Cotton leaf curl disease (CLCuD), caused by the whitefly transmitted geminivirus complex (cotton leaf curl virus [CLCuV] and their satellite molecules), is a serious threat to successful upland cotton production in northwest India and Pakistan. The disease causes significant losses in fiber yield and the quality of cotton. Owing to the regular emergence of resistance-breaking strains of CLCuV, all the previously available CLCuD-resistant germplasms of upland cotton have become compromised, and none of the extant upland cotton cultivars is resistant to this disease. Therefore, alternate sources of CLCuD resistance need to be explored, as genetic resistance is the only pragmatic and tenable management strategy to combat this malady. Here, we report for the first time the introgression and mapping of CLCuD resistance from a related nonprogenitor wild diploid D-genome cotton species, Gossypium armourianum, into upland cotton. A backcross population (G. hirsutum/G. armourianum/G. hirsutum) was developed for this purpose. A single major QTL was found to be associated with resistance to CLCuD and was located on chromosome D01 through the genotyping-by-sequencing technique.

Cotton leaf curl disease (CLCuD), caused by a geminivirus complex, is the most serious disease of upland cotton in northwest India and Pakistan. It results in substantial losses in cotton yield and fibre quality. Due to continuous appearance of new viral strains, all the established CLCuD resistant stocks, extant and obsolete cultivars of upland cotton have become susceptible. Therefore, it became crucial to explore the novel sources of CLCuD resistance, as development of CLCuD resistant varieties is the most practical approach to manage this menace. Here, for the first time, we report introgression and mapping of CLCuD resistance from a 'synthetic cotton polyploid' to upland cotton. A backcross population (synthetic polyploid / Gossypium hirsutum Acc. PIL 43/G. hirsutum Acc. PIL 43) was developed for studying inheritance and mapping of CLCuD resistance. Dominance of CLCuD resistance was observed over its susceptibility. Two dominant genes were found to confer resistance to CLCuD. Molecular analysis through genotyping-by-sequencing revealed that chromosomes A01 and D07 harboured one CLCuD resistance gene each.

Rhizoctonia spp. which was earlier considered a minor disease causing pathogen under Punjab conditions now is a major threat to crops grown in Punjab. The present study investigated the morphological and cultural variations in Rhizoctonia population, pathogenic behaviour and extent of genetic differentiation between infecting populations of R. solani from different hosts. By species specific primers, Rhizoctonia species in Punjab were identified as R. solani (87.8 %), R. oryzae (11.1%) and R. oryzae-sativae (1.1 %). Morphological characterization of Rhizoctonia spp. based on the growth rate, colour of mycelium and sclerotial characters. A high degree of variation among these R. solani isolates was established. Potato isolates belonging to the different geographic areas of the state were clustered together and cotton isolates also related. R. solani isolates from maize, rice, wheat and chilli formed two major cluster groups. The molecular data on AG specific primers revealed that 46.8% of the isolates belonged to AG1-1A, while AG1-1B (10.1%), AG2-1 (13.9%), AG3 (12.7%). Using interspecific sequence repeat primers, isolates were clustered into three major groups (I, II, III). Group III consisted of isolates, mostly from Ludhiana irrespective of the hosts, indicating existence of genetic similarity among these isolates. Isolates were also found to partially group according to place of origin and the host. Further a partial relationship between the level of severity on rice was observed. The diversity and relatedness in hosts of R. solani isolates from Punjab indicates the need to consider the cropping pattern to reduce the inocula in the soil.

