Screening of Virginia-Type Peanut Breeding Lines for Resistance to Cylindrocladium Black Rot and Sclerotinia Blight in the Greenhouse

Abstract Cylindrocladium black rot (CBR) caused by Cylindrocladium parasiticum and Sclerotinia blight caused by Sclerotinia minor are two economically important diseases of peanut (Arachis hypogaea) in the Virginia-Carolina production area. Developing cultivars with resistance to both diseases requires screening of new peanut breeding lines for resistance. Because field evaluations of resistance to these diseases often fail to produce usable results, greenhouse protocols were used to screen breeding lines and cultivars for resistance. For CBR, two seeds of a genotype were planted in a “cone-tainer” filled with a planting medium artificially infested with 25 microsclerotia of C. parasiticum per g of medium. After approximately 8 wk, the roots were washed and rated for degree of decay on a 0–5 proportional scale (0 = no decay to 5 = completely decayed). For Sclerotinia blight, plants were inoculated at 6 wk after planting by pushing a plug of potato dextrose agar (PDA) colonized by S. minor and protected from desiccation in a BEEM embedding capsule onto a freshly cut petiole on the main stem of the plant. Inoculated plants were placed in a mist chamber to maintain the high humidity necessary for infection. Lesion lengths were measured 4, 5, 6, and 7 days after inoculation, and areas under the disease progress curves (AUDPC) were calculated. All tests were conducted as incomplete block designs with six replications for CBR tests and four replications for Sclerotinia blight tests. Adjusted entry means were computed from each year's tests and used in summary analyses. Of the 125 breeding lines and checks tested at least once from 2003 through 2006, 51 were tested in at least two years, 34 in at least three years, and 15 lines were tested in all four years. Of the 15 lines tested in all four years, registered germplasm line N96076L had the lowest AUDPC for Sclerotinia blight (58 mm days), but had the greatest CBR root decay score (4.1 decay rating units). Several closely related breeding lines descended from a cross of N96076L and NC 12C were not significantly different from the most resistant line for either disease with scores ranging from 2.2–3.0 decay rating units for CBR and 63–99 mm days for Sclerotinia blight. Correlations of multiple-year greenhouse assay means with field disease incidence means were 0.83 for CBR and 0.35 for Sclerotinia blight. The greenhouse assay for CBR was a reasonably good predictor of field performance, but the assay for Sclerotinia blight was less reliable as a predictor.

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Sweetpotato root development influences susceptibility to black rot caused by the fungal pathogen Ceratocystis fimbriata

Phytopathology ◽

10.1094/phyto-12-20-0541-r ◽

2021 ◽

Author(s):

Camilo Humberto Parada Rojas ◽

Kenneth Pecota ◽

Christie Almeyda ◽

G. Craig Yencho ◽

Lina Quesada-Ocampo

Keyword(s):

Root Development ◽

Disease Incidence ◽

Black Rot ◽

Wild Relative ◽

Storage Root ◽

Storage Roots ◽

Ceratocystis Fimbriata ◽

Breeding Lines ◽

Below Ground ◽

Storage Root Development

Black rot of sweetpotato caused by Ceratocystis fimbriata, is an important reemerging disease threatening sweetpotato production in the United States. This study assessed disease susceptibility of the storage root surface, storage root cambium, and slips (vine cuttings) of 48 sweetpotato cultivars, advanced breeding lines, and wild relative accessions. We also characterized the effect of storage root development on susceptibility to C. fimbriata. None of the cultivars examined at the storage root level were resistant, with most cultivars exhibiting similar levels of susceptibility. In storage roots, Jewel and Covington were the least susceptible and significantly different from White Bonita, the most susceptible cultivar. In the slip, significant differences in disease incidence were observed for above and below ground plant structures among cultivars, advanced breeding lines, and wild relative accessions. Burgundy and Ipomoea littoralis displayed less below ground disease incidence as compared to NASPOT 8, Sunnyside and LSU-417, the most susceptible cultivars. Correlation of black rot susceptibility between storage roots and slips was not significant, suggesting that slip assays are not useful to predict resistance in storage roots. Immature, early developing storage roots were comparatively more susceptible than older, fully developed storage roots. The high significant correlation between storage root cross-section area and cross-sectional lesion ratio suggests the presence of an unfavorable environment for C. fimbriata as the storage root develops. Incorporating applications of effective fungicides at transplanting and during early storage root development when sweetpotato tissues are most susceptible to black rot infection may improve disease management efforts.

