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.

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 Incidence of Phytophthora Blight and Verticillium Wilt Within Chile Pepper Fields in New Mexico

Plant Disease ◽  
2006 ◽  
Vol 90 (3) ◽  
pp. 291-296 ◽  
Author(s):  
S. Sanogo ◽  
J. Carpenter
Keyword(s):  
New Mexico ◽  
Drip Irrigation ◽  
Phytophthora Capsici ◽  
Furrow Irrigation ◽  
Growth Stages ◽  
Phytophthora Blight ◽  
Chile Pepper ◽  
Plant Infection ◽  
Causative Agents ◽  
Pepper Plants

Statewide surveys of commercial chile pepper (Capsicum annuum) fields were conducted in New Mexico from 2002 to 2004 to gain information on the incidence of diseases with wilt symptoms and their causative agents. Fifty-nine fields were surveyed during the course of this 3-year study when chile pepper plants were at growth stages from green fruit to beginning red fruit. All fields were affected by diseases with wilt symptoms. The proportion of total field area exhibiting symptoms of wilt spanned from less than 1% to over 80%. Field diagnostics along with laboratory assays of wilted plants revealed that the wilting was caused by Phytophthora capsici and Verticillium dahliae. The two pathogens were both found in 80% of the fields, and occurred together in some wilted plants in 12% of the fields. Average incidence of plant infection (number of plants infected with P. capsici or V. dahliae out of 5 to 25 wilted plants sampled) varied from approximately 40 to 90% for P. capsici, and from 18 to 65% for V. dahliae. Incidence of plant infection by P. capsici was approximately 40% less in fields with drip irrigation than in fields with furrow irrigation. In contrast, incidence of plant infection by V. dahliae was approximately 32% greater under drip irrigation than under furrow irrigation. In pathogenicity tests, isolates of P. capsici and V. dahliae caused symptoms in inoculated chile pepper identical to those in field-grown chile pepper plants. Results indicate that diseases with wilt symptoms are well established in chile pepper production fields, with P. capsici and V. dahliae posing the most serious challenge to chile pepper producers in New Mexico.

scholarly journals Effectiveness of Nine Different Fungicides for Management of Crown and Root Rot of Chile Pepper Plants Caused by Phytophthora capsici

2015 ◽  
Vol 16 (4) ◽  
pp. 218-222 ◽  
Author(s):  
Michael E. Matheron ◽  
Martin Porchas
Keyword(s):  
Root Rot ◽  
Phytophthora Capsici ◽  
Field Trials ◽  
Pepper Plant ◽  
Plant Mortality ◽  
Phytophthora Blight ◽  
Chile Pepper ◽  
Fungicide Application ◽  
Crown And Root Rot ◽  
Pepper Plants

Bell and chile pepper plants are affected by the economically important disease Phytophthora blight, which is caused by the oomycete pathogen Phytophthora capsici. Greenhouse and field trials were conducted to evaluate and compare the ability of nine different fungicides to reduce development of the crown and root rot phase of Phytophthora blight and the resulting chile pepper plant death when applied at 2- and 4-week intervals. Overall, chile pepper plant mortality was significantly decreased in three greenhouse trials with soil applications of fungicide products containing ametoctradin + dimethomorph, cyazofamid, dimethomorph, ethaboxam, fluazinam, fluopicolide, mandipropamid, mefenoxam, and oxathiapiprolin. The same fungicides, excluding mandipropamid and oxathiapiprolin, also significantly reduced overall plant mortality in two field trials. No significant difference was found between 2- and 4-week fungicide application intervals with respect to chile pepper plant survival in any greenhouse or field trial. In general, the degree of reduction in chile pepper plant mortality was lower in field compared to greenhouse trials, probably due to the respective soil surface spray compared to soil drench method of fungicide application used in each instance. Accepted for publication 17 November 2015. Published 30 November 2015.

scholarly journals Evaluation of Fruit Rot Resistance in Cucurbita Germplasm Resistant to Phytophthora capsici Crown Rot

