Incidence Of Stem Rot Research Articles

Epidemiology studies of stem rot of groundnut caused by Sclerotium rolfsii Sacc in Andhra Pradesh ​​

Stem rot in groundnut is one of the major diseases significantly affecting the crop yields leading to 10 to 25 per cent yield loss annually. Favourable weather parameters influence development and spread of the disease and the present study was conducted to quantify their role in disease development. Study conducted at Banavasi village of Yemmiganur in Kurnool district, Andhra Pradesh during rabi 2020 and 2021 to know the influence of weather parameters on stem rot disease progression and the relation between leaf spot and stem rot disease development using correlation and regression analysis. A positive correlation of the stem rot with weather parameters like T max, Rainfall, Relative Humidity in rabi, 2020, Relative humidity during rabi, 2021 and negative correlation with Tmin and Wind speed in rabi, 2020, and Tmax, Tmin and rainfall in rabi, 2021 was observed. A regression analysis of the data inferred that the weather parameters as a whole contribute about 66.00% and 60.00% to disease incidence in rabi 2020 and 2021 respectively, of these Tmax (62.37%) and Rainfall (26.12%) in rabi 2020 and Tmin and rainfall during rabi, 2021. Highest stem rot incidence was recorded in 4th standard week (22nd to 28th January) with a per cent disease incidence of 6.78 during rabi, 2020 and in 52nd standard week (24th to 31st December) with a percent disease incidence of 3.6 during rabi, 2021. Initiation of leaf spot has started early i.e., 48th standard week during rabi, 2020 and 49th standard week during rabi, 2021. A non-significant positive correlation between the stem rot and leaf spot in both the years reveal that the diseases developed were solely due to influence of weather parameters on the individual disease and both the diseases are not interrelated or interdependent in causing the other.

Survey for the Incidence of Stem Rot (Sclerotium rolfsii sacc) of Groundnut in Andhra Pradesh

Background: Groundnut is an important edible leguminous oilseed crop and stem rot caused by Sclerotium rolfsii is one of the major soil borne disease affecting groundnut severely in India. The current study aimed to get an understanding regarding the incidence level and pattern of prevalence of the disease in the agro-ecological condition of Andhra Pradesh. Methods: Roving survey was taken up from major groundnut growing areas in Andhra Pradesh during kharif, 2019 and kharif, 2020 in five districts. From each district predominant groundnut growing areas were chosen for assessment of the disease. Five spots of one square meter area in each field were selected randomly and Per cent disease incidence was recorded. Result: From the data it is observed that the stem and pod rot incidence was higher during kharif, 2020 when compared with kharif, 2019. The pooled data indicated that the mean stem rot incidence for the two years ranges from 5.39% to 23.56% with highest mean stem rot incidence in Krishnapuram (v), Kothapatnam (m) of Prakasam dist (23.56%) and lowest in Bandarupalli (v), Yerpedu (m) of Chittoor dist (5.39%). Among different districts highest mean stem rot incidence was recorded in Prakasam dist (18.71%) and lowest was recorded in Chittoor dist (7.11%). The stem rot severity was high in sandy soils with TAG24 variety where groundnut is being grown followed by red sandy loams and least in clay loam soils. The groundnut sole crop recorded high disease incidence when compared with intercrop of red gram. Siginificant positive correlation was recorded between stem rot, pod rot and leaf spot incidence.

Discovering naturally-occurring microbiota in disease suppressive soil: Potential role of biological elements in suppressing Ganoderma boninense

