Sclerotinia Blight Research Articles

Efficacy of Different Botanicals Extracts Against Sclerotinia Blight of Brinjal (Sclerotinia sclerotiorum) under In vivo Conditions

Among the various diseases the sclerotinia blight (Sclerotinia sclerotiorum) is an important disease which causes loss in quality and quantity of fruits of brinjal. In between crop seasons, the species of Sclerotinia mainly survive through sclerotia which may be present on soil surface in unploughedfields or in crop debris or as admixture with the seed. In past, brinjal sclerotinia blight disease has been managed by various method, viz. chemical, cultural, biological Control and use of resistant varieties. However, it was observed that pathogens have developed resistance against regular use of chemicals. The uses of alternative management are best option for management of this disease such as resistant varieties and bio-agent/biological control.Between crop seasons, Sclerotinia species rely on sclerotia, which can be found on the surface of the soil in unploughed fields, in crop debris, or as an admixture with the seed. In the past, brinjal sclerotinia blight disease was treated with a variety of methods, including chemical, cultural, and biological treatments. Control and the utilisation of resistant cultivars are also important. Pathogens, on the other hand, have acquired resistance to the application of chemicals on a frequent basis. Alternative management strategies, such as resistant varieties and bio-agent/biological control, are the greatest options for managing this disease.Five plant extracts viz., Garlic, Neem, Ocimum, Dhatura, Onion were tested in vivo against Sclerotiniasclerotiorumat 10 per cent and 15 per cent concentration. All plant extracts were more or less effective and exhibited reduction in sclerotinia blight disease incidence. The effectivity of extracts increased with an increase in concentration. At ten per cent concentration, minimum disease incidence was found in Garlic (18.85%) followed by Neem (20.21%), Ocimum (22.67%), Dhatura (24.07%) and Onion (28.11%) extract as compared to untreated plants (33.07%). Maximum disease severity control (42.99%) was recorded in Garlic followed by Neem (38.88%), Ocimum (31.44%), Dhatura (27.14%) While minimum was recorded in Onion (14.99%). At 15% concentration the most effective was found in garlic which exhibited maximum disease severity control (50.57%) was recorded in Garlic followed by Neem (47.69%), Ocimum (38.50%), Dhatura (37.38%) While minimum was recorded in Onion (23.69%).

RAS signalling genes can be used as host-induced gene silencing targets to control fungal diseases caused by Sclerotinia sclerotiorum and Botrytis cinerea.

Sclerotinia sclerotiorum causes white mold (also called stem rot, Sclerotinia blight, etc.) in many economically important plants. It is a notorious soilborne fungal pathogen due to its wide host range and ability to survive in soil for long periods of time as sclerotia. Although host-induced gene silencing (HIGS) was recently demonstrated to be an effective method for controlling white mold, limited gene targets are available. Here, using a forward genetics approach, we identified a RAS-GTPase activating protein, SsGAP1, which plays essential roles in sclerotia formation, compound appressoria production and virulence. In parallel, as revealed by our knockout analysis, the SsGAP1 ortholog in Botrytis cinerea, BcGAP1, plays similar roles in fungal development and virulence. By knocking down SsRAS1 and SsRAS2, we also revealed that both SsRAS1 and SsRAS2 are required for vegetative growth, sclerotia development, compound appressoria production and virulence in S. sclerotiorum. Due to the major roles these RAS signalling components play in Sclerotiniaceae biology, they can be used as HIGS targets to control diseases caused by both S. sclerotiorum and B. cinerea. Indeed, when we introduced HIGS constructs targeting SsGAP1, SsRAS1 and SsRAS2 in Nicotiana benthamiana and Arabidopsis thaliana, we observed reduced virulence. Taken together, our forward genetics gene discovery pipeline in S. sclerotiorum is highly effective in identifying novel HIGS targets to control S. sclerotiorum and B. cinerea.

Characterization of Native Fluorescent Pseudomonads against Sclerotinia Blight of Brinjal (Solanum melongena L.)