HortScience ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 285-288 ◽  
Author(s):  
Charles S. Krasnow ◽  
Rachel P. Naegele ◽  
Mary K. Hausbeck
Keyword(s):  
Disease Susceptibility ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Fruit Rot ◽  
Controlled Environment ◽  
Post Inoculation ◽  
Phytophthora Blight ◽  
Lesion Area ◽  
Root And Crown Rot ◽  
Pericarp Thickness

Phytophthora blight is a destructive disease of cucurbits affecting the fruit, leaves, crown, and/or roots. Ten cucurbit PIs with known partial resistance to Phytophthora capsici root and crown rot were evaluated for resistance to Phytophthora fruit rot. Unwounded fruit from field-grown plants of Cucurbita moschata and C. pepo were inoculated in a controlled environment at 7 to 10 or 21 to 24 days post-pollination (dpp) with virulent P. capsici isolates to examine the effect of fruit age on disease development. Inoculated fruit were rated for lesion area and pathogen mycelial growth 7 days post-inoculation (dpi); fruit length, diameter, and pericarp thickness were also rated. Two C. pepo accessions (PI 169417 and PI 181761) had significant resistance to Phytophthora fruit rot at both 7 to 10 dpp and 21 to 24 dpp. All accessions evaluated displayed reduced disease susceptibility as the fruit aged.

scholarly journals A Rapid Technique for Multiple-race Disease Screening of Phytophthora Foliar Blight on Single Capsicum annuum L. Plants

HortScience ◽  
2010 ◽  
Vol 45 (10) ◽  
pp. 1563-1566 ◽  
Author(s):  
Ariadna Monroy-Barbosa ◽  
Paul W. Bosland
Keyword(s):  
Capsicum Annuum ◽  
Root Rot ◽  
Recombinant Inbred Lines ◽  
Phytophthora Capsici ◽  
Pepper Plant ◽  
Phytophthora Blight ◽  
Chile Pepper ◽  
Physiological Races ◽  
Foliar Blight

Phytophthora blight, caused by the oomycete Phytophthora capsici Leon., is a major disease that threatens production and long-term viability of the chile pepper (Capsicum annuum L.) industry. For each phytophthora disease syndrome such as root rot, foliar blight, and stem blight separate and independent resistant systems have evolved in the host. In addition, several physiological races of the pathogen have been identified. A novel, effective, and accurate screening technique is described that allows for multiple races to be evaluated on a single plant of C. annuum. The P. capsici resistant line Criollo de Morelos-334, a susceptible cultivar, Camelot, and three New Mexico Recombinant Inbred Lines, -F, -I, -S, were used to evaluate the new technique for phytophthora foliar blight multiple-race screening. Using three P. capsici physiological races, no interaction among the physiological races was observed with this technique. This novel technique provided a rapid disease screen evaluating multiple physiological races for phytophthora foliar blight resistance in a single chile pepper plant and can assist plant breeders in selecting for disease-resistant plants.

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 Insensitivity to Metalaxyl Among Isolates of Phytophthora capsici Causing Root and Crown Rot of Pepper in Southern Italy

Plant Disease ◽  
1998 ◽  
Vol 82 (11) ◽  
pp. 1283-1283 ◽  
Author(s):  
A. M. Pennisi ◽  
G. E. Agosteo ◽  
S. O. Cacciola ◽  
A. Pane ◽  
R. Faedda
Keyword(s):  
Mating Type ◽  
Southern Italy ◽  
Phytophthora Capsici ◽  
Crown Rot ◽  
Metalaxyl Resistance ◽  
Local Selection ◽  
Capsicum Spp ◽  
Root And Crown Rot ◽  
Single Hypha

