with that of Fusarium species (Maryani et al. 2019). Genomic DNA was extracted from 4 days old cultures of each isolate of SRRM 4.2, SRRH3, and SRRH5, EF-1α and rpb2 region were amplified using EF792 + EF829, and RPB2-5f2 + RPB2-7cr primer sets, respectively (Carbone and Kohn, 1999; O'Donnell et al. 2010) and sequenced (GenBank accession number: LC569791- LC569793 and LC600806- LC600808). BLAST query against Fusarium loci sampled and multilocus sequence typing database revealed that 99–100% identity to corresponding sequences of the F. oxysporum species complex (strain NRRL 28395 and 26379). Maximum likelihood phylogenetic analysis with MEGA v. 6.0 using the concatenated sequencing data for EF-1α and rpb2 showed that the isolates belonged to F. oxysporum species complex. Each three healthy seedlings with similar sized (big flower sabju) were grown for 20 days in a plastic pot containing autoclaved peat soil was used for pathogenicity tests. Conidial suspensions (106 conidia mL−1) of 20 days old colonies per isolate (two isolates) were prepared in sterile water. Three pots per strain were inoculated either by pouring 50 ml of the conidial suspension or by the same quantity of sterile distilled water as control. After inoculation, all pots were incubated at 25 °C with a 16-hour light/8-hour dark cycle in a growth chamber. This experiment repeated twice. Inoculated seedlings were watered twice a week. Approximately 60% of the inoculated seedlings per strain wilted after 15 days of inoculation and control seedlings remained asymptomatic. Fusarium oxysporum was successfully isolated from infected seedling and identified based on morphology and EF-1α sequences data to confirm Koch’s postulates. Fusarium oxysporum is responsible for damping-off of many plant species, including larch, tomato, melon, bean, banana, cotton, chickpea, and Arabidopsis thaliana (Fourie et al. 2011; Hassan et al.2019). To the best of our knowledge, this is the first report on damping-off of ovate-leaf atractylodes caused by F. oxysporum in South Korea. This finding provides a basis for studying the epidemic and management of the disease.

scholarly journals Effect of Phosphite on Tomato and Pepper Plants and on Susceptibility of Pepper to Phytophthora Root and Crown Rot in Hydroponic Culture

Plant Disease ◽  
1998 ◽  
Vol 82 (10) ◽  
pp. 1165-1170 ◽  
Author(s):  
H. Förster ◽  
J. E. Adaskaveg ◽  
D. H. Kim ◽  
M. E. Stanghellini
Keyword(s):  
Leaf Area ◽  
Plant Development ◽  
Phosphorus Deficiency ◽  
Phytophthora Capsici ◽  
Hydroponic Culture ◽  
Phosphorus Nutrition ◽  
Crown Rot ◽  
Deficiency Symptoms ◽  
Root And Crown Rot ◽  
Pepper Plants

Tomato and pepper plants were grown hydroponically in a greenhouse using phosphate or technical and commercial formulations of phosphite as sources of phosphorus nutrition to determine the effects on plant development and susceptibility to Phytophthora root and crown rot. Phosphite-treated tomato and pepper plants were deficient of phosphate and developed phosphorus-deficiency symptoms. Growth of plants (leaf area and leaf, stem, and root dry weights) that were fertilized with phosphite was significantly (P < 0.05) reduced compared with phosphate-fertilized plants. In Phytophthora capsici–inoculated pepper plants, incidence of Phytophthora crown rot was significantly reduced in phosphite-treated plants compared with no phosphorus or phosphate-treated plants. Incidence of crown rot in pepper plants treated with 1 mM phosphate plus 0.3 mM phosphite was intermediate between plants treated with only phosphite (1 mM or 0.1 mM) and plants treated with phosphate (1 mM).

scholarly journals First Report of Fusarium Wilt of Strawberry Caused by Fusarium oxysporum in South Carolina

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 911-911 ◽  
Author(s):  
M. Williamson ◽  
D. Fernández-Ortuño ◽  
G. Schnabel
Keyword(s):  
South Carolina ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
The United States ◽  
Crown Rot ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
Clemson University ◽  
First Report