Brinjal (Solanum melongena L.) is one of the most common and known rich source of vitamin B1 (Thiamin), dietary fibre, manganese, niacin (vitamin B3), copper, vitamin B6 (pyridoxine), folate (vitamin B9), potassium, Vitamin K. Brinjal cultivation is affected by several pests and diseases. Sclerotinia blight is one of the most destructive diseases of brinjal caused by Sclerotinia sclerotiorum (Lib) de Bary. Under the present investigation two isolates of Fluorescent Pseudomonads (FLPs) viz., FLP-Brinjal 2020-1 and FLP-Brinjal 2020-2, were evaluated against Sclerotinia sclerotiorum (SCL)under in vivo and in vitro conditions using dual culture, inverted plate assay. FLP-Brinjal 2020-2 gave maximum inhibition over the control followed by FLP-Brinjal 2020-1 against the pathogen in in vitro condition. Experiments conducted in pluck trays indicated that FLP-Brinjal 2020-2 was superior with least sclerotinia blight incidence (20.53%).The identity and diversity among the FLP isolates were examined by sequence analysis of 16s rRNA gene. The gene was amplified by PCR using primers pair, 27 F/1492 R. Amplified DNA products were sequenced and analysed by BLAST (BLASTn) programme at NCBI database for species identification. Among the 10 FLPs isolates assessed 9 were found to have maximum similarity with Pseudomonas aeruginosa. FLP 2020-2 and FLP 2020-1 were found to be Pseudomonas fluorescence which is in confirmation with the morphological observations. Significant diversity among the isolates was observed when dendrogram of the sequence was plotted using CLUSTAL W.

Two QTLs govern the resistance to Sclerotinia minor in an interspecific peanut RIL population

AbstractSclerotinia blight is a soilborne disease caused by Sclerotinia minor Jagger and can produce severe decrease in yield. Cultural management strategies and chemical treatment are not completely effective; therefore, growing peanut‐resistant varieties is likely to be the most effective control method for this disease. Sclerotinia blight resistance has been identified in wild Arachis species and further transferred to peanut elite cultivars. To identify the genome regions conferring Sclerotinia blight resistance within a tetraploid genetic background, this study evaluated a population of recombinant inbred lines (RIL) with introgressed genes from three wild diploid species: A. cardenasii, A. correntina, and A. batizocoi. Two consistent quantitative trait loci (QTLs), qSbIA04 and qSbIB04 located on chromosomes A04 and B04, respectively, were identified. The QTL qSbIA04 was mapped at 56.39 cM explaining 29% of the phenotypic variance and qSbIB04 was mapped at 13.38 cM explaining 22% of the overall phenotypic variance.

First Report of Sclerotinia Blight on Peanut Caused by Sclerotinia sclerotiorum in Qinghai Province, China.