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First Report of Cylindrocladium Black Rot of Peanut Caused by Cylindrocladium parasiticum (Teleomorph Calonectria ilicicola) in Jiangxi Province, China

Plant Disease ◽

10.1094/pdis-11-11-1010 ◽

2012 ◽

Vol 96 (4) ◽

pp. 586-586 ◽

Cited By ~ 5

Author(s):

Y. Gai ◽

Q. Deng ◽

R. Pan ◽

X. Chen ◽

M. Deng

Keyword(s):

Southern China ◽

Disease Incidence ◽

Jiangxi Province ◽

Black Rot ◽

Brown Pigment ◽

Fruiting Bodies ◽

Calonectria Ilicicola ◽

Cylindrocladium Parasiticum ◽

Stem Lesions ◽

Reddish Orange

In July 2010, a serious disease of peanut (Arachis hypogaea) resembling Cylindrocladium black rot (CBR) was found in Longnan County, Jiangxi Province, China. Symptoms included chlorotic, yellowish and blighted leaves, and wilting of the plants. Taproots and hypocotyls were blackened and rotted. Clusters of reddish orange spherical fruiting bodies appeared in the lesions present on basal stems, pegs, pods, and roots of peanut. Disease incidence reached as much as 50% in some patches of the field. Plants with symptoms were sampled from fields. Microscopic examination revealed that the reddish orange, spherical fruiting bodies were the perithecia and measured 461.6 (337.5 to 609.4) × 395.5 (309.4 to 496.9) μm. With gentle pressure, asci and ascospores were exuded from perithecia. The asci were hyaline, thin walled, and long stalked. Ascospores were hyaline, falcate with one septum, and measured 43.5 (27.3 to 54.5) × 5.6 (4.1 to 6.8) μm with a length/width (L/W) ratio of 7.8 ± 1.3. A fungus with white-to-pale buff border mycelia and yellowish brown pigment was consistently isolated from the edge of basal stem lesions on potato dextrose agar at 25°C. Mycelia grew at temperatures ranging from 8 to 32°C and the optimum was 25 to 26°C. To determine the species, single-conidial isolates of the fungus were cultured on carnation leaf agar for 7 days at 25°C and 12 h of light/dark conditions. Conidia were hyaline, cylindrical with one to three septa (mostly three septa), and measured 49.3 (27.3 to 70.9) × 5.9 (4.1 to 6.8) μm with L/W ratio of 8.4 ± 1.6. Vesicles were globose and measured 5.5 to 10.9 μm in diameter. The fungus was identified as Cylindrocladium parasiticum (teleomorph Calonectria ilicicola) (1,2). A PCR assay was conducted on one representative isolate (JXLN32) by analyzing multilocus sequences of the TUB2 (coding β-tubulin protein), ACT (coding actin), and CaM gene (coding calmodulin protein) and were amplified and sequenced using the primers reported by Crous et al. (3). Sequences of the studied DNA regions were submitted to GenBank (Accession Nos. TUB2: JF429649; ACT: JQ070809; and CaM: JQ070808). BLAST searches with the existing sequences in GenBank showed that there was 99 to 100% identity with the existing sequences of C. ilicicola (GenBank Accession Nos. TUB2: AY725643; ACT: GQ280446; and CaM: GQ267402). To complete Koch's postulates, inoculum was prepared by mixing the microsclerotia (MS) suspension of the isolate (JXLN32) with soil at a proportion of 10 MS per g of soil. Ten replicate plastic pots containing five peanut seeds (cv. Yueyou 7) each were planted and placed in a glasshouse at 25 ± 2°C. The same number of peanut seeds was used as an uninoculated control. Typical basal stem and roots rot symptoms of CBR were observed in 2 months and C. parasiticum was reisolated from these inoculated diseased plants. No symptoms were detected on the control plants. To our knowledge, this is the first finding of Cylindrocladium black rot in Jiangxi Province, which is the main peanut-producing area in China. The disease has been previously reported in Guangdong Province in southern China but is not known elsewhere (4). Because of its ability to spread through seed and soil and its destructive potential, this pathogen may pose a serious threat to peanut production in China. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Stud. Mycol. 50:415, 2004. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

