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Open Access
POTENTIAL OF NATIVE STRAINS OF BIOAGENTS FOR THE MANAGEMENT OF DAMPING OFF IN ONION AND TOMATO
(Punjab Agricultural University, Ludhiana, 2020) Suma, Moka; Narinder Singh
Damping off is a destructive disease in onion and tomato caused by Fusarium oxysporum f.sp.cepae and Rhizoctonia solani in nursery growing areas of Punjab. Rhizospheric soil samples were collected from onion and tomato growing nurseries of Sangrur, Ludhiana and Amritsar districts of Punjab and analysed for antagonistic microflora. Seventeen isolates of Trichoderma and fifteen isolates of Pseudomonas were isolated and screened in vitro against the Fusarium oxysporum f.sp.cepae and Rhizoctonia solani causing damping off in onion and tomato respectively through dual culture technique, volatile and non-volatile compounds. Among all tested isolates Trichoderma isolate (T8) has shown maximum inhibition of Fusarium oxysporum f.sp.cepae (71.42%) and Rhizoctonia solani (84.22%) by dual culture. This isolate also showed maximum inhibition to Fusarium oxysporum f.sp. cepae and Rhizoctonia solani by volatile and non volatile metabolites of Trichoderma isolates. Pseudomonas isolate Pf10 has showed maximum mycelial inhibition of Fusarium oxysporum f.sp.cepae (64.37%) and Rhizoctonia solani (65.93%) by dual culture. It also showed mycelial inhibition of Fusarium oxysporum f.sp.cepae and Rhizoctonia solani by volatile and non volatile compounds released from Pseudomonas isolates. Biochemical tests for estimation of cell wall degrading enzymes has shown the ability of the Trichoderma isolate (T8) and Pseudomonas isolate (Pf10) to produce high level of chitinase (17.57 and 14.20 unit/ml respectively) and β-1,3-glucanase (1.42 and 1.52 unit/ml respectively). Pf10 also showed highest siderophore production of 33.67mm. The efficacy of talc based bioformulations of Trichoderma (T8) and Pseudomonas isolate (Pf10) when applied alone as well as in combination under pot and field conditions was checked against damping off of onion and tomato. In onion under field conditions, Pseudomonas (Pf10) and Trichoderma (T8) when applied as seed+soil treatment @15g/kg showed maximum inhibition of disease (89.99 and 88.75 percent respectively). They also acted as plant growth promoters with root length (14.64 and 14.17 cm), shoot length (25.33 and 25.00cm), fresh weight (4.51 and 4.45g), dry weight (1.82 and 1.80g) and finally yield (195.76 and 193.94 q/acre) of the crop. In tomato under field conditions Pf10 and T8 when applied as seed+soil treatment@15g showed maximum inhibition of damping off disease (88.89 and 85.71 per cent) with yield of 221.86 and 221.40 q/acre respectively. Pf10 and T8 (seed+soil treatments@15g) also acted as plant growth promoters with pooled root length (23.67 and 22.50 cm), shoot length (34.49 and 33.79cm), fresh weight (4.53 and 4.49g) and dry weight (2.22 and 2.19g) respectively during 2018 and 2019. Rhisosphere soil sampling from treated onion and tomato nursery up to 45 days showed decrease in antagonistic population up to 15 days and then it started increasing. The selected antagonists showed promising rhizospheric competency throughout the growing season that was enough to control damping off disease of onion and tomato in both pot and field conditions. Molecular identification of the Trichoderma T8 using endochitinase ech42 gene specific primers was done and found that it is closely related to Trichoderma asperellum and Pseudomonas isolate Pf10 using universal primer and sequence analysis showed similarity with Pseudomonas fluorescens. Study of shelf life of the talc based bioformulation revealed that antagonist Trichoderma asperellum (T8) and P. fluorescens (Pf10) can remain potent for 6 months when stored at room temperature while at low temperature storage (4° and 0°C) they can remain potent upto one year. For Mass multiplication sugarcane press mud, rice leaves and wheat bran supported rapid, maximum growth and sporulation of Trichoderma asperellum T8 at 25°C
Open Access
DIVERSITY AND ECO-FRIENDLY MANAGEMENT OF Helminthosporium spp. OCCURRING ON BARLEY AND OTHER GRAMINACEOUS HOSTS
(Punjab Agricultural University, Ludhiana, 2020) Amrinder Kaur; Vineet Kuma
