Cent Disease Severity Research Articles

Screening Taro Germplasm against Bacterial Blight Incited by Xanthomonas axonopodis pv. dieffenbachia

Sixty-four Taro germplasm accessions from north east India along with two national released varieties were evaluated in natural epiphytotic field condition against bacterial blight incited by Xanthomonas axonopodis pv. dieffenbachia for two consecutive seasons during 2018 and 2019 at an Experimental Farm for Horticultural crops, Assam Agricultural University, Jorhat. The results obtained for the two growing seasons were pooled together. Per cent disease incidence and disease severity ranged from 23.81 (Nepali-2) to 78.57 % (SC-1) and 14.17 (Nepali-2) to 67.50 % (SC-1) respectively. The area under the disease progress curve (AUDPC) which directly corresponds to the bacterial disease infection with time resulting in more susceptibility to the disease ranged from 1612.5 (Sreekiran) to 9812.5 (SC-1). AUDPC was calculated from the per cent disease severity obtained from the first day of disease observation till the last day i.e. from 60 to 240 days after transplanting (DAT). The disease reactions of different germplasm to bacterial blight of colocasia were evaluated based on the disease severity (%) and disease rating scale whereby no cultivars were immune and highly susceptible to the disease. Four accessions viz. Sreekiran, Naga-2, Chandil Pin, Nepali-2 were resistant, twenty-one were moderately resistant, twenty-six were moderately susceptible and fifteen were susceptible. Variety/germplasm resistant to bacterial blight of Taro have not been reported till date. Proper selection of resistant varieties will be useful in breeding programmes and for further crop improvement.

Identification and confirmation of powdery mildew (Erysiphe polygoni) resistance in pea germplasm

Erysiphe polygoni DC, the causative agent of powdery mildew, poses a significant threat to pea crop, resulting in substantial yield and economic losses. To address this menace, an exploration of intrinsic resistance within pea germplasm becomes imperative for effective disease management. In our study, phenotyping of 1095 pea accessions, sourced from both indigenous and exotic origins, under natural epiphytotic conditions during Rabi 2021-22, revealed a prevailing susceptibility, with over 60 per cent disease severity in majority of accessions. Remarkably, only 22 accessions, including IC208327, IC220109, IC220378, IC258401, IC262762, IC262849, IC267140, IC267174, IC267727, IC274039, IC274040, IC310074, IC311066, IC345548, IC424898, IC552779, IC613133, IC629544, IC629687, NC57793, IC220193 and EC598669, exhibited resistance with a disease score of <1. Subsequent, pot screening of these 22 resistant accessions under artificial epiphytotic conditions during Rabi 2022-23 confirmed their resistance showing disease severity ranging from 5.83 - 17.50 per cent. Recognizing the pivotal role of resistant varieties in disease management, these identified accessions hold immense potential as resistant donors in crop improvement programs.. KEYWORDS :Germplasm, pea, powdery mildew, resistance

Bioprospecting of citrus (Citrus L.) germplasms against citrus canker pathogenesis in Assam, North‐East India

AbstractThe current investigation assessed the effectiveness of 30 citrus germplasms in combating citrus canker pathogenesis in Assam, North‐East India. Significant differences were observed among the examined citrus germplasms in terms of per cent disease severity and disease reduction against Xanthomonas citri pv. citri. Among the 30 different germplasms, eight germplasms, namely, Jora tenga (14.67%), Bonjora (15.58%), Holong tenga (15.75%), Latipes (17.34%), Patijora (17.75%), Birajora (18.50%), Cleopatra mandarin (20.00%) and Ada jamir (20.18%), exhibited highest disease resistance potential. The study recorded that the germplasm Latipes, which are resistant, had the highest total phenol content (21.26 mg/g dry weight), while the susceptible one, Grapefruit (7.85 mg/g dry weight), had the lowest total phenol content. Jora tenga exhibited the highest flavonoid content, measuring at 6.48 mg/g dry weight, whereas White pummelo had the lowest flavonoid content, measuring at 1.88 mg/g dry weight. Similarly, the highest alkaloid percentage was recorded in resistant germplasm, Adajamir (10.52%), while the lowest was in susceptible germplasm, Volkameriana (2.30%). The levels of total phenol, alkaloid and flavonoid contents exhibited a significant negative correlation with the per cent disease severity of citrus canker disease in both Pearson correlation and Spearmen correlation analysis. The current research on bioprospecting of citrus germplasms in relation to citrus canker pathogenesis has the potential to offer valuable insights into mitigating the transmission of bacterial pathogens and eliminating sources of infection by employing resistant cultivars and implementing approved doses of plant protection formulations.