Historically, peanut has not been produced in Qinghai province located in Northwest China because of the high elevation and cold climates. However, since 2020 field studies have been conducted to evaluate peanut cultivars for suitability to field production. In 2020, peanut cultivation was successful for the first time in Haidong city, Qinghai province, China. In August 2020, brown, irregular-shaped lesions were observed on peanut stems from Qinghai province in China. In the early stage, the watersoaked spots were formed on the stems, then lesions expanded rapidly and became brown. In advanced stages of the disease, stems became bleached and eventually died. The inside of the stems was rotten and hollow, and the diseased stem wilted and died. White hyphae and black irregular shaped sclerotia were observed on the infected stems. Finally, local or whole plant rotted and died at the end. Approximately 10% of the plants in a field were infected. Symptomatic stems were cut into small pieces, disinfected with 75% ethanol for 1 minute, 0.5% NaClO for two minutes, and sterile water for three times. Pieces then were plated on potato dextrose agar (PDA) media and incubated at 25°C in darkness. Fungal colonies were initially white, becoming gray, then black sclerotia (2.4 to 6.0 mm in diameter) were appeared at the edge of colonies. Genomic DNA of the pure cultures of an isolate (ZHX7) was extracted and PCR was carried out using glyceraldehydes-3-phosphate dehydrogenase gene (G3PDH) region primers G3PDH-F/G3PDH-R, heat-shock protein 60 gene (HSP60) region primers HSP60-F/HSP60-R, and DNA-dependent RNA polymerase subunit gene (RPB2) region primers RPB2-F/RPB2-R (Staats et al., 2005), respectively. G3PDH region (Accession No. MZ388475) showed 99.44% sequence identity (887 bp out of 909 bp) to Sclerotinia sclerotiorum (Accession No. AJ705044, 887 bp out of 887 bp). HSP60 region (Accession No. MZ388476) showed 99.90% sequence identity (972 bp out of 984bp) to S. sclerotiorum (Accession No. AJ716048, 972 bp out of 980 bp). RPB2 region (Accession No. MZ388477) showed 100.00% sequence identity (1096 bp out of 1129 bp) to S. sclerotiorum (Accession No. AJ745716, 1096 bp out of 1096 bp). Phylogenetic analysis was done using Neighbor-Joining (NJ) analysis based on those gene sequences. The isolate was identified as S. sclerotiorum based on molecular analysis and morphological characteristics. For pathogenicity assay, ten-days-old potted peanut (Luhua No.12) seedlings were inoculated with one mycelial plug (8 mm in diameter ) by placing the inoculum on the base of the stem in a growth chamber (30°C in the day and 25°C at night, a 12-h photoperiod and 80% RH). All inoculated seedlings exhibited typical basal stem rot, and root showed different degrees of damage, and wilted 5 days after inoculation. No symptoms were observed on control plants treated with sterile distilled mycelial plugs, and S. sclerotiorum was consistently re-isolated from symptomatic tissue. S. sclerotiorum has been reported on peanut in Northeastern China (Yan et al., 2005). To our knowledge, this is the first report of S. sclerotiorum causing Sclerotinia Blight on peanut in Qinghai province, China. The peanut planting area in Qinghai has been further expanded this year, and S. sclerotiorum has a broad host range (Boland and Hall, 1994), so Sclerotinia Blight is a potential threat to peanut production, and as a result, it is critical for commercial producers to monitor plants for S. sclerotiorum.

Comparative evaluation of diseases affection of winter and spring false flax (Camelina sativa (L.) Crantz) in the Krasnodar region

We carried out the phytosanitary monitoring of winter and spring false flax (Camelina sativa (L.) Crantz) in the central zone of the Krasnodar region to comparatively evaluate the diseases affection for effective breeding work to develop varieties resistant to the most common and dangerous crop diseases. We noted the same frequency of occurrence of Alternaria blight, Fusarium blight, Sclerotinia blight, bacterial blight and phytoplasma disease on both forms of false flax. We observed the differences between winter and spring false flax in affection by downy mildew, powdery mildew, and white rust. The most harmful of the frequent diseases were downy mildew on winter false flax, and Fusarium blight on spring false flax, so one of the directions in breeding work with false flax is to develop varieties resistant to the affection by these diseases.

Identification of QTLs associated with Sclerotinia blight resistance in peanut (Arachis hypogaea L.)

Sclerotinia blight caused by Sclerotinia minor (Jagger) is a significant threat to peanut production; therefore varietal improvement toward this disease is needed. To date, there have been no reported quantitative trait locus (QTL) associated with Sclerotinia blight resistance in peanut. Hence, the objective of this study was to identify QTLs for Sclerotinia blight resistance. A total of 90 F2:6 recombinant inbred lines, derived from a released cultivar Tamrun OL07 and a breeding line Tx964117, were used as mapping population and field experiments were conducted in 2010, 2012 and 2018 at the Texas A&M AgriLife Research and Extension Center at Stephenville, Texas. A genetic map was developed using 1211 SNP markers based on double digest restriction-site associated DNA sequencing (ddRAD-Seq). In total, seven QTLs were identified, two QTLs from 2010 and five QTLs from 2018, with LOD score values of 3.2 to 7.2 and explaining 6.6–25.6% phenotypic variance. Among these QTLs, three were detected in common by WinQTLCart and R/qtl. Interestingly, one of the QTLs coincides with a previously reported peanut Leaf spot resistance QTL. The findings from this study not only provide insights into disease resistant QTLs in peanut but can also be used as potential targets for breeding programs to enhance Sclerotinia blight resistance through molecular breeding.