Cereal crops all around the world are reported to be attacked by number of pathogenic microbes, among which the diseases incited by Helminthosporium species are economically very important. Among the 50 diseased samples collected during the survey from the various wheat, barley and oat growing areas of Punjab and adjoining states, Bipolaris sorokiniana was present in all the isolates from barley, wheat and Phalaris minor, while Drechslera avenae was found to be associated with the isolates from oats. All the cultures varied significantly with respect to their morphological traits. Total 12 isolates out of 50 were having greyish black growth of the mycelium on the PDA medium while, 34 and 4 isolates were whitish grey and greyish white, respectively. The pattern and margins of growth in most of the isolates were found to be raised and irregular, respectively. Three types of conidial shapes were recorded in all the isolates viz., oblong, elliptical and slightly curved with maximum conidial germination (95.70%) shown by isolate Bsb1 followed by Bsb42 (92.80%) and Bsw23 (91.28%) and it was minimum in isolate Bsb40 (51.20%) followed by Bsp33 (52.40%). All the 50 isolates were pathogenic towards their susceptible check PL426 (barley), HD-2329 (wheat), OL-9 (oats) and Phalaris minor. Minimum incubation period (2days), maximum no. of lesions per leaf (9.29), maximum size of lesions (9.30 mm2) and highest terminal disease severity score (89) were recorded with isolate Bsb1 from barley, followed by Bsw23 from wheat. The cross- infectivity of representative isolates of each host from each group viz., Bsb1 (barley), Bsw23 (wheat), Bsp34 (P.minor) and Da46 (oats) tested on different hosts revealed that all these isolates were found to be cross-infective on different graminaceous hosts except sorghum, rice and different weed hosts. Molecular variability studied among all the 50 isolates using ten different SSR markers revealed that primer BS 065 and BS 027 were found to be highly polymorphic as compared to other primers and thus can be used further for genetic diversity studies. Maximum melanin (µg/g of mycelium) production was recorded in the isolate Bsb1 (2.58 µg/g) followed by isolate Bsp34 (2.52 µg/g) and Bsw23 (2.49 µg/g) at 25°C, whereas, decrease in the trend of melanin production was observed at lower and higher temperature of 15°C and 35°C, respectively as compared to 25°C and 30°C. Among the different barley genotypes screened under field conditions, five genotypes (BL-1309, BL-1313, BL-1532, BL- 1562 and PL891) were found resistant and thirty three genotypes exhibited moderately resistant reaction to foliar blight pathogen. Considering the harmful effects of only use of fungicidal sprays, an eco-friendly approach was followed to manage foliar blight of barley. Maximum per cent growth inhibition (65.48%) under in vitro conditions was recorded with neem @15% followed by tulsi (45.37%) at the same concentration. Propiconazole 25EC @0.1% (standard chemical check) exhibited 100% mycelial growth inhibition as compared to the different botanicals tested and among bio-agents, T. harzianum exhibited 60.82% growth inhibition of the pathogen followed by T. viride as compared to the control. When these promising botanicals and bio-control agent were tested under field conditions for the management of foliar blight of barley, maximum per cent disease control (48.78%) was recorded with neem as compared to control. Among the different SAR chemicals tested under pot house conditions on two barley cultivars, PL 426 and PL807, maximum disease control (50.96%) was observed when the plants were sprayed with salicylic acid @ 0.03%, followed by 41.90% with BABA @ 0.3%. The promising doses of these SAR chemicals when tested under field conditions were found to be effective in controlling the disease upto 40 – 50% in susceptible cultivar PL 426 and upto 45 to 58% in the moderately resistant cultivar PL 807, as compared to the control and an increase was noticed in activity of defense enzyme (PAL) and phenol content of moderately resistant (PL807) and susceptible (PL 426) barley genotypes inoculated with the spore suspension of B. sorokiniana, however the increase was more pronounced in all the treatments in PL 807 as compared to the susceptible check PL 426. Thus, these disease management strategies could be further incorporated in IPM programmes for effective management of foliar blight disease of barley.
