Powdery mildew (PM) caused by Erysiphie pisi Syd. is the most devastating disease of pea, affecting fresh pea production as well as the quality of the marketable harvest worldwide. The efforts were made to develop PM-resistant mutants of popular pea varieties “Lincoln” and “Azad P-1” through induced mutations by following gamma irradiation (300, 400, 500, and 600 Gy) and chemical mutagenesis, i.e., ethyl methane sulfonate (EMS) (0.3% and 0.4%). The screening of 13,868 M2 progenies at Kukumseri (summer season) followed by M3 generation at Palampur (winter season) resulted in the isolation of six putative PM-resistant mutants. The rigorous evaluation of these progenies under in vivo (field screening) and in vitro (artificial screening under greenhouse conditions and using the detached leaf assay method) conditions over the years resulted in the isolation of three PM-resistant mutants, viz., L-40-1014, L-0.3-139, and AP-0.3-129. SSR markers “PSMPSAD60 d” and “PSMPA5 c” linked to the er-1 gene indicated the presence of the “er1” gene in the mutant L-0.3-139 while the er-2 gene-linked SCAR marker “ScX171400” and SSR marker “AD141” indicated the probability of the “er-2” gene in mutant L-40-1014. The known markers linked to PM resistance genes could not be validated in the mutant AP-0.3-129, suggested to identify new markers linked to PM resistance. These PM-resistant mutants can be promising candidates as the new source of resistance for future pea breeding programs.

Powdery mildew is one of the serious diseases of garden pea which causes a large number of yield losses. Genetic resistance is quite effective, being cost-effective and environment friendly than fungicide applications. In the present studies an initial attempt has been made to identify resistant genotypes against powdery mildew disease developed from hybridization followed by validation of the disease. The experimental material comprised of 48 genotypes that includes 44 advanced breeding lines was evaluated for powdery mildew incidence in Randomized Complete Block Design with three replications at two locations under field conditions [Palampur (winter 2017–18 and 2018–19) and Kukumseri (summer 2018)] and in vitro at Palampur [detached leaf method and polyhouse conditions]. Ten lines viz., SP7, SN-1, SN-6-1, SN-7-1, SN-2, SN-5-2, SN-6-2, SN-10, SN-21 and SP-281 showed resistant reaction along with check Palam Sumool while 27 lines were identified as moderately resistant in comparison to susceptible check Azad P-1. Besides, six lines namely, SP-2, SP-5, SP-10, SP-24, SA-4 and SP-12-1 gave moderately susceptible reaction along with checks Pb-89 and Palam Priya. Only, SP-19 was categorized as susceptible. The high yielding lines SP-3, SP-6 and SP-22 showed moderately resistant reaction in both natural and artificial conditions. Validation of resistance using molecular markers revealed that neither the parental genotypes nor the progenies possess the er1 gene of JI1559. The er2 linked marker ScOPX-17 1700 was polymorphic between Palam Sumool and Palam Priya but the marker didn’t show polymorphism between er2 harboring line (JI2480). These results suggested that the lines showing resistance under field conditions may have some other genes or alleles for resistance and further confirmation is needed by developing mapping populations with specific gene or gene combinations.

Blast caused by Magnaporthe grisea has emerged as a major threat in recent years to forage pearl millet in India. Due to lack of resistant cultivars to blast disease, the disease can be best managed through fungicides. However, no comprehensive multi-location study in managing blast disease in forage pearl millet has been conducted in India. Therefore, field trials for two consecutive years (2019 and 2020) were conducted at four geographically different locations (Ludhiana, Palampur, Jhansi and Bhubaneswar) of India. Carbendazim, tebuconazole + trifloxystrobin, tricyclazole, chitosan and neem oil were tested for their efficacy through seed treatment alone or seed treatment followed by two foliar sprays at 15 days interval. Results showed the superiority of tebuconazole + trifloxystrobin as seed treatment followed by two foliar sprays in reducing the blast disease area under disease progress as well as rate of infection at Ludhiana, Jhansi and Palampur. Tricyclazole as seed treatment followed by two foliar sprays was found superior over others in reducing the area under disease progress curve as well as rate of infection at Bhubaneswar. Reduction in blast disease area under disease progress curve and rate of infection by applying these treatments helped in achieving a significant increase in the green fodder yield at the tested locations. Through this study, an effective strategy for location specific management of blast disease of forage pearl millet has been formulated.

