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ThesisItem Open Access Studies on maydis leaf blight of maize caused by Bipolaris maydis (Nisikado and Miyake) Shoemaker(CCSHAU, 2017) Manjeet Singh; Mehra, RakeshThe maydis leaf blight disease of maize (Zea mays L.) caused by Bipolaris maydis has emerged as a serious problem in most of the maize growing places of India, leading to considerable yield losses in maize. The present investigation on epidemiology, management and variability (cultural, morphological, pathogenic and genetic) were carried out with twenty six isolates of B. maydis collected from maize growing areas of the country. Out of four dates of sowing of maize, the highest disease intensity, AUDPC and AIR was observed in Ist date of sowing (15 June) followed by IInd date of sowing (27 June), IIIrd date of sowing (10 July) and least disease intensity in IVth date of sowing (25 July) on all the five hybrid and inbreds. Maximum temperature range of (32.2-34.20C), minimum (23.7-25.30C) with relative humidity morning (88-93%) and evening (59.5 -76.7 %), rainfall (0.0-7.4 mm), evaporation (2.6-3.9 mm), sun shine (4.8- 9.7 h/day) and wind speed (2-3.4 km/h) were most congenial for disease progression during Kharif 2015 and 2016. Temporal increase was maximum in 33th to 34th and 36th to 37th metrological weeks in all the five hybrid/inbreds during both the years. Disease progression, AUDPC and AIR value were more in Kharif 2016 as compare to Kharif 2015 however, among the five hybrid/inbreds highest in HKI-PC4B and minimum on HM-4 in all four date of sowing during Kharif 2015 and 2016. Relative humidity, rainfall and temperature showed important role in disease progression. Regression equations on relationship between disease development and weather parameter have been developed for five maize hybrid/ inbreds. Out of one hundred and two inbred lines and one hundred and four hybrids of maize screened against maydis leaf blight under artificial inoculated conditions, six inbreds and eighteen hybrids found resistant respectively. Out of eight fungicides evaluated against B. maydis, propiconazolee and tebuconazole provided maximum per cent growth inhibition, disease control and also increase yield. Among twelve plant extracts evaluated against B. maydis, garlic clove and neem leaves extracts at 20 per cent concentration were found most effective both under in vitro and in vivo conditions. Bio agents, Trichoderma harzianum and T. viride found most effective under in vitro, screen house and field conditions. For integrated disease management, combination of propiconazolee (0.1%) + garlic (20%) + T. harzianum and tebuconazole (0.1%) + neem (20%) + T. viride were most effective and also increase the yield. All the twenty six isolates identified, belonged to B. maydis based on their morpho-cultural characteristics. Among the isolates, BM-22 and BM-23 from Gogunda and Fateh Nagar recorded maximum colony diameter. The growth pattern varies among twenty six isolates of B. maydis showed rough or smooth texture, regular or irregular margin with or without zonation, mycelium of isolates was either appressed or raised type. The colors of the colony were highly variable and size of conidia ranged 28.38-77.40 × 10.32-23.22μm. The conidia size of isolate BM-20 was largest (63.98 × 15.74 μm) with highest average number of' septa (5.9). In pathogenic variations, the isolate BM-16 from Karnal was most virulent and aggressive in comparison to other twenty five isolates of B. maydis, as it showed shortest mean latent period (39.6 h) and maximum mean disease score (4.1) across ten maize genotypes. Molecular variability among the twenty-six isolates of B. maydis has been examined through RAPD and ITS analysis, isolate BM-3 isolate to remain alone in the dendrogram, whereas maximum closeness (97%) was observed between BM-24 and BM-25 isolates.ThesisItem Open Access Epidemiology, morpho-pathogenic variability and management of white rust of Indian mustard incited by Albugo candida (Pers. ex. Lev)(CCSHAU, 2017) K. Basavaraj; Rathi, A.S.White rust disease caused by Albugo candida is an important disease of Indian mustard (Brassica juncea.) in India particularly in northern and North eastern states. Keeping in view the enormous loss caused by the pathogen, the present study has been devised on epidemiology, variability and management studies under field and screen house conditions during rabi 2014-15 and 2015-16 at CCS HAU, Hisar. In epidemiological studies the two Indian mustard varieties namely RH 30 and RH 0749 were sown in different dates to observe the influence of weather factors on onset and progression of the disease. The white rust disease appeared early in the season i.e. last week of December in first three dates of sowings