Influence of soil parameters and planting depth on black scurf development in Potato

Solanum tuberosum is an important vegetable crop worldwide. Among various diseases, black scurf disease caused by Rhizoctonia solani Kuhnh as emerged as a major problem and is known to cause qualitative and quantitative losses in potato.The management of R. solani causing black scurf is complex due to its soilborne nature and high level of survival and poses a challenge for the eco-friendly management of the disease. The existing fungicides control measures are neither economical nor environment friendly; therefore sustainable effective disease management strategy is required. Available information on management of black scurf (R. solani) disease is scanty. The present investigation was carried out in the Agricultural Research farm (Vegetable Science), Guru Kashi University, Talwandi Sabo during rabi seasons, 2021-22 and 2022- 23.The ‘Kufri Pukhraj’ infected potato tubers were planted during 15th November in both respective years under field conditions with three replications at different depth of planting (soil depth: 15, 20 and 25 cm). Results revealed that per cent disease incidence and severity increased with increase in depth of planting during both the years. Black scurf incidence and severity showed a positive correlation with morning soil temperature and soil moisture whereas, a negative correlation with evening soil temperature (STe). The optimization in depth of planting can be a good eco-friendly and economic alternative for the management of black scurf of potato.

Management of Bacterial Blight of Clusterbean Caused by Xanthomonas axonopodis pv. cyamopsidis under Field Conditions

Background: Bacterial blight pathogen (Xanthomonas axonopodis pv. cyamopsidis) of clusterbean causes considerable damage every year during Kharif season and sometimes become very severe, which results in heavy loss in grain yield. Methods: On the basis of in vitro studies, most effective botanical, antibiotic and fungicide at highest concentration were used as individual and its combinations in field experiment during two consecutive years Kharif 2018 and 2019. Seeds of clusterbean cultivar RGC-936 were artificially inoculated with X. axonopodis pv. cyamopsidis by soaking in bacterial cell suspension (2.5x108 cfu/ml) for 30 min and dried under shade. The artificially inoculated seeds were used for sowing in field trial Result: Field evaluation, the combined treatment, seed treatment with streptocycline @ 250 ppm followed two foliar sprays of streptocycline @ 250 ppm and 1st foliar spray of copper oxychloride @ 0.3 per cent and 2nd foliar spray of streptocycline @ 250 ppm at 15 days interval was found the most effective in reducing the per cent disease severity and increasing the grain and fodder yield in clusterbean.

Survey, Occurrence of Major Onion Diseases and Management of Twister Disease of Onion (Allium cepa L.)

Purple blotch of onion caused by the fungus Alternaria porri is a serious disease in kharif season and more yield losses in onion growing areas of Maharashtra. A survey was conducted to assess disease intensity of major diseases in onion growing area in Nashik district during kharif 2020 and 2021 During the survey, small whitish, leaf curling, twisting, chlorosis of leaves, elongation of neck and cylindrical bulb such symptoms of twister disease were observed more severe than purple blotch on onion in kharif 2020. The per cent disease severity ranged from 17.28 to 45.83 per cent and 8.00 to 23.00 per cent in purple blotch of onion and 20.17 to 54.59 per cent and 12.00 to 35.00 per cent twister disease of onion during kharif 2020 and 2021, respectively. The diseased samples were utilized for isolation of pathogen. After isolation and morphological study, it is indicated that twister disease of onion was complex of pathogen caused by Colletotrichum gloeosporioides, Fusarium sp. and nematode. Due to climate change, from the survey concluded that twister disease was found more serious and threatening disease than purple blotch of onion during kharif 2020 and 2021. Considering the yield losses caused by twister disease of onion, the investigation was planned for management of twister disease during kharif 21. The combine application of Trichoderma drenching @ 10 g/l along with two alternate sprays of each Tebuconazole 25.9 EC @ 1 ml/l or Azoxystrobin 23 SC@ 1 ml/l recorded lowest PDI of twister disease (14.33%) of onion than the control treatment (49.11%) and which was found effective maximum per cent disease over control (70.82%) for management of twister disease of onion.