During October 2011, wilted and dead strawberry (Fragaria × ananassa cv. Albion) plants from two commercial fields in South Carolina were sent to the Clemson University Plant Problem Clinic in Pendleton, SC. Symptoms consisted of wilting and chlorosis of foliage, scorch and dieback of older leaves, and stunting of plants. Internal vascular and cortical tissues of plant crowns showed a distinct reddish brown discoloration. To isolate the causal agent, necrotic crown tissue selected from two symptomatic plants from one location and four symptomatic plants from the other were placed on acidified potato dextrose agar (APDA) and on quarter strength acidified PDA (QPDA). Colonies with light purple mycelia and beige or orange reverse colony colors developed on APDA after 5 days of incubation at 25°C. Colonies on QPDA were light purple. Morphology, growth, and development of macroconidia and microconida were consistent with descriptions of Fusarium oxysporum Schlechtend emend. Snyder & Hansen (3). Genomic DNA from 3 isolates (11-1246A, 11-1247A, and 11-1247B) was extracted and purified according to Chi et al. (1). The internal transcribed spacer region comprising ITS1, ITS2, and 5.8S rRNA was amplified by primers ITS1 and ITS4 (4). The sequence comparison revealed a 100% match with F. oxysporum sequences in GenBank. To confirm the pathogenicity of the fungus, roots of 15 strawberry plants (cv. Albion) were cut and then five plants were soaked for 10 min in either 500 ml of conidial suspension (104 conidia/ml) of one of the two isolates or in sterile distilled water. All were then potted in 15-cm pots with artificial peat-based soil mix and maintained at 25°C in the greenhouse. After 6 weeks, all plants inoculated with isolates 1247A and B were stunted and developed wilt symptoms similar to those observed in the field, while the control plants remained healthy. Support roots on all affected plants were soft and flaccid and new feeder roots had brown lesions. Crowns of three plants inoculated with isolate 1247A and four plants inoculated with 1247B showed vascular discoloration. To reisolate, crowns were plated as above and roots were surface sterilized in 10% bleach for 1 min and rinsed in sterile distilled water prior to plating on QPDA. F. oxysporum was isolated at frequencies of 70 and 100% from crowns and 100% from roots of all inoculated plants. To our knowledge, this is the first report of the occurrence of Fusarium wilt caused by F. oxysporum on strawberry plants in South Carolina. The presence of Fusarium wilt in South Carolina should alert growers, county agents, and specialists to properly identify Fusarium wilt symptoms, which may be confused with Anthracnose or Phytophthora crown rot of strawberry. The disease has been reported previously in other countries including the United States (2). References: (1) M. H. Chi et al. Plant Pathol. J. 25:108, 2009. (2) S. T. Koike et al. Plant Dis. 93:1077, 2009. (3) W. C. Snyder and H. N. Hansen. Am. J. Bot. 27:64, 1940. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Application. Academic Press, NY, 1993.

scholarly journals Isolate–Cultivar Interactions, In Vitro Growth, and Fungicide Sensitivity of Fusarium oxysporum Isolates Causing Seedling Disease on Soybean

Plant Disease ◽  
2018 ◽  
Vol 102 (10) ◽  
pp. 1928-1937 ◽  
Author(s):  
D. R. Cruz Jimenez ◽  
M. L. Ellis ◽  
G. P. Munkvold ◽  
L. F. S. Leandro
Keyword(s):  
Fusarium Oxysporum ◽  
Seed Treatment ◽  
Fungal Growth ◽  
Petri Dish ◽  
The United States ◽  
Conidial Suspension ◽  
Phenotypic Characteristics ◽  
Soybean Cultivars ◽  
Cultivar Selection