Red clover (Trifolium pratense L.) is an important leguminous forage crop of temperate regions throughout the world including India. Red clover suffers serious seed yield losses due to crown rot (caused by Sclerotinia trifoliorum) and powdery mildew (caused by Erysiphe trifoliorum) diseases. Resistant varieties against these two devastating diseases are not available, which necessitates the development of alternate management strategies for these diseases. In order to develop alternate management strategies for these diseases, this study was conducted during 2013-14 to 2017-18 at Palampur (India). Three fungicides (carbendazim, wettable sulphur, hexaconazole) and one biocontrol agent (Trichoderma viride) were tested in different combinations for combined management of these diseases. Results from five year study indicates that seed treatment with carbendazim followed by three foliar sprays of hexaconazole and seed treatment with carbendazim followed by one foliar spray each of T. viride, wettable sulphur and hexaconazole at 10 days interval can effectively control powdery mildew and crown rot diseases, respectively. Applications of these treatments showed significant superiority over others by not only reducing disease severity but also resulted in higher seed yield. Thus, these management strategies can be effectively deployed for simultaneous management of two most serious diseases in red clover.

The present investigation was undertaken to assess the extent of genetic variability and diversity among different oat genotypes using agro-morphological and molecular markers. Data were recorded on agro-morphological, quality traits and reaction to powdery mildew resistance on 57 oat genotypes. Genetic diversity among different genotypes was studied based on morphological traits using Mahalanobis D-2-statistic, principal component analysis (PCA) and SSR markers. Phenotypic coefficient of variance (PCV), genotypic coefficient of variation (GCV) and heritability was found high for several economically important yield-related traits. Based on D-2-statistic, all the genotypes were grouped into eight clusters. Consequently, SSR analysis grouped the genotypes into two main clusters which were further divided into two sub-clusters. The selected panel of forty-seven SSR primers was able to identify a total of 171 alleles. Polymorphism information content (PIC) ranged from 0.30 to 0.68 with an average value of 0.502. Present findings demonstrated that overall, there were sufficient variability in the breeding materials indicating that selection would be effective in future hybridization programme and the diverse genotypes could be used as parents to generate transgressive segregants.

Powdery mildew (caused by Blumeria graminis DC. f. sp. avenae Em. Marchal) is the most important disease of common oat (Avena sativa L.) in cooler and humid regions of the world including India. In spite of this, no prediction model for assessing the high risk (>30% severity) of powdery mildew in common oat is available. In the present study, a logistic regression model which assesses the high risk of powdery mildew in common oat was developed using weather and disease data collected from 15 years (2004-05 to 2018-19) observations in a monitoring experiment conducted at Palampur, India. The model incorporated increasing weekly average temperature (between 11.5 and 21.9 degrees C) coupled with decreasing relative humidity (between 40 and 60%) and sunshine (between 5.4 and 8.7 h) as key predictors for high (>30% severity) powdery mildew severity. The model was validated for its accuracy using cross validation technique with area under receiver operating characteristic curve value (AUC) of 0.89 during development and 0.87 on cross validation. Since the model depends on weekly values of commonly available macro-climatic weather variables, the fungicide spraying can be done in advance which will help in reducing the losses caused by powdery mildew of common oat. To our knowledge, this is the first model for predicting powdery mildew disease of common oat in India and probably around the world.

Bacterial wilt of solanaceous vegetables caused by the soil-borne pathogen Ralstonia solanacearum is a serious plant disease-causing heavy economical losses. Traditional methods such as vegetable grafting, cultural, biological, and chemical methods have limited success rate against bacterial wilt when used alone though in combination some success has been reported. Biotechnological techniques such as somatic hybridization/protoplast fusion, marker-assisted breeding, genetic engineering, transcriptomics, and gene silencing against bacterial wilt disease are the techniques which may circumvent problems associated with selection for disease resistance with the use of conventional breeding. There is a need for cultivars with stable resistance. In this review, information regarding somatic hybridization, marker-assisted breeding, transcriptomics, genetic engineering and gene silencing so far accomplished in the solanaceous vegetables to combat the bacterial wilt has been covered.

Zonate leaf spot (caused by Gloeocercospora sorghi Bain and Edgerton) is the most serious foliar disease in forage sorghum. Disease is currently managed through fungicide applications without any pre-informed decision-making. Prediction models which can help in decision-making regarding fungicide use for zonate leaf spot management are lacking. In this study, we model the relationship between weather conditions and zonate leaf spot to develop a decision support system for disease management. Zonate leaf spot severity on rainy season (last week of June to third week of October) sorghum was recorded during 2010–2020 on susceptible cultivar SL-44 in a monitoring experiment conducted at humid, subtropical location (Ludhiana, India). Window pane analysis resulted in identification of weekly average minimum temperature (Tmin), average temperature (Tav), and afternoon relative humidity (RHa) as potential predictors of zonate leaf spot. Regression models based on Tmin, Tmin + RHa, and Tav + RHa were able to explain 56, 56, and 54% variation in disease severity respectively at the tested location. These three models were also validated for accuracy in hot, semi-humid (at Jhansi on cultivar MP Chari), and sub-humid climatic (at Palampur on cultivar Kanchan) conditions. Model based on Tmin + RHa explained 59% variation in disease severity at Jhansi. At Palampur, models based on Tmin + RHa and Tav + RHa were able to explain 59% variation in disease severity. As the models performed well in different climatic situations, they could be used for risk assessment of zonate leaf spot epidemics in sorghum.