Identification of Rich Oil-Protein and Disease Resistance Genotypes in Soybean [Glycine max (L.) Merrill

A study was undertaken on oil-protein content and their relation with yield and evaluation of resistance for aerial blight and frog eye leaf spot diseases in soybean during kharif (July−December, 2019) at J.N.K.V.V., Jabalpur, Madhya Pradesh, India. The experiment was laid out using augmented block design with 154 genotypes of soybean including four check varieties namely JS 20-34, JS 20-98, JS 335 and NRC 86. Per cent disease severity was measured at peak of disease during seed formation stage (R5-R6). Yield and 100 seed weight were recorded at time of harvesting. Oil and protein content from harvested yield was estimated by using standard methods of association of official analytical chemists (AOAC). The results revealed that oil content varied from 16.8−20.2% and protein content from 36.1−41.2% in all 154 genotypes. Per plant average seed yield (3.9-15.1 g) and hundred seed weight (6.7−14.7 g) were also varied from genotypes to genotypes. The correlation between oil and protein was highly negative (r=-0.620**, p=0.01). This investigation identified ten genotypes with high oil (>20%) and fourteen genotypes with high protein (>40%) content. Among which JS 20-104, Cat 473B and RKS 24 were higher in protein, and Cat 48, Cat 330 and JS 20−69 were higher in oil content. In disease evaluation, eleven genotypes namely Cat 473B, Cat 60, Cat 642, JS 20−76, JSM 122, JSM 126A, JSM 126B, JSM 203, JSM 287, RKS 66 and SQL 89 exhibited dual resistance for aerial blight as well as frog eye leaf spot were screened out. The result showed that variation in oil-protein content and disease resistance depends on the genotype.

Screening of Exotic Collections of Arabica Coffee Genotypes for Coffee Berry Borer and Coffee Leaf Rust Disease Incidence

In India, commercial cultivation of coffee relies upon two important species like Coffea arabica (Arabica coffee) and Coffea canephora (Robusta coffee). In the consumer market, arabica coffee is preferred for its fine beverage quality, aromatic characteristics and low caffeine content compared to robusta coffee. In India coffee is grown under natural agroecosystem offers arabica coffee to fetch premium price in the international market. In spite of the commercial importance and the appropriate environmental conditions, the drastic reduction of arabica coffee area in India is likely associated with lack of adaptability for each ecological zone of the region, susceptibility to coffee berry borer and leaf rust and increased cost of production coupled with low productivity (470 kg clean coffee/ha). Therefore to address the issues identification of resistance source is the important criteria in crop improvement programme. With this background the study was aimed at screening of exotic collections of Arabica coffee genotypes maintained at Central Coffee Research Institute (CCRI), Balehonnur, Karnataka, India against Coffee Berry Borer (CBB) and Coffee Leaf Rust (CLR). The experiment was laid out randomized block design with three replications. Results revealed that, the CLR disease severity infection was ranged from 1.34 to 32.67 per cent and the genotypes S.1495, S.1561, S.2504, S.2509, S.2510, S.2529, S.2602 and S.2724 exhibited moderately resistant to leaf rust disease infection based on mean per cent disease severity level (1-5%). Hence, these genotypes will be valuable as new sources of resistance to these pathogens in the future and can be utilized in coffee breeding programmes in India. Similarly, all the genotypes utilized in the study were established low to least infestation of coffee berry borer (1.03 to 5.03 %).