Screening US peanut mini-core accessions for resistance to Sclerotinia blight caused by Sclerotinia sclerotiorum

Sclerotinia blight is a destructive disease of peanut caused by Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotinia minor Jagger. Crop management practices are routinely used to control Sclerotinia blight, however, development of resistant cultivars together with crop management practices may provide a lasting solution to control the disease in peanut fields. In this study, 95 accessions of United States’ peanut mini-core collection were evaluated using detached leaflet and whole plant inoculation methods under greenhouse conditions. The area of detached leaflet infected was scored using a scale from 0 (no disease) to 4 (76%–100% leaflet area infected). Whole plants were evaluated based on disease severity index (DSI) from 0% (no disease) to 100% (entire plants infected). In the detached leaflet inoculation method, accessions PI-268586, PI-268696, PI-356004, PI-372305, and PI-429420 had the lowest average disease score of 2.7. In the whole plant inoculation method, accessions PI-200441, PI-259658, PI-319770, PI-323268, and PI-337293 had the lowest DSI from 86% to 90%. The two inoculation methods resulted in different set of accessions with the lowest disease level. These results may reflect differences in disease pressure between the two screening methods.

First Report of Sclerotinia Blight Caused by Sclerotinia sclerotiorum on Oriental Tobacco in the Yunnan Province of China

Yunnan Province is a major oriental tobacco (OT) production area with >90% of China’s output (Qu et al. 2014). In the spring of 2018 and 2019, we conducted OT disease surveys in Mengtong, Baoshan, Yunnan Province, and we found an unknown disease displaying rotting, wilting, and blighting in two fields (24°32′37″ N, 99°37′34″ E; 24°32′46″ N, 99°37′31″ E; ∼2,000 m²). Average incidence was 3.0 and 8.4%, respectively. Disease development began with water-soaked, oval or circular spots with white centers and olive-green edges that formed on the wounds of stems and petioles near the soil, and infected stems subsequently became bleached and died. In the late phases, white cottony mycelium appeared on the dead tissues. Spherical to cylindrical black sclerotia (5.0 to 17.0 × 3 to 7 mm; avg. 9.1 × 4.5 mm; n = 50) were observed inside and on the surface of stems. To isolate the pathogen, five and four infected samples were collected from fields in 2018 and 2019, respectively. Tissue sections (5 mm²) with typical symptoms were surface disinfected in 75% ethanol for 5 s and 0.5% NaOCl for 1.5 min, rinsed in sterilized distilled water three times, and dried. Tissues were placed on PDA plates and cultured at 25°C for 3 days in the dark. Hyphal tips were transferred to fresh PDA plates. Thin, cottony-white, fluffy mycelia grew to cover the Petri dish (9 cm diam.) in 3 to 4 days. Irregular white immature sclerotia were produced 4 to 5 days later on the edges of the plates. After 7 to 14 days, abundant spherical or oval black sclerotia of 2.4 to 5.0 × 1.4 to 3.8 mm (avg. 3.4 × 2.6 mm, n = 50) were formed. Morphology of all isolates was similar to Sclerotinia sclerotiorum (Lib.) de Bary. To confirm the pathogen, we extracted genomic DNA from the mycelia of isolate HP-1 using a Fungal DNA Extraction Kit (Omega). The ITS region and partial β-tubulin gene sequence of HP-1 were amplified with primers ITS1/ITS4 and Bt2a/Bt2b, respectively (Doyle and Doyle 1987; Glass and Donaldson 1995). PCR amplicons were purified and cloned into pMD19-T simple vector (Takara Biomedical) for Sanger dideoxy sequencing at Shanghai Life Technology Co. BLASTn search revealed the 462-bp ITS sequence (MK656936.1) was identical to S. sclerotiorum (MK527226.1, MK010971.1, MG931017.1, etc.), and the 472-bp partial β-tubulin sequence (MN295984.1) was too (MG931018.1, KX781302.1, KF545201.1, etc.). Koch’s postulates were fulfilled by inoculation and reisolation of HP-1 from five plants. Five mycelial plugs, 8 mm diameter, from 5-day-old culture grown on PDA were used to inoculate the lower stems of five 45-day-old susceptible plants (BASMA-1) and wrapped with wet sterilized cotton. PDA plugs without fungi were controls. Plants were maintained in a greenhouse at 25°C with a 12-h photoperiod. Five days after inoculation, all inoculated stems became water-soaked brown and covered with white mycelia. Symptoms typical of Sclerotinia blight (SB) on stems were observed 10 days after inoculation. S. sclerotiorum was consistently reisolated. No symptoms developed on the controls. Similar results were obtained in three independent experiments. Seedling blight caused by S. sclerotiorum has been recorded on flue-cured tobacco in Brazil, the United States, and Jilin and Anhui Provinces of China (Gao et al. 2018; Farr and Rossman 2019; Qian et al. 1994). This is the first observation of SB on OT in Yunnan Province. OT (Nicotiana tabacum L.) is a sun-cured, highly aromatic, small-leafed variety planted under dry and hot conditions from November to April in Baoshan, where rainfall increases from February to April. SB is a major disease of OT in this area; however, it has not been reported on flue-cured tobacco in Yunnan Province. SB of OT is often misidentified as black shank caused by Phytophthora nicotianae, the most common disease on flue-cured tobacco in Yunnan Province (Zhang and Chen 1999). This report will aid local farmers and tobacco technicians in accurate diagnosis and control of the disease with more appropriate measures.