Open Access
Potential of native strains of Bacillus spp. against Fusarium wilt of watermelon
(Punjab Agricultural University, Ludhiana, 2020) Geetika; Buttar, Daljeet Singh
Fusarium wilt of watermelon caused by Fusarium oxysporum f.sp. niveum is a serious disease of watermelon growing areas of Punjab. Rhizosphere soil samples were collected from watermelon fields of Ludhiana, Jalandhar and Kapurthala districts and analysed for antagonistic microflora. Fifty isolates of Bacillus were isolated from the soil samples which were collected from rhizosphere soil of watermelon grown different districts of Punjab using serial dilution plating technique on the mannitol egg yolk polymixin medium. Out of 50 isolates, fifteen isolates of Bacillus were identified and purified based on morphological and biochemical character for further studies. The purified fifteen isolates of Bacillus were screened against the Fusarium oxysporum f.sp. niveum using dual-culture technique, volatile, non-volatiles and siderophore production under the laboratory conditions. B1 and B3 isolates of Bacillus spp. showed maximum (2.26 cm) zone of inhibition against Fusarium oxysporum f.sp. niveum under dual culture technique. These isolates showed 76.94 % and 79.20 % inhibition of pathogen in volatiles and non-volatiles production respectively. B1 isolate of Bacillus also showed highest chitinase and β-1,3 glucanase activity of 2.31 and 1.82 unit/ml, respectively. Similarly siderophore production in terms of halo zone (22.69 mm) was maximum in B1 isolate of Bacillus on Chrome-Azurol S media plate. The sequence of DNA showed on NCBI Blast that the nucleotide homology of the isolate B1 showed similarity with Bacillus subtilis strain 8102 (Accession number HQ123475.1). The isolate B3 based on nucleotide homology exhibited its similarity with Bacillus cereus strain LAR2-3 (Accession number KT151933.1). Efficacy of talc based bioformulations of Bacillus subtilis B1 and Bacillus cereus B3 were examined alone @ 5, 10 and 15g per kg of seed, in soil application ( 15 g per kg of soil) and seed + soil application included combination of both treatments (seed+soil). The chemical Bavistin @1.5 g per kg of seed was taken as standard chemical check. B 3 Bacillus cereus isolate applied as seed + soil @ 15g/kg of seed+soil treatment, showed maximum percentage of seed germination (93.33%), minimum percentage of disease incidence (6.67%) and maximum disease inhibition (87.51%) in watermelon plants in pots. Similar results were observed in B 1 Bacillus subtilis applied as seed + soil treatment @15g/kg of seed+soil showed maximum percentage of seed germination (90.00%), minimum percentage of disease incidence (10.00%) and maximum disease inhibition (81.24%) in watermelon plants in pots in kharif 2018 season. Similar trend was observed in kharif 2019 season. The talcum based bioformulations of these two isolates of Bacillus spp. were also further applied as seed treatment, soil treatment and seed + soil treatment and evaluated against wilt pathogen under field conditions. The maximum seed germination (95.83%) was recorded in both treatments of Bacillus subtilis B1 and Bacillus cereus B3 seed + soil @15 g per kg of seed/soil which was at par with the chemical treatment. The minimum wilt disease incidence (8.33%) was observed in the treatment of Bacillus cereus B 3 seed + soil @15 g/kg seed+soil followed by B1 seed + soil @15g/kg seed+soil treatment was 12.50 per cent. In addition to that these isolates of Bacillus spp. also promoted the plant growth parameter like root length, shoot length, their fresh and dry weight and ultimately increased the fruit yield of watermelon under both pots and field conditions. For the rhizosphere competence of the antagonist soil sampling at 15 days interval was done which showed that desirable colony forming unit count was present throughout the crop period in order to manage the pathogen effectively both under pots and field conditions. Maximum shelf life of talc based powder bioformulation of Bacillus subtilis B1 and Bacillus cereus B3 were recorded at low temperature storage (5°C) in polythene bags package. Therefore the finding concluded that Bacillus subtilis B1 and Bacillus cereus B3 significantly decreased the wilt incidence as compared to untreated control both under pot and field condition respectively. Both of these isolates significantly enhanced plant growth parameter and fruit yield. Hence enhanced the production and productivity of watermelon in Punjab condition.