Fusarium oxysporum is frequently associated with soybean root rot in the United States. Information about pathogenicity and other phenotypic characteristics of F. oxysporum populations is limited. The objective of the research described herein was to assess phenotypic characteristics of F. oxysporum isolates from soybean, including the interaction between isolates and soybean cultivars, fungal growth characteristics in culture, and sensitivity to fungicides commonly used as seed treatment products. The pathogenicity of 14 isolates was evaluated in rolled-towel and Petri-dish assays using 11 soybean cultivars. In the rolled-towel assay, seed were inoculated with a conidial suspension and disease severity was observed. In the Petri-dish assay, F. oxysporum isolates were grown on 2% water agar and seed were placed on the F. oxysporum colony to observe the symptoms that developed. Cultivars differed in susceptibility to F. oxysporum, and significant (P = 0.0140) isolate–cultivar interactions were observed. F. oxysporum isolates differed in radial growth on potato dextrose agar at 25°C. Pyraclostrobin and trifloxystrobin reduced conidial germination with average 50% effective concentration (EC50) of 0.15 and 0.20 µg active ingredient (a.i.)/ml, respectively. Ipconazole reduced fungal growth with average EC50 of 0.23 µg a.i./ml, whereas fludioxonil was ineffective. Our results illustrate soybean F. oxysporum isolate variability and the potential for their management through cultivar selection or seed treatment.

scholarly journals First Report of Crown Rot on Gypsophila (Gypsophila paniculata) Caused by Fusarium proliferatum in Korea

Plant Disease ◽  
2011 ◽  
Vol 95 (2) ◽  
pp. 220-220 ◽  
Author(s):  
H. B. Lee ◽  
C. J. Kim ◽  
H. Y. Mun ◽  
H. S. Choi ◽  
Y. H. Lee ◽  
...  
Keyword(s):  
Fusarium Species ◽  
Its Region ◽  
Plant Diseases ◽  
Crown Rot ◽  
Morphological Data ◽  
Conidial Suspension ◽  
Korean Society ◽  
First Report ◽  
5.8S Rdna ◽  
Causal Fungus

Gypsophilas commonly cultivated are Gypsophila elegans B. and G. paniculata L. In September of 2009 and 2010, a severe wilt symptom due to crown rot was observed on G. paniculata (cv. Bristol Fairy) in greenhouses in Yeosu, South Korea. The area of cultivation (~8 ha) in Yeosu covers 90% of production in the Jeonnam Province. Disease outbreak was 20 to 30% in affected greenhouses. Early symptoms included brown discoloration surrounding basal stems and slight wilting. Late symptoms included a sunken stem rot next to the roots, root rot, severe wilting, and dying plants. The causal fungus appeared to invade plants through the basal stem, causing a crown rot that prevented the plant from taking up water and nutrients. Crown rot occurred on young and mature plants. Ten fungal isolates were recovered from basal stems and roots of wilted plants. Microconidia were abundantly produced on potato dextrose agar (PDA), V8 juice agar (VA), carnation leaf agar (CLA), and oatmeal agar (OA). Microconidia were single celled, variable, oval-ellipsoid cylindrical, straight to curved, club-to-kidney shaped or spindle shaped on OA, more slender on VA. Macroconidia were not found on any media used. Microconidia on PDA were 5.9 to 15.1 (9.9) × 2.7 to 4.3 (3.5) μm. Germinated conidia (or false conidia) were often formed on CLA. Conidiophores as phialides were singly formed but often branched. Length of conidiophores was up to 31.1 μm on CLA. Small-sized chlamydospores were rarely found. Fusarium isolates (EML-GYP1, 2, and 3) were selected and identified. From extracted genomic DNA, the internal transcribed spacer (ITS) region including 5.8S rDNA was amplified using ITS1F (5′-CTTGGTCATTTAGAGGAAGT-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′) primers. Sequence analyses by BLAST indicated that the isolates (GenBank HM560019, HM560020, and HM560021) were most similar to F. proliferatum (EF4534150) with sequence identity values of 99.3, 99.4, and 99.1%, respectively. The causal fungus was determined to be F. proliferatum based on morphological data and ITS rDNA sequences. Pathogenicity tests with the three isolates were performed on 10 plants of G. paniculata using the dipping method. Healthy roots and basal stems were soaked in a conidial suspension adjusted to ~1.2 × 106 conidia/ml (distilled water) for 15 min. Plants were potted in sterile soil, kept in a humid chamber for 72 h, and moved to a greenhouse. The experiment was carried out in duplicate and repeated two times. Similar symptoms to those observed in the greenhouses were seen 7 days after inoculation. The causal fungus was reisolated from the artificially inoculated basal stems, fulfilling Koch's postulates. Control plants whose basal stems and roots were dipped in sterile water showed no crown rot and wilt symptoms. EML-GYP2 was determined to be the most pathogenic. Ten records of disease caused by three Fusarium species (Fusarium sp., F. oxysporum, and F. udum) have been found on gypsophilas (1), but only F. oxysporum has been reported to cause wilt on G. elgans in Korea (2). To our knowledge, this is the first report of crown rot on gypsophila caused by F. proliferatum in Korea as well as the world. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , October 27, 2010, (2) W.-G. Kim and H.-M. Koo. Page 381 in: List of Plant Diseases in Korea. The Korean Society of Plant Pathology, 2009.