Screening of the Argentinean INTA peanut core collection with a molecular marker associated with resistance to Sclerotinia minor Jaggar

ABSTRACT Cultivated peanut, the third most important oilseed in the world, is consistently threatened by various diseases and pests. Sclerotinia minor Jagger (S. minor), the causal agent of Sclerotinia blight, is a major threat to peanut production in many countries and can reduce yield by up to 50% in severely infested fields. Host plant resistance will provide the most effective solution to managing Sclerotinia blight, but limited sources of resistance to the disease are available for use in breeding programs. Peanut germplasm collections are available for exploration and identification of new sources of resistance, but traditionally the process is lengthy, requiring years of field testing before those potential sources can be identified. Molecular markers associated with phenotypic traits can speed up the screening of germplasm accessions. The objective of this study was to genotype the peanut core collection of the Instituto Nacional de Tecnología Agropecuaria (INTA) Manfredi, Argentina, with a molecular marker associated with Sclerotinia blight resistance. One hundred and fifty-four (154) accessions from the collection were available and genotyped using the Simple Sequence Repeat (SSR) marker. Accessions from each botanical variety type represented in the core collection were identified as new potential sources of resistance and targeted for further evaluation in field tests for Sclerotinia blight resistance.

Sclerotinia minor Endornavirus 1, a Novel Pathogenicity Debilitation-Associated Mycovirus with a Wide Spectrum of Horizontal Transmissibility.