Symptomatology of Sigatoka leaf spot disease in banana landraces and identification of its pathogen as Mycosphaerella eumusae

Mycosphaerella musicola, M. fijiensis and M. eumusae are known to cause banana yellow Sigatoka, black Sigatoka and Eumusae leaf spot diseases respectively. However, differentiating the causative species has been challenging and the responses of banana landraces to this pathogen were little known. Purposive sampling surveys were conducted in different agro-climatic zones of Kerala state, India, to collect the leaf samples with Sigatoka leaf spot-like symptoms, to document the symptom expression on different landraces and to confirm the identity of the pathogen at species level. Fields surveyed during the post-monsoon period had 100% disease incidence with highest per cent disease severity of 43.90% in nine-month old cv. Palayankodan, while lowest PDS of 3.33% was observed in three-month old cv. Njalipoovan, during a pre-monsoon survey. Initial symptoms were small brown streaks, later developing into oval or elliptical brown spots with greyish centre and subsequently coalescing for leaf necrosis. Symptoms in different landraces varied across the zones. Sequencing and analysis of the ITS region from 50 isolates collected during the survey showed 99–100% homology with M. eumusae . Phylogenetic analyses further proved the species identity of the local isolates. Comparing the ITS barcodes of the three species of Mycosphaerella along with the local isolates confirmed that the pathogen inciting Sigatoka leaf spot in Kerala state, India, is Mycosphaerella eumusae .

Role of Weather Parameters on Development of Early Blight of Tomato Caused by Alternaria solani

The field experiment as conducted to study on the influence of weather parameters on the intensity and development of early blight of tomato during , 2018-19 and 2019-20 at Agriculture Research Station, Gunjevu, Holenarasipur taluk, Hassan district. The Rabi epidemiological studies clearly revealed that per cent disease index (PDI) progressing at a linear rate as the growth of the plant advances and weather parameters like minimum temperature, evening relative humidity, morning relative humidity rainfall, number of rainy days found significant and in negative correlation with disease development. The multiple linear regression analysis clearly revealed that coefficient of multiple determinants (R ) was 0.94 indicating that these weather factors responsible up to an extent of 94.00 per cent for early blight disease 2 development. The regression equation also reveals that increase in 1 per cent of morning relative humidity the PDI increased by 0.446%. While, when there was increase in 1° C of minimum temperature the per cent disease severity decreased by 12.606 per cent.

Waxy bloom on capsules is a major determinant of early infection by gray mold (Amphobotrys ricini(N.F. Buchw.) Hennebert) in castor (Ricinus communisL.)

AbstractGray mold is a major disease of castor caused by the pathogenAmphobotrys ricini. It mainly affects the inflorescence resulting in severe yield losses. Role of qualitative characters of inflorescence (spike) and capsuleviz. spike compactness, capsule type, waxy bloom intensity on capsules (visual), capsule spine length, spine texture and spine density in predisposing castor crop to gray mold was investigated. A set of 26 castor lines differing for presence and intensity of bloom was characterized for spike and capsule characters. The lines were screened in vitro (detached spike and capsule techniques) and in vivo by raising the plants in poly house and field conditions for disease reaction. Spearman's rank correlation analysis revealed significant positive correlation (rs = >0.5;p = <0.05) between disease severity and capsule type, capsule waxy bloom, spine texture, spine length. Principal component regression analysis revealed that waxy bloom intensity is the major factor, among the evaluated, that predisposes castor lines to the fungus infection promoting disease severity. Quantification of epicuticular wax from capsules of different waxy bloom lines revealed that there was an increase in severity of infection with increase in wax quantity on capsules irrespective of nature of bloom substantiating the role of waxy bloom quantity in promoting the infection. High quantities of wax (1.50–3.00 µg/mg) were extracted from lines showing high per cent disease severity (40%–95%), and low quantities of wax (0.00–1.50 µg/mg) were extracted from lines showing low per cent disease severity (1%–40%). A disease scoring scale considering differences in waxy bloom quantity as a biochemical marker has been proposed. It may not be a replacement to phenotypic screenings but helps breeders in selecting early generation material for low disease severity when huge populations are to be screened against gray mold by choosing low waxy bloom varieties.