Pepper (Capsicum annuum L.) has become an economically important crop in the coastal provinces of Catanzaro and Vibo Valentia, in Calabria (southern Italy). An old local selection Riggitano, very susceptible to root and crown rot caused by Phytophthora capsici Leonian, is the prevalent cultivar in this area. Although repeated applications of metalaxyl are used as a soil drench, severe outbreaks occur each year on greenhouse crops. To examine metalaxyl resistance in P. capsici, 60 single-hypha isolates of P. capsici were tested in vitro for their level of sensitivity to metalaxyl. The isolates were collected from 1992 to 1997, during epidemic outbreaks of root and crown rot, from two commercial greenhouse pepper crops, near Vibo Valentia and Lametia Terme (Catanzaro). Fungicide sensitivity was determined by plating mycelial plugs onto potato dextrose agar (PDA) amended with metalaxyl. The fungicide was added to PDA after autoclaving, at final concentrations of 0.1, 1, 5, 10, 50, 100, and 200 μg/ml a.i. The percentage of inhibition of radial growth on metalaxyl-amended medium compared with the growth on unamended medium was determined after 6 days of incubation in the dark at 25°C. Three replicate petri dishes were used per treatment and each test was performed twice. The isolates were paired in culture on V8 agar with isolates of P. capsici of known mating type and all proved to be A2 mating type. Significant variation was observed among the isolates tested in responce to metalaxyl. The ED50 values for in vitro inhibition of mycelial growth by metalaxyl ranged from 1 to 11 μg/ml, whereas an ED 50 value of 0.1 μg/ml had been reported for a wild-type isolate of P. capsici obtained from pepper in northern Italy (3). The variation observed among the isolates from Calabria appeared unrelated to both the geographical origin and the year of isolation. The isolates from Calabria were inhibited by between 1 and 12% at 0.1 μg/ml and by between 7 and 27% at 1 μg/ml, proving to be less sensitive to metalaxyl than isolates from Capsicum spp. originating from Central America, tested by other authors (1). According to the criterion used in a recent screening for sensitivity to metalaxyl (2), 19% of the isolates from Calabria should be considered sensitive, as they were inhibited by more than 60% at 5 μg/ml, while all the others were intermediate, as they were inhibited less than 60% at 5 μg/ml but more than 60% at 100 μg/ml. On the basis of this preliminary screening, we report the presence of insensitivity to metalaxyl in field isolates of P. capsici in southern Italy. Although no isolate tested appeared highly resistant to metalaxyl, the presence of a high proportion of isolates with an intermediate level of resistance should be a reason for the growers to use metalaxyl more cautiously to control root and collar rot. References: (1) M. D. Coffey and L. A. Bower. Phytopathology 74:502, 1984. (2) G. Parra and J. Ristaino. Plant Dis. 82:711, 1998. (3) M. L. Romano and A. Garibaldi. La difesa delle piante 3:153, 1984.

scholarly journals Response of Chile Pepper to Phytophthora capsici in Relation to Soil Salinity

Plant Disease ◽  
2004 ◽  
Vol 88 (2) ◽  
pp. 205-209 ◽  
Author(s):  
S. Sanogo
Keyword(s):  
Radial Growth ◽  
Mycelial Growth ◽  
Phytophthora Capsici ◽  
Dry Weight ◽  
Salinity Level ◽  
Growth Media ◽  
Chile Pepper ◽  
Zoospore Formation ◽  
Level Production ◽  
Pepper Plants

The response of chile pepper to salinity and infection by Phytophthora capsici was assessed under greenhouse conditions in plants susceptible or resistant to P. capsici. Additionally, the effect of salinity on mycelial growth and production of sporangia and zoospores by P. capsici was evaluated in the laboratory. Salinity treatments consisted of varying levels of electrical conductivity (from 1.8 to 14.4 dS/m) achieved by amending irrigation water or growth media with a mixture of sodium chloride and calcium chloride. In plants susceptible to P. capsici, disease severity increased by approximately 1.3 to 2.7-fold with increasing salinity level, whereas no such effect was observed in plants resistant to P. capsici. Mycelial dry weight increased by 8 to 16%, and radial growth of mycelium was augmented by 5 to 30% with increase in salinity level. Production of sporangia and zoospore formation were reduced by approximately 3 to 85 and 1 to 93%, respectively, under saline conditions. These results indicate that salinity may predispose susceptible chile pepper plants to infection by P. capsici.

Sign in / Sign up

Export Citation Format

Share Document