Sclerotinia minor is a phytopathogenic fungus causing sclerotinia blight on many economically important crops. Here, we have characterized the biological and molecular properties of a novel endornavirus, Sclerotinia minor endornavirus 1 (SmEV1), isolated from the hypovirulent strain LC22 of S. minor. The genome of SmEV1 is 12,626 bp long with a single, large open reading frame (ORF), coding for a putative protein of 4020 amino acids. The putative protein contains cysteine-rich region (CRR), viral methyltransferase (MTR), putative DEXDc, viral helicase (Hel), and RNA-dependent RNA polymerase (RdRp) domains. The putative protein and the conserved domains are phylogenetically related to endornaviruses. SmEV1 does not contain a site-specific nick characteristic of most previously described endornaviruses. Hypovirulence and associated traits of strain LC22 and SmEV1 were readily cotransmitted horizontally via hyphal contact to isolates of different vegetative compatibility groups of S. minor. Additionally, SmEV1 in strain LC22 was found capable of being transmitted vertically through sclerotia. Furthermore, mycelium fragments of hypovirulent strain LC22 have a protective activity against attack by S. minor. Taken together, we concluded that SmEV1 is a novel hypovirulence-associated mycovirus with a wide spectrum of transmissibility, and has potential for biological control (virocontrol) of diseases caused by S. minor.

Identifying Sclerotinia Blight Resistance in U.S. Peanut Mini‐core Collection

CSA NewsVolume 63, Issue 7 p. 14-14 Society Science Identifying Sclerotinia Blight Resistance in U.S. Peanut Mini-core Collection First published: 05 July 2018 https://doi.org/10.2134/csa2018.63.0709Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume63, Issue7July 2018Pages 14-14 RelatedInformation

Sclerotinia Blight Resistance in the US Peanut Mini‐Core Collection

Germplasm collections are valuable sources of desirable traits such as disease resistance, but many accessions have yet to be characterized. Seventy‐one accessions of the US peanut (Arachis hypogaea L.) mini‐core were evaluated from 2013 to 2015 for yield, seed quality characteristics, Sclerotinia blight (caused by Sclerotinia minor Jagger) resistance in the field, and for a Sclerotinia resistance marker. Twenty‐one accessions with <10% and six accessions with <5% disease incidence were identified from the 2 yr most favorable for disease. Resistant accessions were more likely to have a simple sequence repeat marker for Sclerotinia blight resistance, and a negative correlation between disease incidence and the presence of the resistance marker was observed. One resistant mini‐core accession, CC650 (PI 478819), was similar to commercial cultivars in yield (3617 kg ha−1 over 3 yr). CC650 also had the highest seed grade among entries at 73%, large kernels (73 g 100 seed−1), and a large proportion of extra‐large kernels. In growth chamber inoculation tests, CC650 was similar to the resistant cultivar ‘Georgia‐03L’. These results may be useful to peanut breeders seeking additional sources of resistance to Sclerotinia minor.

Genotyping of the Valencia Peanut Core Collection with a Molecular Marker Associated with Sclerotinia blight Resistance

ABSTRACT Cultivated peanut, the second most economically important legume crop throughout the United States and the third most important oilseed in the world, is consistently threatened by various diseases and pests. Sclerotinia blight, (causal agents Sclerotinia sclerotiorum (S. sclerotiorum) and Sclerotinia minor Jagger (S. minor))is a major threat to peanut production in the Southwestern U.S., Virginia, and North Carolina and can reduce yield by up to 50% in severely infested fields. S. sclerotiorum has now been reported in areas of eastern New Mexico and west Texas where all U.S. grown Valencia peanuts are produced, commonly in organic cropping environments. Host plant resistance provides the most effective solution to managing Sclerotinia blight, especially in organic systems where pesticide use is not an option for disease control. To date, no Valencia cultivars with Sclerotinia blight resistance have been released. In this study, the Valencia peanut core germplasm collection was genotyped with a Simple Sequence Repeat (SSR) marker associated with Sclerotinia blight resistance in order to identify potential germplasm for use in breeding to develop Valencia peanut cultivars resistant to the disease. Thirty accessions from the Valencia peanut core collection have profiles consistent with other genotypes that exhibit less that 5% incidence of Sclerotinia blight under heavy disease pressure. The identified accessions, after field evaluation, may serve as potential sources of Sclerotinia blight resistance in Valencia peanut breeding programs.