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New Sources of Cylindrocladium Black Rot Resistance among Runner-Type Peanut Cultivars

Peanut Science ◽

10.3146/ps11-10.1 ◽

2012 ◽

Vol 39 (1) ◽

pp. 38-42 ◽

Cited By ~ 2

Author(s):

W. D. Branch ◽

T. B. Brenneman

Keyword(s):

Test Site ◽

Field Trials ◽

Black Rot ◽

Breeding Lines ◽

Cylindrocladium Parasiticum ◽

Arachis Hypogaea L ◽

Combined Test ◽

History Of ◽

Peanut Cultivars ◽

Wilt Virus

Abstract Cylindrocladium Black Rot (CBR) caused by Cylindrocladium parasiticum Crous, Wingfield, & Alfenas syn. C. crotalariae (Loos) Bell & Sobers is a major disease problem in southeast U.S. peanut (Arachis hypogaea L.) production. Field trials were conducted for two-years (2008-09) at a test site (Gibbs Farm) that has a long history of continuous peanut production near the Univ. of Georgia, Coastal Plain Expt. Station, Tifton, GA to evaluate for CBR resistance among new runner-type peanut cultivars. All plots were artificially inoculated with microsclerotia of C. parasiticum after planting each year. Significant differences (P≤0.05) were found among the cultivars and advanced breeding lines for both CBR resistance and tomato spotted wilt virus (TSWV) resistance which was also present each year, but the predominant disease was CBR. Georgia Greener, Georgia-06G, Georgia-07W, Georgia-02C, and Carver were consistently found to be the most CBR resistant; whereas, C-99R and Tifguard were the most susceptible each year. In separate CBR tests conducted in 2009 and 2010 at a different location (Blackshank Farm), Georgia Greener also had the least difference, and Tifguard had the greatest difference, between C. parasiticum inoculated versus non-inoculated plots for pod yield. These combined test results demonstrate that useful levels of CBR resistance are currently available in promising new runner-type peanut cultivars.

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Greenhouse Evaluation of Section Arachis Wild Species for Sclerotinia Blight and Cylindrocladium Black Rot Resistance

Peanut Science ◽

10.3146/ps13-02.1 ◽

2014 ◽

Vol 41 (1) ◽

pp. 17-24 ◽

Cited By ~ 2

Author(s):

S. P. Tallury ◽

J. E. Hollowell ◽

T. G. Isleib ◽

H. T. Stalker

Keyword(s):