In India, Brassica is attacked by many bacterial, fungal and viral pathogens causing various diseases among which, downy mildew caused by Hyaloperonospora brassicae, an oomycete is the most severe one. The present investigation was conducted to reduce fungicide load on Brassica by testing an alternate method of disease control. Different Systemic Acquired Resistance (SAR) compounds were tested as foliar sprays like Salicylic acid, Jasmonic acid and Bion (Benzothiadiazole-BTH) for inducing resistance in different genotypes of Raya (Brassica juncea) against downy mildew pathogen. Protein content in plants ranged between 43.5 to 57.7 mg/g fresh weight compared to 37.2 mg/g fresh weight in control. Induction of proteins and defense related enzymes was systemic in nature. The SAR compounds also surged the levels of defense related proteins, i.e. Polyphenol oxidase (PPO), Phenylalanine ammonia lyase (PAL) and pathogenesis related Pr- proteins i.e. ?-1,3 glucanase, Peroxidase (POD), from 21 to 130 per cent indicating induction of resistance. Protein profiling of treated Brassica plants was also done electrophoreticaly, which further confirmed the induction of pathogenesis-related proteins ranging from 15- 75 kDa along with some other proteins. Salicylic acid @ 500µM showed best results with 71.27 per cent disease control followed by Jasmonic acid with 69.6 per cent; whereas both, Bion and ?eta amino butyric acid gave almost 63 per cent disease control as compared to control plants. Integration of disease tolerance in Brassica varieties/genotypes combined with prophylactic spray of salicylic acid proved to be very economical for managing downy mildew disease.

In India, vegetable crops are known to be attacked by many bacterial, fungal and viral pathogens causing various diseases. Out of the various diseases, downy mildew of cucurbits caused by Pseudoperonospora cubensis belonging to oomycete has become quite severe in the past recent years. The present study was conducted to reduce fungicide load and work out alternate method for control of this disease. Different SAR compounds were tested and exogenous foliar sprays of different conc. of Salicylic acid, Jasmonic acid and Bion (Benzothiadiazole-BTH) @ 50µM, 250µM, 500µM, 1000µM and β- amino butyric acid of 20 mM, 30mM, 50 mM, 100mM were given for inducing resistance in mushmelon against downy mildew pathogen. Concentration of Salicylic acid, Jasmonic acid and Bion @ 500 µM, and β- amino butyric acid @ 50 mM gave best control of disease among all tested concentrations. Protein content of treated muskmelon plants varied from 10.5 to 12.7 mg/g fresh weight compared to 5.2 mg/g fresh weight in control. Induction of proteins and defense enzymes was systemic in nature in response to all the four elicitors. The inducers also stimulated the activities of pathogenesis related proteins (Pr- proteins) i.e. β-1,3 glucanase, Peroxidase (POD), and defense related proteins i.e. Polyphenol oxidase (PPO), Phenylalanine ammonia lyase (PAL) from 18 to 180 % indicating induced resistance in treated muskmelon plants as compared to control. Electrophoretic protein profiling of treated muskmelon plants also confirmed the induction of pathogenesis-related proteins ranging from 15- 75 kDa along with some other proteins. Total chlorophyll and carotenoids also showed spike of 3% to 55 % in response to elicitors. Salicylic acid gave best results with 77.27 % disease control followed by Jasmonic acid with 76.6%; whereas Bion and Βeta amino butyric acid were almost at par with each other and gave 66 % disease control as compared to control plants. Thus integration of disease tolerance and salicylic acid spray resulted in effective and eco-friendly and very economical control of downy mildew of muskmelon.

In a study conducted at Punjab Agricultural University, Ludhiana during 2015-16 and aimed at exploring the variation in quality of seed-lots having different storage conditions, 50 seed potato lots of variety Kufri Pukhraj were collected at random from seed growers of Punjab. There was a large significant (P

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.

In a study conducted at Punjab Agricultural University, Ludhiana in collaboration with WUR, The Netherlands during 2013–14 and aimed at exploring the variation in quality of seed-lots having different storage conditions, 50 seed potato lots of variety Kufri Pukhraj were collected at random from seed growers of Punjab. Another objective of the study was to find relationships between storage conditions and performance of seed-lots after planting in the field. The seed-lots varied in respect of date of sowing, haulm killing and harvesting, seed size and storage conditions. There were large differences among seed-lots in terms of quality (Rhizoctonia, Fusarium dry rot and wet rot). The variation in seed-lots varied from 0–23, 0–90 and 0–30% in respect of Rhizoctonia, Fusarium dry rot and wet rot, respectively. The field experiment was conducted by taking all the 50 seed-lots as treatments and replicated thrice in randomized block design layout. The tuber yield among the seed-lots varied from 35.3 to 58.2 t/ha. The highest tuber yielder lot (number 32) was significantly better than the eight seed-lots (13, 24, 34, 37, 39, 44 and 47) and statistically at par with rest of the seed-lots. Though, we could not establish clear relationship between storage conditions and performance of seed-lots in the field due to large variation among seed-lots in respect of dates of sowing, haulm killing and harvesting and seed sizes yet the results indicated that for the state to establish itself as a quality seed potato hub for national and international market, there is need to bring uniformity in seed tubers being produced in the state.