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Characterization, population dynamics of Streptomyces spp. and management of potato scab
(Punjab Agricultural University, Ludhiana, 2019) Sabhikhi, Hardeep Singh; Hunjan, Mandeep
Scab of potato caused by various Streptomyces spp. has assumed serious proportions in certain potato growing regions of Punjab. A total of 2060 acres were surveyed during this study, out of which 490 acres were having scab infection. Maximum disease severity was observed in Kapurthala (7.9%), followed by Ludhiana (6.3%) and Jalandhar (6.2%) districts. During the surveys, it was observed that common scab type of symptoms were the most prevalent (89.7%), however disease induced by multiple type symptoms was viz., pitted or raised corky lesions was more severe. One hundred seven isolates of Streptomyces were collected, and characterized biochemically, pathotypically and genetically. All the Streptomyces spp. isolates could utilize hexose sugars, but not pentose sugars and most of the isolates produced melanoid pigment, an important virulence factor of this bacterium. Multiple antibiotic resistance was observed in 20 isolates. Pathotypic bioassay of Streptomyces spp. isolates revealed that Kufri Pukhraj had the highest virulence frequency (81.3%) while K. Himsona had the least (40.2%). Ninety six isolates were confirmed pathogenic. The 16srDNA amplification confirmed the identity of the genus, whereas sequence analysis of nine representative isolates revealed that Strep101 belonged to Streptomyces acidiscabies, Strep102 to reticuliscabiei, while Strep131, Strep137, Strep143, Strep145, Strep154, Strep170 and Strep173 to scabiei. All isolates were further characterized on the basis of pathogenicity genes, txtA and nec1.The txtA gene from Punjab isolates either matched with S. scabiei or S. turgidiscabies No txtA amplification was observed in S. acidiscabies, Strep101 and S. reticuliscabiei, Strep102. The nec1 gene was amplified in 84 out of 96 isolates and no nec1 was detected in S. reticuliscabiei, Strep102. Genetic fingerprinting carried out by using 17 RAPD primers clustered these into eight genetic groups. Many genetic groups had multiple virulence groups and vice-versa. To identify resistant donors, 41 potato germplasm lines were screened using representative isolates of different virulence groups. Most of the lines were susceptible to moderately susceptible. Three crop rotations viz., fallow-rice-potato, summer moong-rice-potato and sunhemp-rice-potato showed maximum per cent decrease in the population of Streptomyces spp. in soil and scab severity on potato tubers. Using disease free seed tuber or early harvesting of potato from scab sick field also observed that to reduce scab effectively. In vitro and in vivo evaluation of different chemicals against S. scabies showed that Streptocycline, streptomycin, boric acid and copper sulphate were effective. However, tuber seed treatment with chemicals viz., Kocide@0.2% and Streptocycline@100 ppm and antagonist Streptomyces spp. strain S25 and S27 had negative impact on the germination of potato seed tuber. For the management of scab, complete package involving use of tolerant cultivars, disease free seed or seed treatment, and cultural practices have to be followed.
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Over summering behaviour of Puccinia striiformis f. sp. tritici Erikss., the incitant of yellow rust of wheat and its management
(Punjab Agricultural University, Ludhiana, 2019) Tak, Parminder Singh; Pannu, P.P.S.