Genetic Variability ◽

Wild Species ◽

Insect Pests ◽

Blight Resistance ◽

Rectangular Lattice ◽

Black Rot ◽

Sources Of Resistance ◽

Arachis Species ◽

Sclerotinia Blight ◽

Mist Chamber

ABSTRACT Wild Arachis species from section Arachis have been promoted as sources of resistance to common peanut diseases and insect pests. The objective of our study was to identify wild Arachis species with resistance to Sclerotinia blight and Cylindrocladium black rot (CBR). One hundred and ten accessions/entries from 23 Arachis species including A. hypogaea were evaluated in the greenhouses at North Carolina State University between January and March of 2010 in a 11×10 rectangular lattice experimental design with 4 replications for Sclerotinia blight and 6 replications for CBR. For the Sclerotinia blight test, seeds were planted in 10 cm clay pots and 8-wk-old plants were inoculated in a mist chamber with BEEM capsules containing the fungus inserted on the petioles of the 4th leaf from the apex on the primary branch. Lesion lengths were measured 4, 5, 6, and 7 d after inoculation, and areas under the disease progress curves (AUDPC) were calculated. For the CBR test, seeds were planted in soil mixed with microsclerotia (25/g) in cone-tainers partly immersed in water. Root damage was recorded after 60 d on a 0–5 proportional scale (0 = no decay to 5 = completely decayed). Data analysis indicated significant (p<0.05) variation among and within Arachis species for both diseases. Arachis glandulifera exhibited the highest level of Sclerotinia blight resistance followed by A. correntina, A. herzogii, and A. helodes, although the last three species were not significantly different from A. hypogaea. Overall, low genetic variability for Sclerotinia blight resistance was observed among the wild species accessions. For CBR, A. valida, A. cruziana, A. microsperma, A. williamsii, A. kempff-mercadoi, A. kuhlmannii, A. helodes, A. cardenasii and A. correntina formed the most resistant group with A. hypogaea in the most susceptible group. Overall, significant genetic variability for CBR resistance was found among the different wild species accessions. However, not all accessions within a species were resistant to either disease, and most accessions that were resistant to one disease were susceptible to the other.

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Transgressive Segregation and Long-Term Consistency for High TSWV Field Resistance in the ‘Georgia-06G’ Peanut Cultivar

Plant Health Progress ◽

10.1094/php-04-18-0018-rs ◽

2018 ◽

Vol 19 (3) ◽

pp. 201-206 ◽

Cited By ~ 1

Author(s):

W. D. Branch ◽

A. K. Culbreath

Keyword(s):

Disease Incidence ◽

The United States ◽

Transgressive Segregation ◽

Field Resistance ◽

Breeding Lines ◽

Tomato Spotted Wilt ◽

Arachis Hypogaea L ◽

Production Area ◽

Wilt Virus

Tomato spotted wilt disease caused by tomato spotted wilt virus (TSWV) is a major peanut (Arachis hypogaea L.) production problem in the United States. TSWV has become endemic since the mid-1980s in the southeastern U.S. peanut production area. ‘Georgia-06G’ is a large-seeded, TSWV-resistant, runner-type peanut cultivar, whereas ‘Georgia Greener’ is a sister line with a smaller seed size than Georgia-06G. Both Georgia-06G and Georgia Greener have greater TSWV general field resistance with higher yields, total sound mature kernels grade, and dollar values than the parents (‘Georgia Green’ and ‘C-99R’), which shows transgressive segregation for these desirable quantitative traits. Therefore, the objective of this 12-year study was to evaluate the higher TSWV host-plant resistance found in the Georgia-06G over time compared with many other runner- and virginia-type peanut cultivars and advanced breeding lines. Despite yearly variability in TSWV and total disease incidence, the data indicate that Georgia-06G exhibited long-term high TSWV and total disease field resistance at midseason and late season, respectively. Georgia-06G was also found to have among the highest pod yield and dollar value every year. The higher general TSWV field resistance of Georgia-06G appears to be consistent across many years and locations, similar to the moderate TSWV resistance in Georgia Green.

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First Report of Peanut Cylindrocladium Black Rot Caused by Cylindrocladium parasiticum in Fujian Province, Eastern China

Plant Disease ◽

10.1094/pdis-11-11-0982 ◽

2012 ◽

Vol 96 (4) ◽

pp. 583-583 ◽

Cited By ~ 4

Author(s):

R. Pan ◽

Q. Deng ◽

D. Xu ◽

C. Ji ◽

M. Deng ◽

...