Characterization of Sclerotinia minor populations in Texas peanut fields

In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.

Registration of ‘Lariat’ Peanut

‘Lariat’ (Reg. No. CV‐134, PI 676980) is a high‐oleic runner‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) that has enhanced Sclerotinia blight (caused by Sclerotinia minor Jagger) resistance when compared to the cultivar Red River Runner. Lariat was released cooperatively by the USDA‐ARS and the Oklahoma Agricultural Experiment Station in 2016. Lariat (experimental designation ARSOK‐R35) is the result of a cross between cultivar Red River Runner × PI 274193 in the USDA germplasm collection. In advanced line disease trials conducted over 5 yr, Lariat averaged only 12% incidence of Sclerotinia blight, whereas Red River Runner averaged 20% and the susceptible runner‐type check cultivar Flavor Runner 458 averaged 47%. Furthermore, Lariat does not exhibit a yield boost or significant reduction in disease incidence on fungicide application, as does Red River Runner. Thus, Lariat is greatly enhanced in resistance to Sclerotinia blight compared with Red River Runner and will not require fungicide application to increase yields. Results from Oklahoma state variety trials demonstrated that Lariat is indistinguishable from Red River Runner with regards to yield and grade, thus maintaining those highly desirable traits. Production of Lariat in fields where Sclerotinia blight is present will increase profits for the grower by $200 to $500 ha−1.

Evaluation of New High Oleic Virginia-Type Peanut Cultivars for Disease Tolerance, Yield, and Quality

ABSTRACT As new cultivars are developed and released by peanut breeding programs, their levels of tolerance to common diseases and the overall profitability of production needs to be determined. Virginia-type peanut cultivars were evaluated for disease resistance/tolerance, yield, and quality when grown under different fungicide programs and in locations varying in disease pressure. Cultivars included a disease susceptible (CHAMPS) and tolerant (Bailey) cultivar and two new high-oleic cultivars, Sullivan and Wynne. Fungicide programs consisted of a leaf spot program, a leaf spot plus Cylindrocladium black rot (CBR) program, a leaf spot plus Sclerotinia blight program, or an untreated check. Cultivars and fungicide programs were arranged in a randomized split-plot design with fungicide treatments in 16-row main plots and cultivars in 4-row subplots. Disease incidence and severity varied among growing seasons and the five fields where experiments were conducted. Overall, Sullivan had good leaf spot tolerance and both Sullivan and Bailey had Sclerotinia and CBR tolerance. All cultivars yielded well in the absence of disease pressure, but Sullivan was consistently the highest yielding cultivar. Grade characteristics varied among cultivars, but while fungicide treatments impacted yield, they had little effect on grade. Net value and profitability of different fungicide programs varied by experiment, but overall Sullivan had the highest net value regardless of fungicide program. Due to slightly higher disease tolerance compared to Bailey, good agronomic characteristics, high yield and quality under a variety of growing environments, and the presence of the high-oleic trait, Sullivan is an excellent cultivar for Virginia-type peanut production in the Virginia-Carolina region.