Effect of plant extracts against stripe rust of barley caused by Puccinia striiformis f. sp. hordei

Effect of plants leaf extracts, i.e. Garlic, Oak, Neem, Dathura, Partheneium, Tulsi, Castor and Ashwagandha were studied at four different concentrations (3, 5, 10 and 15 %). Barley stripe rust disease was tested on susceptible barley cultivar RD 2035 under artificial rust inoculation conditions during two consecutive Rabi, seasons 2016-17 and 2017-18 in cage house. All concentration of eight plants leaf extracts increased per cent disease suppression and decrease the per cent disease severity, than in the control. Among these extracts garlic clove extract proved as best with highest per cent disease suppression (53.10) and significantly low mean per cent rust severity (39.78) followed by leaf extracts of neem (Azadirachta indica), tulshi (Ocimum tenuiflorum), datura (Datura stramonium), oak (Calotropics gigantean), partheneium (Parthenium hysterophorus), castor (Ricinus communis) and ashwagandha (Withania somnifera).

Effect of different inoculum levels of P. arborescens in disease development and yield losses of opium poppy

Downy mildew (DM) caused by Peronospora arborescens is the most alarming disease of opium poppy which hampered the production of opium crop in major growing areas of India. The pooled data taken from Rabi 2016-17 and 2017-18 demonstrated that chemical protected un-inoculated plot had a minimum per cent disease severity (9.83) with maximum dry latex yield (31.25 kg ha-1), seed yield (801.31 kg ha-1) and husk yield (889.66 kg ha-1). However, plots inoculated with Peronospora arborescens at high inoculum density of 9×105 spores ml-1 had considerably higher per cent disease severity (67.00) and minimum dry latex yield (6.94 kg ha-1), seed yield (548.42 kg ha-1) and husk yield (590.86 kg ha-1) with maximum 77.79,31.56 and 33.58 per cent loss as compared to un-inoculated chemical protected plot, respectively. The severity of the downy mildew disease was found to rise in direct conflict with the level of inoculum concentration with significant reduction in dry latex yield, seed yield and husk yield.

Influence of weather parameters on alternaria leaf blight severity of makhana under the agro-climate of Koshi region of Bihar


 Weather parameters play a pivotal role in the infection process and spread of pathogen. It also influences the expression of susceptibility/resistance of the host plant during post-infection phases. Therefore, an experiment was conducted for two consecutive cropping seasons (2018 &2019) to study the influence of weather parameters such as temperature, humidity, rainfall and wind direction on the emergence of alternaria leaf blight of makhana in Koshi region of Bihar. Maximum per cent disease severity of alternarialeaf blightwas observed during the peak monsoon months (June to August). Highest disease severity of leaf blight (14.80% & 15.7%) was observed in the mid June during crop season, 2018 and 2019. High temperature (36.9oC & 38.1oC), and relative humidity (94% & 96.4%) of both the year 2018 and 2019 were found correlated with higher severity to alternaria leaf blight. Similarly average HTR values (3.1) were also found correlated with the average high temperature and relative humidity of both years (2018 and 2019) in terms of severity of leaf blight disease. Maximum temperatures, relative humidity and rainfall exhibited strong positive linear relationship and influenced the occurrence of alternaria leaf blight disease significantly. We also developed a geo-phytopathological model for the prediction of alternaria leaf blight disease of makhana on the basis of congenial mean temperature and relative humidity.

Effect of different inoculum levels of P. arborescens in disease development and yield losses of opium poppy

Downy mildew (DM) caused by Peronospora arborescens is the most alarming disease of opium poppy which hampered the production of opium crop in major growing areas of India. The pooled data taken from Rabi 2016-17 and 2017-18 demonstrated that chemical protected un-inoculated plot had a minimum per cent disease severity (9.83) with maximum dry latex yield (31.25 kg ha-1), seed yield (801.31 kg ha-1) and husk yield (889.66 kg ha-1). However, plots inoculated with Peronospora arborescens at high inoculum density of 9×105 spores ml-1 had considerably higher per cent disease severity (67.00) and minimum dry latex yield (6.94 kg ha-1), seed yield (548.42 kg ha-1) and husk yield (590.86 kg ha-1) with maximum 77.79,31.56 and 33.58 per cent loss as compared to un-inoculated chemical protected plot, respectively. The severity of the downy mildew disease was found to rise in direct conflict with the level of inoculum concentration with significant reduction in dry latex yield, seed yield and husk yield.