Keyword(s):

Southern China ◽

Disease Incidence ◽

Eastern China ◽

Black Rot ◽

Brown Pigment ◽

Fujian Province ◽

First Report ◽

Calonectria Ilicicola ◽

Cylindrocladium Parasiticum ◽

Wheat Kernels

During late July and early August of 2010, a serious disease of peanut (Arachis hypogaea L.) resembling Cylindrocladium black rot (CBR) was found in Longyan City, Fujian Province of Eastern China. Aboveground symptoms were chlorosis and yellowing of leaves, a black rot of the basal stem and pegs, and wilting of the vines. Underground plant parts (including pods, pegs, taproots, and hypocotyls) were blackened and rotted. Orange-to-reddish spherical fruiting bodies appeared on the lesions of the basal stems and pegs of peanut. Disease incidence was approximately 20%. A fungus was consistently isolated from the edge of lesions on potato dextrose agar (PDA) amended with streptomycin and incubated at 25°C. The fungus produced white-to-pale buff mycelia with a yellowish brown pigment. Optimum growth of the fungus on PDA was at 25 to 30°C. Conidiophores were borne laterally on a stipe that terminated in a hyaline, globose vesicle measuring 5.5 × 10.9 μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, slightly wider at the base than at the apex, with one to three septa (mostly one septa), and measured 27.3 to 70.9 × 4.1 to 8.2 μm. Orange-to-reddish perithecia were readily formed in old cultures. The perithecia were subglobose to oval or obovate and measured 215.6 to 609.4 × 309.4 to 496.9 μm. The asci were hyaline, clavate, thin walled, long stalked, with each containing eight ascospores. Ascospores were hyaline, falcate, had one septum, and measured 27.3 to 54.5 × 4.1 to 6.8 μm. The fungus was identified as Cylindrocladium parasiticum Crous, M.J. Wingfield, & Alfenas (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment was amplified using the T1/Bt2b primers (3) and sequenced. The sequences of three isolates (GenBank Accession Nos. JF343965, JF429656, and JF429657), when compared with existing sequences in GenBank, had 95 to 99% sequence identity with Calonectria ilicicola (GenBank Accession Nos. AY725643 and AY725639). Pathogenicity tests were conducted by first culturing the fungus on wheat kernels for 2 weeks. Inoculated kernels were then used as inoculum and mixed with sterilized soil in a proportion of 1:20 by weight in plastic pots (10 × 9 cm). Noninoculated wheat kernels were mixed with sterilized soil in the same proportion and served as the control. Two-week-old peanut seedlings (cv. Yueyou No. 7) were transplanted into inoculated or noninoculated pots. There were five plants per pot and each treatment was replicated four times. The plants were incubated in a greenhouse at 25 ± 2°C. All of the treated plants exhibited typical basal stem and root rot symptoms of CBR 2 weeks after inoculation, while all of the control plants remained healthy. C. parasiticum was reisolated from the diseased plants. To our knowledge, this is the first report of CBR on peanut in Fujian Province in Eastern China. The disease has been previously reported in Guangdong Province in Southern China but is not known elsewhere (4). This pathogen may pose a serious threat to peanut production in China, where peanut is an important crop. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

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Resistance of Peanut to Sclerotinia Blight and the Effect of Acibenzolar-S-methyl and Fluazinam on Disease Incidence

Plant Disease ◽

10.1094/pdis.2002.86.12.1315 ◽

2002 ◽

Vol 86 (12) ◽

pp. 1315-1317 ◽

Cited By ~ 18

Author(s):

A. V. Lemay ◽

J. E. Bailey ◽

B. B. Shew

Keyword(s):

North Carolina ◽

Field Test ◽

Fungal Pathogen ◽

Yield Loss ◽

Disease Incidence ◽

Breeding Line ◽

Breeding Lines ◽

Sclerotinia Blight ◽

High Yields ◽

Plant Activator

Sclerotinia minor, a soilborne fungal pathogen of peanut, can cause serious yield loss in North Carolina. A field test was implemented to study genotype reaction, and the effect of aciben-zolar-S-methyl (a plant activator) and the fungicide fluazinam on disease incidence. In all, 13 genotypes in 1997 and 12 genotypes in 1998 were evaluated. Three applications of acibenzolar-S-methyl (0.14 kg a.i./ha) or fluazinam (0.58 kg a.i./ha) were made on a calendar-based schedule. Disease ratings were made weekly in 1997 and every other week in 1998. Fluazinam suppressed disease at all sites and increased yield at two of three locations. Acibenzolar-S-methyl had no effect on disease incidence or yield. The advanced breeding line N92056C and cvs. Tam-run 98 (TX 901417) and Perry (N93112C) had moderate to high levels of resistance to S. minorand produced high yields compared with susceptible cv. NC 7. Lines derived from wild species also demonstrated moderate to high levels of resistance relative to NC 7 and represent potential breeding lines.