STUDIES ON FIELD EVALUATION OF BRASSICA GERMPLASM/VARIETIES AGAINST SCLEROTINIA SCLEROTIORUM UNDER INOCULATED CONDITION

Indian mustard, Brassica juncea belong to Brassicaceae and Centre of origin Mideterian. Sclerotinia stem rot/ blight caused by Sclerotinia sclerotiorum is one of the most important fungal diseases in rapeseed and other crops in the world. The present study was undertaken to access the forty seven germplasm/varieties to find out the resistance against S. sclerotiorum under inoculated condition. The reaction of forty-seven germplasm was evaluated in randomized complete block design with thrice replications at the experimental field, Department of Plant Pathology, College of Agriculture, Gwalior during Rabi season 2014-15 and laboratory work was done in the Department of Plant Pathology, College of Agriculture, Gwalior (M.P.). Observations for severity of stem rot on main stem were recorded after 120 days of sowing using 0 - 4 scale. (Assessment scale 0-4 where 0 = no disease (resistance), 1 = less than half stem girdled (moderate resistance), 2 = more than half stem girdled (susceptible), 3 = whole stem girdled (moderate susceptible), 4 = plant dead (highly suscepitble). Forty-seven germplasm/varieties were evaluated for their reaction against Sclerotinia blight (Sclerotinia sclerotiorum). Out of forty seven germplasm / varieties, tested two Cultivar SBG-14-5 and SBG-14- 6 gave highly resistance reactions, while twenty six varieties are found resistant SBG-14-2, SBG-14-3, SBG-14-4, SBG-14-7, SBG-14-8, SBG-14-9, SBG-14-10, SBG-14-11, SBG-14-13, SBG14-15, SBG-14-17, SBG-14-18, SBG-14-23, SBG-14-27, SBG-14-28, SBG-14-30, SBG-14-31, SBG-14-32, SBG-14-33, SBG-14-34, SBG-14-35, SBG-14-36, SBG- 14-41, SBG-14-42, NDNSR-14-76, NDNSR-14-77, twelve varieties are found susceptible SBG-14-1, SBG-14-12, SBG- 14-14, SBG-14-16, SBG-14-21, SBG-14-22, SBG-14-24, SBG-14-26, SBG-14-29, SBG-14-37, SBG-14-39, SBG-14-40 and seven varieties SBG-14-19, SBG-14-20, SBG-14-25, SBG-14-38, Varuna, Rohini and BIOYSR were found highly susceptible against Sclerotinia blight (Sclerotinia sclerotiorum).

Lignin Content and Resistance to Sclerotinia minor in Peanut

ABSTRACT Lignin has been shown to be an important component for plant defense in several pathosystems, but the relationship between peanut stem lignin content and resistance in the field to Sclerotinia blight has not been investigated. Stem lignin was quantified from twenty runner, six virginia, and ten spanish genotypes grown in the greenhouse using the acetyl bromide method. Significant differences in lignin content were found within the runner and spanish entries, but not among the virginia genotypes. Disease data collected in the field over two to three years were used to test correlations between lignin content and Sclerotinia blight resistance for a subset of the runner and virginia entries. No significant correlations were found. Within the runner entries, the highest and lowest stem lignin content was found in entries with the most disease resistance. These results indicate that preformed stem lignin content is not a reliable predictor for resistance to Sclerotinia blight in peanut. In addition, commercial peanut cultivars appear to vary considerably in lignin content, and the genotypes with lower levels of stem lignin may be useful to producers who can use peanut haulm for animal feed. Southwest Runner, a cultivar with high resistance to Sclerotinia blight, had the lowest stem lignin content of the 36 peanut lines tested.

Registration of ‘VENUS’ Peanut

VENUS (Reg. No. CV‐130, PI 675157) is a large‐seeded high‐oleic virginia‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) that has enhanced Sclerotinia blight and pod rot resistance when compared to the cultivar Jupiter. VENUS is the first high‐oleic virginia peanut developed for optimal performance in the southwestern United States, and it was released cooperatively by the USDA‐ARS and the Oklahoma Agricultural Experiment Station (OAES) in 2015. VENUS (experimental designation ARSOK‐V30B) is the result of a cross between the cultivar Jupiter, a non‐high‐oleic virginia peanut released by the OAES in 2000, and ARSOK‐R2, a high‐oleic advanced runner breeding line with resistance to Sclerotinia blight. Tests conducted at three locations across Oklahoma in 2012 to 2014 showed no significant difference between the yields of VENUS and Jupiter. However, VENUS graded significantly higher than Jupiter in two out of three locations. VENUS also has better resistance to Sclerotinia blight and pod rot (61 and 70% less disease, respectively) than Jupiter. Production of VENUS peanut in areas with high Sclerotinia blight and/or pod rot disease pressures will reduce the need for fungicide applications and result in increased profits for producers.