Blenheim soil (Typic Quartzipsamment) and Bernam soil (Typic Endoaquept) with low and high Ganoderma basal stem rot (BSR) incidence, respectively, were studied to determine the role of naturally-occurring microbiota in suppressing basal stem rot (BSR) disease in oil palm. These coastal soils were also compared against a typical soil for nursery use, the inland Bungor soil (Typic Kandiudults). For each soil type, half of the soils were sterilized by autoclaving, and the other half were non-sterilized. These soils were then used for the microbiome analysis, evaluation of disease incidences, and effect on plant growth. Soil microbial communities were profiled using 16S and 18S ribosomal RNA gene amplicon sequencing on the Illumina MiSeq. Polybag trials were conducted over a period of 20 weeks. Results showed that by eliminating or inactivating the indigenous microbial communities from BSR-suppressive Blenheim soil through sterilization, this increased BSR incidences (from 50 to 92%) and severity (from 28 to 78%), and affected plant growth (reduction of 35% leaf area, 11% height, and 19% bole’s girth). Soil microbiome analysis revealed that Acidobacteriota, Nitrospirota, Latesbaciterota, Nanoarchaeota, Entotheonellaeta, Zixibacteria, Candidatus Yanofskybacteria (Patescibacteria), MB-A2-108 (Actinobacteriota), Cnidaria and Acaulospora (Mucoromycota) were less prevalent in sterilized Blenheim soil compared to non-sterilized Blenheim soil. Relative abundance of the genus Ganoderma was also lower in BSR-suppressive Blenheim soil compared to sterilized Blenheim soil. In contrast, disease development and plant growth remained unaffected by sterilization of BSR-conducive Bernam and Bungor soils, suggesting that naturally-occurring microbiota in these two soils played minimal roles in contributing to conducive conditions for disease development. Relative abundance of Ganoderma was higher in BSR-conducive Bernam and Bungor soils as well, compared to BSR-suppressive Blenheim. Results from this study provides the first insights into the soil microbiota in BSR suppressive soils and their role in BSR disease progression and growth of oil palms.

Effects of wounding and relative humidity on the incidence of Phytophthora root and stem rot in soybean seedlings

Phytophthora root and stem rot (PRSR) caused by Phytophthora sojae is a major constraint in soybean production. The effects of wounding and relative humidity (RH) on PRSR-induced damage, specifically on the mortality and infection rates in soybean seedlings, which have never been experimentally shown, were investigated. Seedlings were inoculated with P. sojae after being wounded in one of four ways (shallow, moderate, deep, or penetrative incision) or left unwounded. Immediately after inoculation, plants were subjected to five different RH treatments: 3-day wet (100% RH), 1-day wet, ambient (approximately 80% RH), 1-day dry (approximately 60% RH), and 3-day dry treatments. All wounded but uninoculated seedlings survived. The mortality rate ranged from 1 to 99% across all wounding treatments. All unwounded seedlings inoculated with the pathogen survived under all RH treatments. The mortality rates of inoculated seedlings with shallow to deep wounding increased with higher RH. The infection rate followed the same pattern as the mortality rate. Furthermore, the ratio of brown tissues in the cross section of seedlings correlated with wounding depth. These findings demonstrate that the degree of wounding is a crucial determinant of PRSR development, and high RH stimulates disease incidence.

An improvement in oilseed rape (Brassica napus L.) productivity through optimization of rice-straw quantity and plant density

• The highest yield obtained at the highest density with the most rice-straw returning. • Pod area index (PAI) increased with denser planting and more rice-straw returning. • The radiation and nitrogen use efficiency increased together with PAI. • More lignin in stem reduced the lodging risk and the incidence of sclerotinia stem rot. It was known that plant density and rice-straw returning affect the oilseed rape ( Brassica napus L.) yield in oilseed-rice rotation system. But it was not clear if their interaction influences on oilseed yield and lodging resistance. Therefore our study aimed to study role of interaction between two plant densities (D1; 45 × 10 4 plants ha −1 and D2; 75 × 10 4 plant ha −1 ) and three levels of rice-straw returning (R1; 6 × 10 3 kg ha −1 , R2; 9 × 10 3 kg ha −1 and R3, 12 × 10 3 kg ha −1 ) in improving seed yield and lodging resistance in oilseed-rice rotation system. Our results showed that the plant height and branch height increased, but the root crown diameter, branch number, pods per plant, yield per plant and lodging index decreased with the increase in plant density. Root crown diameter, branch height, pods per plant and lodging index increased while the plant height and seedling survival rate decreased due to increase in rice-straw returning. And the stem near the canopy was more prone to lodging. Low amount of rice-straw returning (R1) combined with low plant density (D1) can get high seed yield as the high seedling survival rate, while more rice-straw returning (R3) with higher plant density (D2) can elevate the seed yield by increasing the population pods and decreasing lodging index. Leaf area index (LAI), above ground nitrogen content and root nitrogen content decreased and the light transmittance (LT) increased at the bolting stage with the increase in plant density and rice-straw returning. However, the lower light transmittance (LT) associated with the increased pod area index (PAI) at the pod filling stage, which resulted in higher radiation use efficiency (RUE) and population biomass (PB). And in the pod filling stage, the above ground nitrogen content and root nitrogen content increased with the increase in rice-straw returning, but decreased with the increase in plant density, which resulted in the higher plant density and rice-straw returning, the higher nitrogen use efficiency (NUE). Besides, the activities of photosynthesis related enzymes fructose-1, 6-diphosphatase (FBP) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and the lignin synthesis related enzymes phenylalanine ammonia-lyase (PAL) and peroxidase (POD) in stem increased at the flowering stage under high plant density and large amount of rice-straw returning, resulted in increasing lignin content and decreasing incidence of sclerotinia stem rot. Present study highlights that large amount of rice-straw returning with high plant density could be used as efficient agronomic practices to improve the productivity of oilseed rape under oilseed rape-rice rotation system.

