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Open Access
Biocontrol of fusarial wilt of bottle gourd
(Punjab Agricultural University, Ludhiana, 2019) Ruchika, Ruchika; Narinder Singh
The wilt of bottle gourd caused by Fusarium oxysporum is a serious disease in bottle gourd growing areas of Punjab. Rhizosphere soil samples were collected from bottle gourd fields of Ludhiana, Kapurthala and Bathinda districts of Punjab in order to analyze the antagonistic microflora. Five isolates of Trichoderma and three isolates of Pseudomonas were isolated and screened in vitro for their antagonistic activity against Fusarium oxysporum. Among the various isolates, two isolates of Trichoderma (T1 and T2) and one isolate of Pseudomonas (P1) showed good inhibition against Fusarium oxysporum under lab conditions. Trichoderma isolate T2 showed maximum inhibition of Fusarium oxysporum (76.33 % and 65.83%) in dual culture and volatile assay, respectively. On Molecular characterization the selected isolates T1 and T2 were identified as Trichoderma asperellum and isolate P1 was identified as Pseudomonas aeruginosa. The selected isolates were then applied as seed, soil and seed + soil treatments using 10g and 15g formulation of each antagonist to check their efficacy against Fusarium oxysporum in two different seasons (March and June) under field conditions. Maximum germination (91.67% and 87.50%) and maximum disease inhibition (92.31% and 86.67%) was found in case of chemical treatment followed by Trichoderma asperellum isolate T2 with a germination of 87.50 per cent and a disease reduction of 84.62 and 80.00 per cent in March and June, respectively. Maximum yield (235.99q/acre and 229.00q/acre) along with maximum total length (5.43 m and 4.83 m) was obtained in case of Trichoderma asperellum isolate T2 in March and June, respectively due to disease control and the plant growth promoting behaviour of the antagonist. The results of rhizospheric competence showed that enough propagules of the antagonists were present throughout the growing season to effectively manage the wilt pathogen. Talc based bioformulation of the selected antagonists showed maximum shelf life on storing at 0°C and packing in polythene bags.
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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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BIOCHEMICAL AND HISTOPATHOLOGICAL STUDIES IN BARLEY FOR COVERED SMUT (Ustilago hordei) RESISTANCE
(Punjab Agricultural University, Ludhiana, 2019) Jashandeep Singh; Vineet Kumar
Covered smut caused by Ustilago hordei is an important disease of barley in India. In present study, biochemical basis of resistance, histopathological & ultrastructural changes and identification of sources of resistance to U. hordei were undertaken. The biochemical basis of resistance was studied on a set of three barley cultivars viz. PL 426 (resistant), PL 891 (moderately susceptible) and VJM 201 (susceptible). Maximum level of total phenols (0.64 units min-1 g-1 fresh weight) and activity of peroxidase (POD) (86.70 units min-1 g-1 fresh weight) was recorded in PL 426 whereas maximum activity of polyphenoloxidase (PPO) (89.30 units min-1 g-1 fresh weight) and phenylalanine ammonia lyase (PAL) (1.39 units min-1 g-1 fresh weight) was recorded in PL 426 and PL 891, respectively. The aqueous extract of seedlings of PL 426 (resistant variety) inhibited 98% of teliospores at 100% concentration. Ultrastructural comparison of compatible and incompatible Hordeum vulgare-Ustilago hordei, host-pathogen interaction done with scanning electron microscope showed germinated teliospores and trailing hyphae all over the host surface in the compatible interaction. Whereas, in incompatible interaction the teliospores were intact and extracellular polysaccharides were present completely adjacent to teliospores which might be involved in hindering the germination of teliospores. Eighty three germplasm accessions comprising of 74 germplasm lines and 9 varieties were evaluated against covered smut disease. Among the 9 varieties, 5 varieties namely HBL 113, HBL 391, HBL 316, DWRUB 92 and DWRUB 123 were found to be completely free from covered smut disease under field conditions at two locations viz. Ludhiana and Faridkot. PL 172 and PL 891 were categorized as moderately resistant and moderately susceptible, respectively. Among 74 germplasm lines tested at both locations, 41 showed high level of resistance and were found free from disease. BL 1562, BL 1656, BL 1627 and BL 1562, BL 1652 lines were found to be resistant at PAU, Ludhiana and RRS, Faridkot, respectively. 17 germplasm lines showed moderate resistance against covered smut.