Application of bioagents/organic preparations for the management of Eumusae leaf spot disease of French plantain cultivar Nendran (Musa AAB) in Kerala

The efficacy of bioagents/organic preparations viz., cow dung extract + Pseudomonas fluorescens (1%), PGPR mix II (2%), P. fluorescens (2%), turmeric powder + baking soda mixture (5:1 per litre of water), salicylic acid (25ppm), KAU micronutrient multimix (Sampoorna) (1%), petroleum based mineral oil (0.1%) along with chemical check Bordeaux mixture (1%) and control were tested for the management of Eumusae leaf spot disease of French plantain cultivar Nendran ( Musa AAB). A field experiment was laid in the hotspot area of this disease at Banana Research Station, Kannara, Kerala during May 2016-2017 in Randomized Block Design (RBD) with nine treatments replicated thrice with nine plants per replication. The observations like Per cent Disease Severity (PDS), Youngest Leaf Spotted (YLS), Disease Development Time (DDT), vegetative and yield parameters were recorded. The results of the field experiments revealed that all the bioagents/organic preparations were equally effective in suppressing the disease when compared to the chemical check (Bordeaux mixture, 1%). Among the bioagents/organic preparations evaluated, the lowest per cent disease severity (PDS) of 20.93 per cent was recorded in plants sprayed with PGPR mix II (2%). While the maximum Disease Development Time (DDT) of 43 days and the highest (6.69) youngest leaf spotted were recorded in plants treated with turmeric powder + baking soda mixture (5:1) and Pseudomonas fluorescens (2%) respectively. The yield in terms of bunch weight was recorded highest (8.47 kg) in plants applied with P. fluorescens (2%) which was closely followed by PGPR mix II having a bunch weight of (7.93 kg). The study revealed that foliar spraying of PGPR mix II (20g/l) and P. fluorescens (20g/l) four times starting from the initial appearance of the disease on the lowest leaves of 75 per cent plants was safe and effective for the management of Eumusae leaf spot disease of banana

Field evaluation of fungicides against false smut disease of rice

False smut disease of rice caused by Ustilaginoidea virens is an emerging biotic stress of rice. A field experiment to evaluate bioefficacy of solo and combination fungicides against false smut disease of rice was conducted in two consecutive Kharif seasons (2017 and 2018). Experiment was laid out in a randomized block design with eleven fungicide treatments of three replications each. Disease was measured and expressed in percent disease severity following previously described method. The data obtained in 2017 and 2018 was analyzed after pooling. Among different fungicides tested, trifloxystrobin (25%) + tebuconozole (50%) 75 WG at 0.4 g/ litre was found highly effective in controlling the false smut disease with least per cent disease severity (35.87) followed by azoxystrobin (18.2%) + difenconozole (11.4%) SC at 1ml/litre (39.90). The fungicide identified can be used for effective management of false smut disease under field condition.

Bio-efficacy evaluation of Chlorothalonil 40% w/w + Difenoconfazole 4% w/w SC against apple diseases