Ecology of pitaya stem rot caused by Gilbertella persicaria and its biological control by phyllosphere bacteria

AbstractGilbertella persicaria stem rot is a disease that causes rotting in the stem nodules and fruits of pitaya. Here, we aimed to study the ecology of G. persicaria and its biological control using several Bacillus subtilis strains isolated from the phyllosphere. Sporangiospores of G. persicaria were detected on different parts of the plant, with maximum density (c.239.9 propagules/cm2) found on the petals after flowering, and spore germination was observed to be considerably affected by humidity. Furthermore, the study revealed that an incision wound of at least 2 mm depth was necessary for infection by the pathogen to the stem nodule, and exposure to high temperatures (50°C) accelerated disease incidence, by disrupting resistance to the spread of the pathogen. Additionally, biological control of G. persicaria was effectively achieved by inoculation with B. subtilis strains isolated from pitaya stem nodules. Intriguingly, treatment with antagonistic bacteria reduced stem rot incidence to zero (bacterial suspension: PNB‐5, PNB‐7, and PNB‐93; culture filtrate: PNB‐7, PNB‐93, and PNB‐95), equivalent to that achieved by fungicide application in both prophylactic and simultaneous treatments. Collectively, this is the first study to demonstrate the ecology of G. persicaria and to show the potential applicability of phyllosphere bacterial strains for biological control of G. persicaria in pitaya, which could help develop effective integrated disease management strategies for the control of pitaya stem rot.

Silicon Alleviates the Disease Severity of Sclerotinia Stem Rot in Rapeseed.

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a devastating disease in rapeseed. The objective of this study was to investigate the role and the mechanism of silicon (Si) in alleviating the disease severity of S. sclerotiorum in rapeseed. In the absorption assays, the rapeseed that absorbed 10 mM of K2SiO3 exhibited an 86% decrease in lesion size on infected leaves as compared with controls. In the spray assay, the lesion length on rapeseed stems was reduced by 30.5–32.9% with the use of 100 mM of a foliar Si fertilizer as compared with controls. In the pot assay, the lesion length on rapeseed stems was reduced by 34.9–38.3% when using the Si fertilizer as basal fertilizer. In the field assay, both the disease incidence and disease index of sclerotinia stem rot were significantly reduced with the usage of a solid Si fertilizer, Si foliar fertilizer, and the application of both, without negative affection on the main agronomic traits and seed quality of rapeseed. The transcriptome sequencing, quantitative reverse transcription PCR (qRT-PCR), and biochemical assays between K2SO4- and K2SiO3- treated rapeseed leaves revealed that Si promoted the biosynthesis of defense-related substances and enhanced the antioxidation and detoxification abilities of rapeseed after infection. Thus, this study concluded that Si can alleviate the disease severity of S. sclerotiorum in rapeseeds, partially due to the induced defense responses.

Peanut disease epidemiology under dynamic microclimate conditions and management practices in North Florida.