Snapmelon downy mildew, an important foliar disease caused by Pseudoperonospora cubensis is an obligate parasite, which can survive and reproduce on living host tissue, causing significant yield losses. Forty six accessions of snapmelon were screened against P. cubensis in the cropping season 2015 and 2016. Plants were inoculated at optimum level of sporangial suspension (4.0 ´ 104 sporangia per ml) to create downy mildew. Out of forty six accessions, three were resistant having incidence in the range of 20-30 per cent and rest were moderately resistant, moderately susceptible, susceptible and highly susceptible. Significant mean maximum disease severity was observed in snapmelon accession SM 2013-7 and minimum in accession MC 2013-4. For further confirmation, biochemical studies of various defense enzymes were carried out in resistant accessions and compared with susceptible. The data pertaining to the activity of peroxidase, catalase, phenylalanine ammonia lyase and total phenols revealed significant differences (p=0.05) among the different accessions of snapmelon showing different reactions against P. cubensis. Higher activity of all those antioxidant enzymes were observed in resistant, followed by moderately resistant whereas activity gradually declined among susceptible and highly susceptible accessions. Negative values of Pearson’s correlation coefficient were obtained between antioxidant enzyme activity and disease development suggesting possible involvement of these enzymes in imparting disease resistance against downy mildew in snapmelon. The narrow genetic base of modern snapmelon accessions and a few sources of resistance make downy mildew resistance an important objective in snapmelon breeding programs. Thus, improving the genetic resistance of snapmelon to downy mildew through introgressive breeding could be an effective way to control this disease.

Exogenous foliar SAR elicitors like Jasmonic acid (JA), Salicylic acid (SA) and Benzothiadiazole (BTH) @ 500μM and Beta Amino butyric acid (BABA) @ 50 mM were tested to induce systemic acquired resistance (SAR) in muskmelon against downy mildew caused by Pseudoperonospora cubensis. Thirty-three germplasm lines/varieties of muskmelon were evaluated for three years and the results revealed that: eleven muskmelon varieties were moderately resistant and showed better response to SAR elicitors against P. cubensis. These elicitors were sprayed on three-week-old plants and effect on induction of defence related proteins and downy mildew severity was studied. Leaf samples were collected upto 7 days post treatment for estimation of total proteins. Sporangial solution (4.0 x 104 sporangia per ml) was sprayed after one week of elicitors spray and per cent disease severity was recorded at 14 days interval. SA, JA, BTH and BABA caused statistically significant increase in total soluble protein in sprayed as well new unsprayed leaves indicating systemic induction of defense related proteins. Mean maximum protein i.e. 11.4 mg/g FW was highest in SA treated, three muskmelon varieties i.e. Punjab Sunehri, MC 2012-9 and MM105-Kajri followed by 11.2 mg/g FW in Hemed and 11.1 mg/g FW in MM4305, respectively. Maximum per cent disease control of 93.48 was observed in SA treated Rough skin variety followed by MM3843 and MM4305 with disease control of 92.07 and 91.27%, respectively. Minimum disease control was observed in BTH treated Kajri plants. Foliar application of SA was most effective followed by JA, BABA and BTH. The response was higher in moderately resistant variety but susceptible variety also showed better response as evident by decreased disease severity. Therefore application of elicitors followed by inoculation with P. cubensis help in eliciting the levels of defense related proteins which play an important role in protecting muskmelon against downy mildew disease.