Open Access
Etiology of charcoal rot of maize caused by Macrophomina phaseolina (Tassi.) Goid. in Punjab
(Punjab Agricultural University, Ludhiana, 2019) Ahmadi, Khalilullah; Harleen Kaur
Five different stages (55, 65, 75, 85 and 95 days old plants) of three maize hybrids viz. PMH 10, DKC 9108 and PMH 2 were evaluated for determination of most susceptible growth stage against charcoal rot during spring season. The data revealed that 75 days old plant was the most susceptible growth stage for charcoal rot. At this particular stage, mean disease severity (60.83 %) was maximum, resulting in minimum mean grain yield (55.27 q/ha).This stage also coincides with tasseling and silking stage of the plant. The effect of five different sowing dates on disease severity of charcoal rot of five maize hybrids during spring 2018 and 2019 revealed that crop sown on 20th January suffered minimum disease severity (40.91 and 36.3 %) resulting in maximum grain yield (74.27 and 77.89 q/ha) during spring 2018 and 2019 respectively. The plant height and cob height was found maximum on this date. As sowing date was delayed, severity of charcoal rot increased, thus decreasing grain yield, plant height and cob height. Among meteorological factors, disease severity was found positively correlated with mean temperature (+0.98) and negatively correlated with mean relative humidity (-0.92) and total rainfall (-0.90). The effect of three irrigation schedules (additional irrigation at tasseling and silking stage, local practice and stress at tasseling and silking stage) on the development of charcoal rot showed that application of an additional irrigation at tasseling and silking stage had least mean disease severity (36.28%) compared to other irrigation schedules and resulted in highest mean grain yield (72.61 q/ha). Water stress at tasseling and silking stage of the crop aggravated the disease development. Fifty four maize germplasm lines were evaluated artificially against charcoal rot, out of which five germplasm lines (PML-81, LTY 9808, JCY 13-1-1, SNL 172470 and SNL 172475) were found resistant, thirty moderately resistant, seventeen moderately susceptible and two of them were found highly susceptible. The maize hybrids sown in month of January and February coupled with additional irrigation at tasseling and silking stage resulted in low disease severity of charcoal rot, thus maximizing the grain yield. The germplasm lines found resistant after artificial screening of charcoal rot at the most susceptible growth stage (75 - 85 days old plants) during spring season could be successfully utilized in future breeding programme for maize improvement.
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Integrated management of Meloidogyne incognita and Rhizoctonia bataticola in root rot disease complex in mungbean
(Punjab Agricultural University, Ludhiana, 2019) Rohit Kumar; Dhillon, Narpinderjit Kaur
Mungbean crop is attacked by number of soil and air borne pathogens. Of the different soil borne pathogens; root-knot nematode (Meloidogyne spp.) is an important pathogen affecting growth and production of mungbean. Another soil and seed borne pathogen, Rhizoctonia bataticola causes root rot disease of mungbean. Meloidogyne incognita and R. batalicola being soil borne organisms may affect each other activity besides influencing the responses in their common host mungbean. Studies were conducted on the build-up of root knot nematode in nine different genotypes in summer and kharif season. The reaction of different genotypes was varied in two seasons. Eight of the nine genotypes were found to support multiplication of root knot nematode while decrease in nematode population was observed in only one genotype ML 2056. M. incognita populations in soil were observed to be significantly higher in kharif season in four genotypes viz., SML 1906, TMB 37, SML 1827, SML 1900 in comparison to summer season while in the other five genotypes there was no significant difference in the nematode population in two seasons. The interaction of M. incognita and R. bataticola revealed that higher incidence of root rot disease and maximum decrease in plant growth parameters was recorded in simultaneous inoculation of Meloidogyne incognita and R. bataticola. Of the one hundred two genotypes screened against M. incognita in summer and kharif mungbean; only ten genotypes were found to be moderately resistant. Of the eighty eight mungbean genotypes screened against Rhizoctonia bataticola only ten were moderately resistant. In multiple disease resistance studies, four genotypes which were moderately resistant against both pathogens were evaluated. Breakdown of resistance was observed in ML2581 and ML2560, while ML 2056 showed moderately susceptible reaction and ML2607 was observed to be moderately resistant against both pathogens. Integrated management of root knot nematode and R. bataticola in mungbean revealed that combined application of Bionematon@4l/ha + neem cake@1 t/ha + Captan (seed Treatment) was more effective than the individual application of chemical, bioformulation or cakes.