Diverse field characteristics, weather patterns, and management practices can result in variable microclimates. The objective was to relate in-field microclimate conditions with peanut diseases and yield and determine the effect of irrigation and fungicides within these environments. Irrigation did not have a major impact on disease and yield. Stem rot (Athelia rolfsii) and early (Passalora arachidicola) and late (Nothopassalora personata) leaf spot were most affected by changes in environmental patterns across seasons. Average non-treated stem rot was 12.9% in 2017 which dropped considerably in 2018 to 0.2% but emerged again in 2019 to 3.2%. Stem rot incidence varied across the field, and the response to fungicides depended on management zone. Leaf spot defoliation in non-treated plots was severe in 2019 reaching an average of 73% at 126 days after planting but only reached 15% in 2017 and 35% in 2019 at the same stage. A low-input fungicide schedule was able to reduce foliar disease in all zones and seasons, but the microclimatic conditions in the low-lying area favored leaf spot in 2017 and 2018 although not in the dryer 2019 season. Seasonal differences in disease and plant growth affected the level of protection against average yield loss using a standard low-input program which in 2017 (527 kg/ha) was not as great as 2018 (2,235 kg/ha) or 2019 (1,763 kg/ha). Disease prediction models built on dynamic environmental factors in the context of multiple pathogens and natural field conditions could be developed to improve within-season management decisions for more efficient fungicide inputs.

Foliar fungicides and their optimum timing reduce sclerotinia stem rot incidence, improve yield and profitability in canola (Brassica napus L.)

Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (Lib.) de Bary causes significant economic losses in canola worldwide. The use of fungicides is an alternative in-field control option for SSR due to a lack of genetic resistance in commercial canola cultivars. The objectives of this study were to evaluate the efficacy and timing of foliar fungicide application for managing SSR, improving seed yield and profitability in canola. Thirteen field trials over eight years were conducted at several sites in Western Australia. In the fungicide effectiveness trials, fungicides were applied as either two-spray applications at 10 and 40% bloom or single application at 30% bloom stages. In the fungicide timing trials, fungicides were applied at various timings including 6–7 leaf, and 10, 30, 50, 60% bloom and late bloom stages. All fungicides evaluated significantly reduced the SSR incidence and improved seed yield in most years except for years of low disease pressure. Among fungicide timing treatments, the fungicides sprayed at between 10 and 50% bloom were more effective compared with earlier or later timing treatments. While both single and two spray regimes were effective, the single spray was more economical. A preliminary analysis based upon the current canola price and cost of fungicide application indicates that a yield increase of 90 kg ha−1 is required to cover the cost of a single spray regime. Yield increases greater than this were achieved in nine out of ten trials that had disease incidence above 5%.

Effect of soil solarization on viability, disease incidence and incubation period of stem rot of chrysanthemum caused by R. solani

A study conducted during 2016 at Nauni to find out the effect of soil solarization with transparent polyethylene mulch (25µm thick) was recorded on soil temperature in the earthen pots and pathogenic potential of the stem rot pathogen mixed in the soil of the earthen pots. Soil solarization increased average maximum soil temperature to 45.9 °C, in the year 2016 with an increase of 7.8 °C at 5 cm soil depth over unsolarized pots. Soil solarization for 40 days resulted in significant reduction in the potential of the pathogen to cause the disease. Soil solarization was observed on disease causing capability of the stem rot pathogen. Sclerotia of Rhizoctonia stem rot pathogen subjected to soil solarization with transparent polyethylene sheet which were put at 5 cm soil depth for 40 days lost the viability of by 88.7 per cent in comparison to unsolarized soil in the pots. Sclerotia of the stem rot pathogen subjected to soil solarization with transparent polyethylene sheet at 5 cm soil depth for 40 days increased the incubation period of the disease by 21.2 per cent i.e. symptoms were delayed and reduced the disease incidence by 46.1 per cent in comparison to unsolarized pots.

Evaluation of different dates of sowing on PDI of Sclerotinia stem rot of lentil

Pulse crops play an important role in Indian agriculture and economy and they are the major source of protein and complementary to cereals both in production and consumption. The fungus Sclerotinia sclerotiorum is one of the most destructive pathogens of lentils. Yield losses can be attributed to fungal growth within stems and resulting lodging, which leads to smaller and fewer seeds, premature ripening, shattered pods, loss of smaller, shrunken seeds during harvesting. The stem rot fungus overwinters as sclerotia in the soil, in stubble at the soil surface and mixed with seed. Sclerotia can remain viable in the field for five years or more. Each year some sclerotia will germinate when conditions are suitable but others will remain dormant. Germination is either myceliogenically which directly infect plants or may be carpogenic (spore-producing apothecia) heavy infections result from airborne spores produced by apothecia at the soil surface. The present investigation experiments were conducted to find out the effect of different dates of sowing on Sclerotinia stem rot incidence in lentil, starting form 05 October to 15 November at 10 days interval, irrespective of the year.