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First Report of Neocosmospora striata Causing Peanut Pod Rot in China

Plant Disease ◽

10.1094/pdis-06-11-0461 ◽

2012 ◽

Vol 96 (1) ◽

pp. 146-146 ◽

Cited By ~ 1

Author(s):

W. M. Sun ◽

L. N. Feng ◽

W. Guo ◽

D. Q. Liu ◽

Z. H. Yang ◽

...

Keyword(s):

Yellow River ◽

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Black Rot ◽

First Report ◽

Cylindrocladium Parasiticum ◽

Arachis Hypogaea L ◽

Rot Disease ◽

Template Dna

In 2008, an outbreak of pod rot of peanut (Arachis hypogaea L.) occurred on most of the peanut cultivars in the Old Yellow River drainage area, the largest peanut-growing region in China. Disease incidence reached as high as 90% in some fields, causing severe yield losses. The black rot of pods and blackened, nonrotting taproots is similar to symptoms of peanut black rot caused by Cylindrocladium parasiticum, but the reddish orange perithecia of C. parasiticum were not found on the taproots close to the surface of the soil. The foliage of affected plants was generally asymptomatic, but some plants turned greener. This pod rot disease was further investigated in 2008 and 2010. Twenty-three Fusarium-like isolates were obtained from symptomatic, surface-disinfested pods with a frequency of 82%. These isolates were fast growing, with flat, thin, and grayish white colonies when cultured on potato dextrose agar (PDA) at 28°C for 3 to 4 days. The hyaline, elongated to cylindrical conidia, aggregated in slimy heads on conidiogenous cells developed from undifferentiated hyphae when observed with the light microscope. The size of conidia (single celled or one septum) varied from 3 to 9 μm long and 1.5 to 3.5 μm wide on the basis of the measurement of 50 spores. Some conidia appeared slightly curved. Ascomata formed within 10 to 14 days, with a punctate appearance on the colony. The cerebriform ascomata were dark brown, pyriform, ostiolate, glabrous, 120 to 170 × 90 to 130 μm, and with necks 30 to 50 μm long. Asci measured 60 to 90 × 6 to 10 μm, were cylindrical to cylindric-clavate, thin walled, and had an apical ring. Ascospore arrangement was obliquely uniseriate or partially biseriate, very pale yellow to hyaline, ellipsoidal, and measured 8 to 12 × 4.5 to 6 μm. Some spores had a median transverse straight or curved septum and were slightly constricted at the septum, with 6 to 10 thin, transverse, hyaline flanges. Morphological characteristics of the isolates with ascomata dark brown and ascospores with 6 to 10 transverse hyaline flanges matched the description for Neocosmospora striata (1). The internal transcribed spacer (ITS) region of rDNA was amplified from extracted template DNA with primer pairs ITS4/ITS5 and sequenced. A 591-bp amplicon (GenBank Accession No. HM461900) had 99% sequence identity with Fusarium solani (HQ607968 and HQ608009) and N. vasinfecta (GU213063), which indicated that these fungi belong to the genus Neocosmospora or Fusarium, although there is no direct sequence evidence that they are N. striata. N. striata has only been previously reported in Japan (2). This species is unique because of the dark brown ascomata and there is no comparable species (1). Koch's postulates were completed by surface-disinfesting 80 peanut pods of cv. Jihua 9813 and soaking them in conidial suspensions (105 conidia/ml) for 2 min. Another 80 other pods soaked in sterile water served as controls. All peanuts were incubated in moist petri dishes under darkness at 28°C. Symptoms similar to those originally observed in the field formed within 10 days on all inoculated peanut pods and not the controls. N. striata was reisolated from all affected peanut pods. To our knowledge, this is first report of N. striata causing peanut pod rot in China and the first description of the anamorph of the fungus. References: (1) P. F. Cannon et al. Trans. Br. Mycol. Soc. 82:673, 1984. (2) S. Udagawa et al. Trans. Mycol. Soc. Jpn. 16:340, 1975.