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Integrated management of Meloidogyne incognita and Rhizoctonia bataticola in root rot disease complex in mungbean
(Punjab Agricultural University, Ludhiana, 2019) Rohit Kumar; Dhillon, Narpinderjit Kaur
Mungbean crop is attacked by number of soil and air borne pathogens. Of the different soil borne pathogens; root-knot nematode (Meloidogyne spp.) is an important pathogen affecting growth and production of mungbean. Another soil and seed borne pathogen, Rhizoctonia bataticola causes root rot disease of mungbean. Meloidogyne incognita and R. batalicola being soil borne organisms may affect each other activity besides influencing the responses in their common host mungbean. Studies were conducted on the build-up of root knot nematode in nine different genotypes in summer and kharif season. The reaction of different genotypes was varied in two seasons. Eight of the nine genotypes were found to support multiplication of root knot nematode while decrease in nematode population was observed in only one genotype ML 2056. M. incognita populations in soil were observed to be significantly higher in kharif season in four genotypes viz., SML 1906, TMB 37, SML 1827, SML 1900 in comparison to summer season while in the other five genotypes there was no significant difference in the nematode population in two seasons. The interaction of M. incognita and R. bataticola revealed that higher incidence of root rot disease and maximum decrease in plant growth parameters was recorded in simultaneous inoculation of Meloidogyne incognita and R. bataticola. Of the one hundred two genotypes screened against M. incognita in summer and kharif mungbean; only ten genotypes were found to be moderately resistant. Of the eighty eight mungbean genotypes screened against Rhizoctonia bataticola only ten were moderately resistant. In multiple disease resistance studies, four genotypes which were moderately resistant against both pathogens were evaluated. Breakdown of resistance was observed in ML2581 and ML2560, while ML 2056 showed moderately susceptible reaction and ML2607 was observed to be moderately resistant against both pathogens. Integrated management of root knot nematode and R. bataticola in mungbean revealed that combined application of Bionematon@4l/ha + neem cake@1 t/ha + Captan (seed Treatment) was more effective than the individual application of chemical, bioformulation or cakes.
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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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Management of botrytis gray mold (Botrytis cinerea Pers. ex. Fr.) of chickpea through host resistance and fungitoxicants
(Punjab Agricultural University, Ludhiana, 2019) Jagmeet Singh; Upasana Rani
Botrytis gray mold caused by Botrytis cinerea is one of the most destructive diseases of chickpea. Maximum disease was observed in seedling inoculated from 5th to 25th February under 100 percent shade condition and disease development was more on PBG 5. Evaluation of chickpea inter-specific derivative lines (115) and germplasm (68) revealed that none of the line possessed high degree of resistance. Six inter-specific derivative lines (9054, 9056, 8007, 8018, 8022 and 8026) and two germplasm lines (GL-93011and GL-98010) showed moderately resistant reaction. Out of forty seven accessions of wild Cicer species, sixteen accessions (C. judaicum ILWC-95, C. judaicum ILWC-182, C. judaicum ILWC-185, C. judaicum ILWC-17148, C. reticulatum ILWC-237, C. reticulatum ILWC-141E, IC-525691, IC-525197, EC-366339, EC-366342, C. pinnatifidum ILWC-225, C. judaicum ILWC-223, C. pinnatifidum ILWC-261, C. pinnatifidum ILWC-0, C. pinnatifidum ILWC-263 and C. pinnatifidum ILWC-212) gave resistant reaction. Out of twenty seven lines derived from the cross of three parents (C. pinnatifidum 188, ICCV 96030 and PBG 1), only three lines (10008, 10009 and 10011) showed C. pinnatifidum 188 specific segment and moderately resistant reaction. These three lines were flanked by primers GA-22, GA-24, GA-105, NCPGR-127 and NCPGR-141. Testing of fungitoxicants by poison food technique (in vitro) showed that maximum per cent growth inhibition of 78.66 and 84.54 respectively was found in azoxystrobin + difenconazole 325 SC even at low concentration of 1 and 5 ppm respectively. Next best fungitoxicant propiconazole 25 EC gave more than 90 percent inhibition at 50 ppm. Similar results were achieved when these fungitoxicants were evaluated for sporulation at their respective concentrations. ED50 value of 1 μl ml-1 was achieved in azoxystrobin + difenoconazole, propiconazole and carbendazim. Non-systemic fungitoxicants were found to be non-effective against the pathogen. Azoxystrobin + difenoconazole 325 SC @0.1 percent with disease reduction of 88.68 per cent over control with per cent disease index of 7.72 as compared to check (68.24%) was followed by propiconazole 25 EC @ 0.1 percent disease reduction of 85.85 per cent over control with per cent disease index of 9.65 per cent.
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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.

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