A Logistic Regression Model for Predicting Sclerotinia Stem Rot in Egyptian Clover (Trifolium alexandrinum L.)

Background: Stem rot caused by Sclerotinia trifoliorum is the most damaging disease of Egyptian clover (popularly called as berseem), which is widely grown as a leguminous, winter season fodder crop in India. Stem rot management currently relies on fungicides which have negative effect on livestock and environmental health. In this study, in order to rationalize the fungicide use for stem rot management, a prediction model which assesses the high risk of stem rot ( greater than 20% incidence) was developed. Methods: The disease and weather data was collected from week-50 (second week of December) to week-14 (first week of April) during 2010-11 to 2019-20. The model was developed using logistic regression modeling approach. Result: The model included increasing weekly average temperature (between 8-25oC) and wind speed (between 1-7 km/hr) as key predictor variables. Goodness of fit statistics such as number of concordant pairs (83.8%), discordant pairs (16.1%), Somers’ D (0.68), Gamma (0.68) and Tau-a (0.33) indicates high accuracy of the model. The model had high area under receiver operating characteristic curve value of 0.84 during development and 0.82 on cross validation indicating that it will perform fairly well on an independent dataset. Thus, these macro climatic-weather variables can be used to predict high risk ( greater than 20% incidence) of stem rot, which ultimately will rationalize use of fungicides for stem rot management. This is the first model to predict Sclerotinia stem rot in Egyptian clover based on weather variables in India and probably around the world.

First Report of Sclerotium hydrophilum Sace Causing Stem Rot Disease of Rice in North Eastern Plain Zone of India.

High incidence of stem rot in rice (Oryza sativa L.) caused by Sclerotium hydrophilum was observed in Eastern Gangetic plains of India including eastern Uttar Pradesh and Bihar states in rice-wheat irrigated ecosystem in the months of August and September of the years 2016-17 at the maximum tillering stage of the crop plants. A survey was conducted for the prevalence of rice diseases in Eastern Uttar Pradesh and Bihar. Stem rot incidence (12-14%) was observed in widely cultivated rice varieties viz., Swarna, Sabour Surbhit, Samba Mahsuri and Bhagalpur katarani. Brownish to black water-soaked lesions without distinct margins were visually observed on rice leaf sheaths in Pusa, Bihar and Allahabad, Uttar Pradesh (India). To isolate the causal pathogen, pieces of symptomatic leaf sheaths were treated with 1% sodium hypochlorite solution for 1 min, rinsed with sterile distilled water for 2 min, and then transferred to potato dextrose agar (PDA) medium for incubation at 280C. The cultivated mycelium was transferred to fresh PDA medium. Colonies of pure cultures on PDA medium were initially white and turned brown about 2 weeks later. The hyphal width was measured with a range of 4.0 to 6.0 μm. Large numbers of small globose sclerotia were observed on surface of the colonies at 5 days after sub-culturing. The sclerotia were white at first and then turned black over time with maturity. The diameters of sclerotia ranged from 0.32 to 0.51 mm with an average of 0.41 mm (n = 50). DNA of a representative isolate named SH1 was extracted, and the ITS region was amplified by PCR with universal primer pair ITS1/ITS4 (White et al. 1990). Sequence analysis showed 99.66% identity with Sclerotium hydrophilum isolate VC228 (accession no. KT362098) and accession no. obtained (KX181457). Phylogenetic analysis based onneighbour-joining method grouped the isolatesalongwith other isolates from Asia. The pathogen was identified as Sclerotium hydrophilum on the basis of cultural, morphological, pathogenic and molecular characteristics. Further, culture was deposited to Indian Type Culture Collection (ITCC) at the Indian Agricultural Research Institute, New Delhi for the identification where it was identified as Sclerotium hydrophilum with identification number 10039.15. Another culture specimen of the pathogen was also deposited at the ITCC-IARI, New Delhi with accession no. 19160.25. Koch's postulates were completed by inoculating rice plants with PDA disks of5 mm in size bearing both mycelium and sclerotia of S. hydrophilum in 45 days old plants of rice genotype 'Samba Mahsuri' under glass house conditions. After 4th days leaf sheath necrosis was observed around the inoculation plugsunder field conditions.The same fungus was re isolated from the symptomatic lesions of inoculated plants, fulfilling Koch's postulates. Pathogen was reported with high disease incidence in Northern Karnataka (Pramesh et al. 2017). However, based on literature and fungus-host distribution records this is the first report of S. hydrophilum on leaf sheath of rice from North-Eastern plain zone of India.