Yellow rust of wheat was found to survive in off season on main crop, self grown plants, ratooned plants and abandoned un-harvested plants/ fields in nine regions viz. Janjehli and Rohanda (Mandi), Bhalyani and Pulga (Kullu), Galu (Shimla), Haripurdhar (Sirmaur), Keylong in H.P. and Kargil and Leh in J&K from April to October. Aeciospores of rust from barberry caused chlorotic specks on susceptible wheat cultivar PBW 343, but no further sporulation was observed even after one month. Average minimum temperature influenced incubation period, latent period and disease severity. Incubation period increased to 19 days and 14 days with minimum average temperature above 12˚C and below 6˚C, respectively even when RH was around 90%. Minimum temperature in the range of 7-13˚C, relative humidity ≥ 90%, frequent rains during Feb-March along with winds are congenial for development and spread of yellow rust. No infection developed on barberry under in situ conditions when inoculated with teliospores from wheat. Twenty nine polymorphic SSR primers revealed polyphyletic origin of the races of Pst. Bhutti and Bhalyani (Kullu) isolates grouped together with Pst 46S119 isolate from Santokhgarh adjoining Punjab. Isolates from Sundarnagar (H.P.) grouped with Pst isolate from Fatehgarh Sahib (Punjab). Primer pair Scaffold233-153774 and Scaffold904-62635 were found to differentiate Pst 46S119 and 110S119, respectively. Barberry rust isolates were not amplified by any SSR primers specific to Pst, indicating them to be different from Pst. Early sowing (October) of wheat resulted in highest disease severity and highest area under disease progress curve as compared to November sowings. Out of four wheat varieties tested, PBW 343 was found to give highest AUDPC of upto 2041.7. Fungicides viz. Amistar top 325SC, Amistar xtra 280SC, Custodia 320SC, Opera 175SE and Tilt 25EC @ 0.1%, Nativo 75WG @ 0.6% and Taqat 75WP @ 0.3% were found to give almost complete control of yellow rust along with significant increase in thousand grain weight (26.0 to 30.3 %) and increase in yield varying from 33.3 to 40.2 per cent. Amistar top 325SC reduced the average plant height, but recorded maximum tillers in both the years without any adverse effect on yield. Maximum activity of PAL, PPO and POX was observed in resistant variety PBW 725 as compared to susceptible cultivar HD 2967. Enzyme expression under challenged conditions was more than un-challenged. Highest PAL activity was observed in Nativo, PPO in fermented butter milk and POX activity in Opera, where elevation of 10.8, 1.8 and 5.6 fold, respectively was observed as compared to unchallenged conditions. Timely sowing, varietal diversity, cultivation of resistant/ tolerant varieties, monitoring of crop during December – January, management of initial foci of infection in disease prone areas and timely advisories based on weather forecasting has been found the best strategy for management of yellow rust in Punjab.
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Characterization of Phytophthora species associated with citrus foot rot and its management in Punjab
(Punjab Agricultural University, Ludhiana, 2019) Yesmin Kaur; Thind, S.K.
Foot rot of citrus caused by Phytophthora spp. is major threat to flourishing citrus industry across the world. During surveillance, maximum disease incidence was recorded in Fazilka and minimum in Sangrur districts of Punjab. Among different agro-climatic zones of Punjab, maximum incidence was recorded in arid-irrigated zone and minimum in central zone. The disease incidence was more on Grapefruit and less on Kinnow cultivars of citrus. Oat meal agar medium was best for growth of Phytophthora. The causal agent of the disease was identified as Phytophthora nicotianae on the basis of morphological and molecular characters. Phytophthora survival was highest in irrigated and inoculated soil planted with Rough lemon seedlings and diminished in unirrigated bare soil after 15 months of inoculation. The population was maximum at 0-8 inches depth and was positively correlated with the plant root density. Maximum population was recorded in the months of July-September with temperature of 28.0-32.5 °C and relative humidity of 71.5 to 75.0 per cent. Leaf baiting was found best for detecting Phytophthora population after 24 hours with 1:1 soil and water ratio. A set of seventeen SSR primers generated 67 to 100 per cent polymorphism. Metalaxyl resistant isolate of Phytophthora showed reduced sensitivity to Ridomil Gold 68 WP at 1, 10 and 50 μg/ml with ED50 value of 30.0 μg/ml. Ridomil Gold 68 WP, Profiler 71.1 WG and Curzate M8 72 WP were found effective in vitro and in vivo against Phytophthora. Profiler 71.1 WG and Curzate M8 72 WP were also effective against metalaxyl resistant isolate.
Open Access
Dyanamics of inoculum affecting occurrence of karnal bunt epidemic in wheat
(Department of Plant Pathology College of Agriculture, 2001) Kaur, Sarbjeet; Chahal, S. S
Open Access
Studies on grey mould of gram caused by botrytis cinerea in the Punjab
(Department of Plant Pathology College of Agriculture, 1984) Meeta, Madhu; Bedi, P. S
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Detection of phytopathogenic bacteria from cowpea and mung seeds
(College of Agricultural Engineering PAU - Ludhiana, 1982) Soni, Parmjeet Singh; Thind, B. S

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