while a week delayed in late sown crops. Initially, after the onset of the disease, disease was slow and non-significant; however it gained momentum and showed significant difference among the observations in all dates of sowing from second week of January. The highest disease intensity was observed during the third week of January. The disease was rapid and more severe on variety RH 30 as compared to RH 0749. The severity was observed to be more with the delayed sowing. Investigation on selective criteria for Indian mustard genotypes for white rust intensity and yield revealed that, existence of great variability among the all the genotypes for white rust intensity and yield characters under all the three environments such as natural, artificially pathogen inoculated and pathogen controlled environment. The disease severity was more in environment where the zoosporangial suspension was artificially inoculated to create a disease pressure compared to naturally infected and controlled environments. In general the genotypes RH 9801, RH 9304 recorded the minimum disease severity while the genotypes RB 50, RH 0725, RH 0673 and RH 1134 were found to be highly susceptible. The genotypes RH 8812, RH 9304, RH 0749 performed better with uniform superiority under both no disease stress and disease stress conditions. So such genotypes can be encouraged to use in breeding programme. The variability among the Albugo candida isolates collected from the six different locations of Northern India and also from the different Brassica species from the Hisar showed considerable variation in morphology and pathological reactions on set of Brassica host species. The isolates showed greater variation in size and germination percentage of sporangia; however very less variability was observed for the shape of sporangia in which all the isolates exhibited spherical to globose. Based on the pathogenic reaction on set of Brassica species, Hisar, Bawal, Bharatpur and Ludhiana were seems to be similar. The Pantnagar and Delhi isolates seems to be entirely distinct isolates from Northern India. The results of cross inoculation studies indicated about existence of variability in the isolates and five groups were identified among the isolates. Among the different fungicides tested for their efficacy against white rust, spray of mancozeb 75 WP 45 DAS @0.2% followed by azoxystrobin 23% SC @ 0.05% at 60 DAS gave maximum control of the disease at both leaf and staghead phase with higher seed yield.ThesisItem Open Access Studies on blue mould rot of aonla (Emblica officinalis Goerth.) caused by Penicillium islandicum (Sopp.)(CCSHAU, 2017) Saini, Anil Kumar; Sharma, Sushil KumarAonla or Indian gooseberry (Emblica officinalis Goerth. Syn. Phyllanthus emblica L.) is one of the most important indigenous fruit of Indian sub continent. The blue mould rot caused by Penicillium islandicum adversly affects the fruit quality, quantity and ultimately reduces the marketable value. In India, nearly 20 – 35 per cent of perishables are lost due to post harvest diseases. Keeping the above facts in view, the present study was undertaken to survey orchards and terminal markets of Hisar and Rewari districts of Haryana, screen different varieties, study the various biochemical and epidemiological factors, and to develop suitable strategies through use of fungicides, chemicals, bioagents and botanicals for management of blue mould rot of aonla. Fortnightly survey carried out from November to January, 2015-16 revealed that blue mould rot incidence was higher in terminal markets of Hisar and Rewari Distt as compared to orchards in the respective locations. Varietal screening revealed that least blue mould rot intensity was found in Desi (2.67%) and Kanchan (3.33%) while maximum rot was observed in Chakaiya (50.00%) and Banarsi (49.33%) aonla varieties. In biochemical studies, it was observed that total soluble solids, total phenol, peroxidase and polyphenol oxidase activity increased in diseased fruits in comparison to healthy fruits, while ascorbic acid and acidity decreased over time in both healthy and diseased fruits. The epidemiological studies revealed that the injury of the aonla fruits was found to be a pre-requisite for infection. A minimum number of 50 spores/ml was necessary for disease initiation whereas maximum blue mould rot incidence was noted at 30ºC and 100 per cent relative humidity. Relative efficacy of five chemicals against blue mould rot tested in vitro and in vivo at 0.2, 0.5 and 1.0 M concentrations revealed that boric acid at 1.0 M concentration was the best to inhibit growth in pre- and post-inoculation after five and ten days of inoculation in both test conditions. In vitro and in vivo bio-efficacy studies involving ten plant extracts at 5, 