Factors influencing the incidence of basal stem rot and blight disease caused by Sclerotium rolfsii in vegetable cowpea and its management using botanicals

Basal stem rot and blight disease incited by Sclerotium rolfsii resulted in significant crop loss in vegetable cowpea. Among the different levels of pH tested under in vitro conditions, pH 6.0 was revealed to be optimum for the mycelial growth, whereas pH 7.0 supported maximum sclerotia formation. Soil moisture of 35 to 50 per cent was ideal for early disease expression and establishment. A minimum level of two per cent fungal inoculum multiplied in sand oats medium resulted in complete disease incidence. Among the botanicals tested in vitro, garlic bulb extract (1%) and garlic creeper leaf extract (5%) revealed cent per cent inhibition of mycelial growth and sclerotia formation of the fungus. Both the extracts also inhibited the mycelial regeneration from sclerotia. Thus, garlic bulb and garlic creeper were revealed to be potent botanicals which can be used as effective alternatives to soil fumigants for the management of S. rolfsii .

Geostatistics of Oil Palm Trees Affected by Ganoderma Disease in Low and High Planting Density

This study was conducted to assess the influence of two oil palm planting density (PD) on the incidence and severity of the Ganoderma basal stem rot (BSR) disease in oil palm planted in a plantation at Bagan Datuk, Perak, Malaysia. Ground surveys were conducted in oil palm planted in two planting densities involved which are: 120 palms/ha (lowest PD) and 200 palms/ha (highest PD) to assess the incidence and severity of BSR disease in oil palm plantations, over the 25 years after planting, YAP. The presence of the BSR disease symptoms as visually assigned followed the Standard Operating Procedures (SOP) Guidelines for Managing Ganoderma Disease in Oil Palm. Semivariogram analysis was performed on the data to show the spatiotemporal structure of BSR disease at 10, 15, 20 and 25 years after planting. The disease incidence was observed in all both plots with 0.57% to 1.67% at 8 years after planting, followed by increased to 15.12% to 38.3% at 16 years after planting. At 25 years, high BSR disease incidence was recorded on 200 palms/ha (72.5%), whilst low BSR disease incidence was recorded on 120 palm/ha. Effects of nugget to sill were found relatively moderate to weak of spatial pattern distribution. The observed disease patterns suggest that the progress of BSR disease incidence is firstly randomly scattered (8 to 10 years after planting) and secondly by root-to-root contact of the disease spreading to neighbouring palms may be occurred. Further study is needed to investigate factors associated with the outbreak of BSR disease in these plantations.

Evaluation of in vitro antagonistic activity of fungi from peatlands against Ganoderma species under acidic condition

Abstract. Supriyanto, Purwanto, Poromarto SH, Supyani. 2020. Evaluation of in vitro antagonistic activity of fungi from peatlands against Ganoderma species under acidic conditions. Biodiversitas 21: 2935-2945. The use of peatlands is a significant contributor to the world’s palm oil production. A serious problem of oil palm plantations in peatlands is the high incidence of basal stem rot (BSR) disease caused by Ganoderma, which has a higher attack rate than on mineral soils. There is no effective way to control Ganoderma in peatlands. At present, the effort for the same focuses on environment-friendly biological methods; however, this is constrained by the unavailability of appropriate biological agents for peatlands. The development of biological control agents for peatlands is hampered by limited data on biological control of Ganoderma in peatlands. This research was conducted to evaluate the in vitro antagonistic activity of fungi isolated from a peatland in acidic pH conditions. Twenty-seven Ganoderma-antagonistic fungi from peatland were evaluated for their activity and their ability to antagonism in vitro within a pH range of 2-7. The results show that most antagonistic fungi from peatland, based on biomass weight, the sporulation ability, and germination of conidium, were able to grow optimally at pH 3.0-4.0, indicating that most of the Ganoderma-antagonistic fungi from peatland can be used as biological control agents for BSR on oil palms in peatlands.