Uttarakhand hills are best suited for production of a variety of fruit crops due to favorable agro-climatic conditions with apple being the most important temperate fruit grown in the region. Apple is the prime fruit of Uttarakhand and plays a major role in horticultural development and in improving economic status of the growers. The major diseases of apple crop in hill and mountain regions are scab [Venturia inaequalis (Cke.) Wint], premature leaf fall (Marssonina coronaria and Alternaria mali) and powdery mildew [Podosphaera leucotricha (Ellis and Everhart)] etc. These diseases have already plagued apple cultivation in Uttarakhand hills which happen to be the 3rd largest apple growing state of the country. Hence, to manage these diseases, Chlorothalonil 40% w/w + Difenoconazole 4% w/w SC at different dosages along with standard checks viz., Chlorothalonil 75% WP, Difenoconazole 25% EC, Propineb 70% WP, Sulphur 80 WG and Metiram 55% + Pyraclostrobin 5% WG at recommended doses were evaluated for bio-efficacy and phytotoxicity against apple scab, premature leaf fall and powdery mildew diseases at Harsil (District- Uttarkashi, Uttarakhand) during 2017 and 2018. The data analysis of two crop seasons (2017 & 2018) showed that all the treatments differed significantly with respect to per cent disease severity and per cent disease reduction over control for all the diseases studied. However, the treatment T4 (Chlorothalonil 40% + Difenoconazle 4% w/w SC @ 900 ml/ha) was found most effective followed by treatment T3 (Chlorothalonil 40% + Difenoconazole 4% w/w SC @ 800ml/ha) for all the diseases studied under present materials and conditions at Harshil location during 2017 and 2018. The data of two crop seasons indicated that maximum yield (98.83q/ha in 2017 and 95.20 q/ha in 2018) was recorded when the crop was sprayed with Chlorothalonil 40% + Difenoconazle 4% w/w SC @ 900 ml/ha followed by Chlorothalonil 40% + Difenoconazole 4% w/w SC @ 800ml/ha with 95.44 q/ha in 2017 and 94.55q/ha in 2018, respectively. For phytotoxicity studies, Chlorothalonil 40% + Difenoconazle 4% w/w SC @ 900 & 1800 ml/ha did not show any phytotoxic effects viz., yellowing, necrosis, chlorosis, epinasty, hyponasty and stunting on apple crop.

Effect of temperature and moisture levels on disease development of stem gall of coriander

Stem gall is one of the most important diseases of coriander. The effects of different temperature (15–35°C) and moisture levels (15-75 per cent) was studied on the development of stem gall of coriander caused by Protomyces macrosporus plants grown under controlled conditions. Results revealed that disease development was maximum (77.50%) at 25°C soil temperature followed by 30°C temperature giving 52.50 per cent disease incidence and 30.00 per cent disease severity, while very low and high temperature were not favourable for development of disease. In other experiment on different moisture regimes, 45 per cent of soil moisture level was favourable for disease development and resulted in 70.25 per cent disease incidence and 35.25 per cent disease severity. Very low and very high soil moisture levels were not favourable for disease development.

Influence of different SAR elicitors on induction and expression of PR-proteins in Potato and Muskmelon against Oomycete pathogens

Two cultivars each of potato namely; Kufri Badshah, Kufri Jyoti and muskmelon namely; Kajri and Punjab Hybrid were treated with varying concentrations of four different elicitors for induction of systemic acquired resistance (SAR) against Phytophthora infestans causing late blight in potato and Pseudoperonospora cubensis causing downy mildew in muskmelon. Attempts were made to induce SAR with application of various SAR elicitors as spray i.e. Jasmonic acid (JA), Salicylic acid (SA), Benzothiadiazole (BTH) and Beta Amino butyric acid (BABA). These elicitors were sprayed on 3-week-old sprouts and effect on defence related proteins along with late blight and downy mildew severity was studied. Leaf samples were collected up to 7 days post treatment and used for estimation of total proteins. Sporangial solution (4.0 × 104 sporangia per ml) was sprayed after 1 week of elicitors spray. Per cent disease severity was recorded at 14 days post inoculation. SA, JA, BTH and BABA caused statistically significant (at 5% level) increase in total soluble protein in leaf samples. The best treatments for maximum induction of proteins were 500 μM each of SA, JA, and BTH and 50 mM for BABA. SDS–PAGE electrophoresis confirmed that exogenous application of JA, SA, BABA and BTH resulted in the induction of PR proteins of low molecular size along with some other proteins in both potato and muskmelon, which helped in induction of SAR against oomycete pathogens.