scholarly journals Genus Capsicum L. and Diseases of Sweet and Hot Peppers (Review)

2021 ◽  
Vol 7 (10) ◽  
pp. 98-114
Author(s):  
B. Khasanov ◽  
A. Khakimov ◽  
U. Khamiraev ◽  
S. Utaganov ◽  
D. Aznabakieva
Keyword(s):  
Powdery Mildew ◽  
Fusarium Oxysporum ◽  
Parasitic Plants ◽  
Crown Rot ◽  
Root Knot Nematode ◽  
Powdery Mildew Fungus ◽  
Hot Peppers ◽  
Cultivated Species ◽  
Genus Capsicum ◽  
Pepper Plants

This paper reviews taxonomy, importance and diseases of pepper plants belonging to Capsicum genus. Five species of the genus are domesticated, Capsicum annuum being the most cultivated species followed by C. chinense and C. frutescens while C. baccatum and C. pubescens are grown in limited areas of some regions. Review of the available literature data has shown that more than 122 species of microorganisms can cause pepper diseases, including >58 species of fungi, 11 oomycetes, 15 bacteria, 32 viruses, > 6 species of nematodes, and some higher parasitic plants. From these 18 species of fungi, 2 oomycetes, one bacterium, two viruses, one root-knot nematode, two species of each of dodder and broomrape have been recorded in Uzbekistan. However, all of these organisms but one powdery mildew fungus has been registered on other than pepper plants. Previously the authors of the current paper have found that deadly crown rot of both sweet and hot peppers caused by Fusarium oxysporum (supposedly f. sp. radici-capsici) occurred widely in six districts of Uzbekistan.

scholarly journals First Report of Fusarium Wilt Caused by Fusarium oxysporum f. sp. niveum Race 2 in Georgia Watermelons

Plant Disease ◽  
2008 ◽  
Vol 92 (6) ◽  
pp. 983-983 ◽  
Author(s):  
B. D. Bruton ◽  
W. W. Fish ◽  
D. B. Langston
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Fusarium Species ◽  
Block Design ◽  
Genetic Resistance ◽  
Morphological Characteristics ◽  
First Report ◽  
Race 1 ◽  
Race 2