Standardization of inoculation technique to identify the sources of resistance against stem and pod rot of groundnut

A technique was standardized to screen for resistance to stem rot ( Sclerotium rolfsii Sacc.) in groundnut ( Arachis hypogaea L.). A total of seven different inoculation techniques were screened by using susceptible genotype TMV-2. The techniques involved inoculation of 10 day old groundnut plants raised in pots by spreading mycelial propagules of S. rolfsii grown on sorghum grain medium (SGM) on soil surface, Inoculum spread on the soil surface and covered with groundnut leaf debris, Inoculum placed around the collar region, Inoculum placed around the collar region and covered with groundnut leaf debris, Inoculum mixed in the soil, Inoculum mixed in the soil and covered with groundnut leaf debris, Agar disc method. Among these techniques inoculum spread on the soil surface and covered with groundnut leaf debris was found to be most efficient in getting highest per cent incidence of stem rot (84.86%) and pod rot (70.48%).

GG 41: A high yielding Virginia runner groundnut (Arachis hypogaea L.) variety for Gujarat state

A Virginia runner groundnut Variety GG 41 was developed from the cross GG 21 and TPG 41. This genotypewas tested at multilocation from 2014 to 2018 during kharif season in Gujarat. It recorded a high mean pod yield of 2722 kg/ha as compared to the checks viz., GG 11 (2352 kg/ha) and GJG 17 (2344 kg/ha). Pod yield superiority of this variety over the checks, GG 11 and GJG 17 were 15.74% and 16.10%. Average kernel yield of GG 41 was 2010 kg/ha as against the checks GG 11 (1586 kg/ha) and GJG 17 (1596 kg/ha). Mean 100-kernel weight of GG 41 was 56.48 g; 100-pod weight was 144.98 g; shelling out-turn was 73.84% and the average oil content was 51.44%.Incidence of stem rot and collar rot of the variety was very low as compared to the check varieties. The damage due to leaf defoliators and thrips under field conditions was lower in GG 41 as compared to the check varieties. Based on the superior performance, this genotype has been released in 15th Combined Joint AGRESCO Committee of SAUs of Gujarat as GG 41 for general cultivation in the kharif rainfed spreading variety groundnut growing areas of the Gujarat State.

Management of groundnut diseases through organic amendments, bio products and biocontrol agents

Field experiments were conducted at the Main Oilseeds Research Station, Junagadh Agricultural university,Junagadh (Gujarat) during kharif for three consecutive seasons to evaluate the efficacy of application of organicamendments enriched with biological control agents and application of biological control agents and bio-product as foliar spray in managing soil borne as well as foliar diseases of groundnut. Pooled analysis of the data of three years revealed that the management of collar rot (1.80 %) and stem rot incidence (1.52%) was obtained in the treatment where Trichoderma harzianum was used as a seed treatment@ 10 g/kg seed along with its furrow application @ 4 kg enriched in FYM @ 300 kg/ha at the time of sowing.

Integrated management of major diseases of sesame (Sesamum indicum L.)

Among fungal diseases, stem and root rot, Alternaria leaf spot and Cercospora leaf spot were become major constraints for cultivation of sesame in South 24-Parganas district of West Bengal, India. Considering the fact, the following investigation was carried out for this pathological problem. Field trials conducted on integrated disease management practices to combat major diseases and to increase the seed yield of sesame during summer, 2018 and 2019. Minimum incidence of stem and root rot (8.8% and 11.2%) with higher yield of 527 kg/ha and 577 kg/ha were recorded in summer, 2018 and 2019 with application of organic amendment with FYM and neem cake @ 150 kg/ha (1:1, T4). In case of foliar diseases of sesame, applications of FYM + NPK @ 60:30:30 (1:1, T3) was found to be significantly effective by recording minimum incidence of Alternaria leaf spot (6.3% and 8.4%) and Cercospora leaf spot (4.2% and 5.3%) coupled with maximum yield (512 kg/ha and 541 kg/ha) with higher cost benefit (C:B) ratio in summer, 2018 and 2019.