10 and 20 per cent concentration for the management of blue mould rot indicated that treatment with neem leaf extract exhibited maximum mycelial growth inhibition (91.88%) at concentration of 20 per cent resulting in minimum pre- and post-treatment disease intensity of 7.31 and 8.13%, respectively, after five days of inoculation. Similar trend was also recorded in pre and post treatment after ten days of inoculation. Five bioagents were also studied for control of Penicillium islandicum by dual culture technique. Significantly highest per cent growth inhibition of P. islandicum was noted in Trichoderma harzianum (83.06%). T. harzianum with disease intensity 6.0 and 6.31 per cent was found most efficient antagonist in reducing the blue mould rot with disease intensity of 34.48 and 39.75% in pre- and post- inoculation, respectively, after five days of inoculation. Similar results were also obtained in pre- and post-treatment after ten days of inoculation.ThesisItem Open Access Studies on variability and anastomosis among the potato and rice isolates of Rhizoctonia solani Kuhn(CCSHAU, 2017) Pandit, Gurav Narayan; Surjeet SinghSheath blight of Rice and black scurf of Potato caused by Rhizoctonia solani has emerged as a serious problem in majority of rice-potato growing states of India, leading to considerable yield loss in both rice and potato crops. The present investigation on variability, anastomosis and cross infectivity was carried out with eighteen rice and eleven potato isolates of R. solani collected from different locations. Based on the radial colony growth rate, all the isolates from both the crops were categorised in to three groups as slow, medium and fast growing. Majority of rice isolates showed medium colony growth rate, while, most of the potato isolates showed slower growth rate. Potato isolates had colony texture either appressed or raised, whereas rice isolates had either raised or fluffy growth. Colony colour in all isolates was varied from pale yellow to very pale brown, while whitish color was appeared in rice isolate R16. Sclerotia were found aggregated at the centre of the colony in potato isolates, whereas it was scattered on colony surface in rice isolates. Colour of sclerotia in all rice isolates was dark brown while it was brown in Kurukshetra (R4) and black in Dapoli isolate (R18), however, it was varied from light brown to dark brown in potato isolates. Moderate to profuse sclerotial intensity was observed in rice isolates whereas it was scanty to moderate in potato isolates. Among the rice isolates, mean maximum lesion length was recorded in isolate R14 (Ludhiana isolate) which indicated strong pathogenic nature towards all four cultivars while lowest mean lesion length was observed in isolate R12 (Gurdaspur isolate) which indicated the least virulent nature.. Among the potato isolates, isolate P5 was found highly pathogenic to all the four varieties while the isolate P10 was found least pathogenic. On the basis of mean lesion length in rice and per cent disease severity in potato, all isolates from both hosts were categorized into three virulent groups viz., VG-I (less virulent), VG-II (moderately virulent) and VG-III (more virulent). Majority of rice isolates were moderately virulent while most of the potato isolates were less virulent. The diversity analyses using ISSR primers, exhibited genetic relatedness among the eighteen rice isolates ranged from 61 to 82 per cent with an average similarity of 70 per cent. The ISSR analyses differentiated R. solani isolates into two major clusters at similarity coefficient of 0.61. The maximum genetic similarity (82%) among all rice isolates was observed between isolate R4 and R5 while minimum genetic similarity (66& 66.5%) with all other isolates was observed by isolates R11 and R2, respectively. Similarly, the genetic relatedness among eleven potato isolate ranged from 63 to 86 per cent with average similarity of 70 per cent. On the dendrogram, two main clusters viz., group A and group B, were produced at 0.63 similarity coefficient. The highest genetic similarity (86%) was observed between isolate P1 and P2, whereas minimum (69.5 %) with all other isolates was shown by isolate P9. The present investigation on cross-infectivity of rice and potato isolates indicated that none of the potato isolates were able to infect all four rice cultivars. On the other hand, rice isolates showed varied degree of virulence on three potato cultivar. In anastomosis interaction studies, majority of isolates showed compatibility with isolates with those belonged to same host with few exceptions. There was no compatible reaction occurred between rice and potato isolates indicated that both the isolates belong to different and distinct groups within same species.