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) is the number one specialty crop grown in Georgia, a state that ranks fourth nationally in watermelon production. In the last 5 years, Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) has been the greatest yield-limiting disease of watermelon in Georgia. In 2004, a seedless-watermelon field of ‘Regency’ and ‘Tri-X 313’ in Berrien County, GA exhibited approximately 40% of wilted plants. Affected plants also exhibited strong discoloration in the crown xylem. Plant samples (cultivars unknown) from a similarly affected field were also tested from Crisp County, GA. Xylem tissue was excised from the main stem of eight diseased plants in the area between the second and third internode, surface sterilized for 1 min in 1% NaOCl, rinsed with 80% ethanol, and plated onto water agar amended with 100 μg/liter of streptomycin sulfate. Fungi with the morphological characteristics of Fusarium oxysporum (4) were consistently recovered from the diseased tissue of all eight plants. The isolates were hyphal tipped and maintained in vials of sterile artificial potting mix until ready for use (1). Isolates were grown on Esposito and Fletcher medium (2) for 10 days, filtered through cheesecloth, and adjusted to 1 × 106 spores/ml. Reference isolates of race 1 and 2 were used as comparisons for race determination of the unknowns. In each of four studies, plants at the two-leaf stage were removed from potting mix, washed gently, and their roots were uniformly trimmed to 2.5 cm. Before repotting, the seedlings were subjected to a 2-min root-dip in the respective spore-containing media. In each study, approximately 40 plants of each watermelon differential were inoculated with the respective isolates. In disease scoring, each plant was considered a rep. ‘Black Diamond’ is susceptible to races 0, 1, and 2; ‘Charleston Gray’ is resistant to race 0; ‘Calhoun Gray’ is resistant to races 0 and 1, and PI-296341-FR (3) is resistant to races 0, 1, and 2 of Fon. Four plants were planted per 15-cm plastic pot, maintained in an air-conditioned headhouse for 24 h, and then placed in the greenhouse in a randomized complete block design. After 30 days, all plants were rated as to healthy, wilted, or dead plants. From eight isolates tested, one isolate from each county was determined to be Fon race 2 on the basis of its ability to wilt/kill a high percentage of the race 1 resistant differential, i.e., ‘Calhoun Gray’. Mean disease percentages for the isolates from each of the two counties on the watermelon differentials were 95 and 100% on ‘Black Diamond’, 68 and 80% on ‘Charleston Gray’, and 70 and 86% on ‘Calhoun Gray.’ Because of apparent genetic drift within our PI-296341-FR population, we determined that these data were not useful for identifying race 2. In fact, we observed a range of 17 to 80% wilt/death in the PI-296341-FR over a total of four studies that included a known race 2 isolate (Calg 13(15); E. Vivoda). To our knowledge, this is the first report of race 2 in Georgia and it increases the number of states to seven in which race 2 has been identified. Five of the top 10 watermelon-producing states have now reported race 2 of Fon for which there is no genetic resistance within commercial cultivars. References: (1) B. D. Bruton et al. Plant Dis. 84:907, 2000. (2) R. Esposito and A. Fletcher. Arch. Biochem. Biophys. 93:369, 1961. (3) R. D. Martyn and D. Netzer. HortScience 26:429, 1991. (4) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, 1983.

scholarly journals Suppression of Phytophthora Root and Crown Rot on Pepper Plants Treated with Acibenzolar-S-Methyl

Plant Disease ◽  
2002 ◽  
Vol 86 (3) ◽  
pp. 292-297 ◽  
Author(s):  
M. E. Matheron ◽  
M. Porchas
Keyword(s):  
Phytophthora Capsici ◽  
Stem Canker ◽  
Crown Rot ◽  
Management Tool ◽  
Disease Development ◽  
Phytophthora Blight ◽  
Chile Pepper ◽  
Bell Tower ◽  
Root And Crown Rot ◽  
Pepper Plants

The fungicide mefenoxam is registered for the control of Phytophthora blight of peppers caused by Phytophthora capsici. Isolates of the pathogen that are insensitive to mefenoxam, however, have been detected in some locations. Consequently, alternative methods are needed to control Phytophthora blight of peppers. Acibenzolar-S-methyl (ABM, Actigard) is a chemical activator of plant disease resistance that has potential for the management of Phytophthora blight of peppers. The effect of foliar applications of ABM on the development of root and crown rot on pepper plants grown in the greenhouse and inoculated with Phytophthora capsici or in soil naturally infested with the pathogen was evaluated. Inhibition of stem canker development on pepper cvs. Bell Tower and AZ9 after four treatments with ABM (75 μg/ml) was significantly greater than on plants receiving a single application of the chemical. Stem canker length on Bell Tower or AZ9 peppers was inhibited by 93.2 to 97.2% and 87.4 to 92.4% when plants were inoculated with P. capsici at 1 or 5 weeks, respectively, after the fourth application of ABM. Survival of chile pepper plants grown in field soil naturally infested with P. capsici was significantly increased by three foliar applications of ABM (75 μg/ml) compared with nontreated plants in all three trials when pots were watered daily and in two of three trials when pots were flooded for 48 h every 2 weeks. When soil was flooded every 2 weeks to establish conditions highly favorable for disease development, plants treated once with mefenoxam (100 μg/ml) survived significantly longer than those treated with ABM. On the other hand, when water was provided daily without periodic flooding to establish conditions less favorable for disease development, plant survival between the two chemicals was not different in two of three trials. Length of survival among chile pepper plants treated twice with 25, 50, or 75 μg/ml of ABM and grown in soil infested with P. capsici was not different. This work indicates that ABM could be an important management tool for Phytophthora root and crown rot on pepper plants.

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