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Field Performance of Advanced Runner- and Virginia-Type Peanut Breeding Lines During Epidemics of TSWV

Peanut Science ◽

10.3146/i0095-3679-24-2-13 ◽

1997 ◽

Vol 24 (2) ◽

pp. 123-128 ◽

Cited By ~ 5

Author(s):

A. K. Culbreath ◽

J. W. Todd ◽

D. W. Gorbet ◽

F. M. Shokes ◽

H. R. Pappu

Keyword(s):

Disease Incidence ◽

Western Flower Thrips ◽

Field Performance ◽

Breeding Lines ◽

Flower Thrips ◽

Tomato Spotted Wilt ◽

Arachis Hypogaea L ◽

Tobacco Thrips ◽

Peanut Production ◽

Production Areas

Abstract Spotted wilt, caused by tomato spotted wilt tospovirus (TSWV), has become a major problem in peanut- (Arachis hypogaea L.) producing areas of the southern U.S. Development of cultivars with resistance to TSWV appears to be among the most promising methods for managing this disease. As part of efforts toward characterizing breeding lines with potential for release as cultivars, epidemics of spotted wilt were monitored in field plots of runner-type peanut cultivars Southern Runner and Florunner and advanced breeding lines: 79/4-6-2-1-1-Z16-b2-B (virginia-type), F 84/23-11-1-1-1-b2-B (runner-type), and F 84/28-5-5-2-2-1-b2-B (runner-type), F 84/28-5-4-2-2-b3-B (runner-type). The tests were conducted near Attapulgus, GA and Marianna, FL in 1995 and 1996. In 1996, the tests also included the runner-type cultivar AT-108. Epidemics of spotted wilt were suppressed in F 79/4-6-2-1-1-Z16-b2-B, F 84/23-11-1-1-1-b2-B, F 84/28-5-5-2-2-1-b2-B, and Southern Runner in comparison to those in Florunner. Final disease incidence and/or final disease intensity ratings in F 79/4-6-2-1-1-Z16-b2-B and F 84/23-11-1-1-1-b2-B were similar to those of Southern Runner. In 1996, final spotted wilt intensity ratings in F 84/28-5-4-2-2-b3-B and AT-108 did not differ from those of Florunner. Yields of F 79/4-6-2-1-1-Z16-b2-B and F 84/23-11-1-1-1-b2-B were superior to those of Florunner in three of the four tests. No differences were found among the genotypes in numbers of adults of tobacco thrips (Frankliniella fusca) or western flower thrips (F. occidentalis), and differences in numbers of larvae of Frankliniella spp. were few and not consistent. There was no evidence that differences in final disease incidence or disease intensity ratings were due to differential preference by thrips or to suitability for thrips reproduction. F 79/4-6-2-1-1-Z16-b2-B and F 84/23-11-1-1-1-b2-B represent potential tools for management of spotted wilt in peanut production areas of the southeastern U.S.

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Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽

10.1094/pdis-06-10-0454 ◽

2011 ◽

Vol 95 (3) ◽

pp. 263-268 ◽

Cited By ~ 4

Author(s):

S. K. Gremillion ◽

A. K. Culbreath ◽

D. W. Gorbet ◽

B. G. Mullinix ◽

R. N. Pittman ◽

...

Keyword(s):

United States ◽

Disease Resistance ◽

Leaf Spot ◽

Field Experiments ◽

Disease Incidence ◽

The United States ◽

Yield Potential ◽

Cercospora Arachidicola ◽

Breeding Lines ◽

Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

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