Dry rot caused by Fusarium spp. is one of the major diseases causes significant loss in cold storage. For its management fungicides namely Ridomil Gold 68 WP, Mancozeb 75 WP, Bavistin 50 WP and Amistar screened in vitro through poisoned food technique. Bavistin 50 WP and Ridomil Gold 68 WP were found significantly effective in inhibiting the mycelial growth of pathogen. Bavistin and Ridomil Gold were tried as tuber spray and tuber dip treatments at different concentrations under in vivo conditions. Bavistin was found effective as tuber dip treatment. All the tested fungicides were also evaluated under cold storage. Bavistin was also found to be most effective in which maximum disease control was observed as 77.6 per cent and 87.1 in 5 per cent and 15 per cent infected grade tubers, respectively. The maximum effect of dry rot was observed in highly infected grade tubers (>50%). Positive correlation was found between injury and dry rot incidence under cold storage.

To find out development of resistance against commonly used fungicides namely propiconazole and pencycuron, Rhizoctonia solani isolates were tested in vitro at different concentrations ie. 0, 1, 10, 25, 50, 100 and 250 ppm. Eighty five out of total 99 isolates showed sensitive reaction to propiconazole below 50ppm concentration in food poisoning technique, which indicated development of resistance in R. solani rice isolates. Ten R. solani isolates showed growth inhibition at 100 ppm and four isolates were least responsive and showed growth inhibition only at 250 ppm concentration. All isolates collected from different hosts like maize, potato, cotton and chilli were found to be sensitive in their reaction to pencycuron but only a few isolates of R. solani from rice showed inhibition at higher concentration of pencycuron. Pencycuron was found to inhibit large number of R. solani isolates at low doses when compared with propiconazole. The ED90 values for most of the insensitive R. solani isolates were found to be in the range of 14 to 26 ppm for pencycuron and it was in the range of 27 to 78 for propiconazole. These preliminary studies indicated that there was development of fungicide tolerance in R. solani rice sheath blight isolates. Those isolates which were found sensitive to higher concentration of propiconazole (Tilt 25 EC) and pencycuron (Monceren 250SC) were evaluated under artificial inoculated conditions in the field on rice variety PR 114. At 0.1% spray concentration of Tilt 25EC, disease control was recorded in the range of 54.3 to 99.4% in different isolates, but when a double dose ie. 0.2% was applied under field conditions; very effective disease control was achieved in all these R. solani isolates as percentage decrease in sheath blight was above 93 per cent.

Relative performance with respect to bio-efficacy, phytotoxicity and impact on vigour of four seed treatment fungicides belonging to different groups was assessed against Pythium aphanidermatum, Rhizoctonia solani and Fusarium oxysporum f.sp. lycopersici, responsible for damping-off disease in tomato nurseries. The combination of carboxin+thiram and carbendazim were found effective in inhibiting R. solani (IC50=47.01 and 57.47 μg/ml, respectively) and F. oxysporum f.sp. lycopersici (IC50=48.14 and 24.63 μg/ml, respectively), but provided comparatively lesser inhibition of P. aphanidermatum (IC50 > 500 μg/ml) under in-vitro conditions. Captaf was adjudged inferior to carboxin+thiram and carbendazim in inhibiting R. solani (IC50=167.8μg/ml), F. oxysporum f.sp. lycopersici (IC50=129.08μg/ml) but comparatively better against P. aphanidermatum (IC50 > 500 μg/ml). Tebuconazole provided excellent broad-spectrum efficacy against all the three fungi in vitro but showed phytotoxicity to seedlings. Seed dressing with carboxin+thiram was adjudged superior in controlling pre-emergence seed rot followed by carbendazim and captaf but at post-emergence stage, all the four treatments were found at par but significantly better than the untreated seeds. Seedling vigour studies revealed that seedling length was significantly affected with seed treatments. Carboxin+thiram increased the shoot length significantly and germination of seeds compared to untreated control. Though tebuconazole exhibited promising activity against all three test fungi and also reduced the disease significantly, but severely reduced shoot length of seedlings. Seed treatment with all the test fungicides increased germination but best being carboxin+thiram as it caused 8.40 per cent increase over the untreated seed.