Percent Disease Index Research Articles

Screening of fungicides and plant extracts for controlling blight disease of Tagetes spp.

A field experiment was conducted in the Botanical research garden, Department of Botany, University of Dhaka during 2015, 2016 and 2017 to evaluate the efficacy of two fungicides and two plant extracts against blight disease of Tagetes erecta L. and T. patula L. Both the fungicides Bavistin 50 WP and Tilt 250 EC and leaf extracts of Azadirachta indica A. Juss. and Citrus medica L. showed effective management of the disease over the untreated check. However, among the treatments, Bavistin 50 WP and Tilt 250 EC at 100 ppm concentration and A. indica and C. medica L. at 10% concentration were found significantly superior in controlling percent disease index and increasing number of healthy flowers. The number of healthy flowers was highest per plant, 17.13 in T. erecta in 2017 and 25.00 in T. patula in the year 2016.
 J. Asiat. Soc. Bangladesh, Sci. 47(1): 79-89, June 2021

Correlation Analysis for Leaf Pubescence, Leaf Micro-macro Nutrient Content and MYMV Disease Index in Blackgramgenotypes (Vigna mungo (L.) Hepper)

The present field study was conducted to characterize the blackgram genotypes based on morpho and nutrient content under yellow mosaic virus disease infection. The present investigation was carried out with ten blackgram genotypes (5 known tolerant + 5 known susceptible) in Randomized Block Design (RBD) during summer 2018. Experimental crop was affected by yellow mosaic virus (YMV) naturally at 30 DAS. No management practices were taken for controlling of whitefly population during crop season. Correlation studies were done at 50 DAS which helps to find out the most resistant and most susceptible genotypes among ten backgram genotypes based on leaf pubescence and nutrient content in leaf. Leaf pubescence is one of the most important resistant factors in a number of crops and Minerals, apart from being a vital part of the plant nutrition, may manifest certain maladies in the plants either through disturbing normal metabolism and physiology of the plants or by favouring or by discouraging the plant pathogens, if in excess or otherwise deficient.
 Correlation analysis of present field investigation revealed that blackgram genotypes showed strong negative correlation for leaf pubescence, leaf Phosphorous (P) and leaf potassium (K) content with percentage disease index (PDI%) as well as strong positive correlation for leaf Nitrogen (N), leaf Iron (Fe) and leaf Zinc (Zn) content under YMV.

Identification of Source of Resistance to Horse Gram Yellow Mosaic Disease (HgYMD) in French Bean (Phaseolus vulgaris L.)

Background: Horse gram yellow mosaic disease (HgYMD) is one of the major limiting factor for legumes production in India as it can cause economic loss up to 100%. Till date, horse gram yellow mosaic virus was rare to infect french bean, but now-a-days, it has become the major causal agent for yellow mosaic epidemics in the southern part of India. Few bush type varieties, resistant to yellow mosaic disease are released but not specifically resistant to HgYMD. So, systemic breeding work has been initiated to identify the resistant source for HgYMD in french bean. Methods: Seventyone genotypes of french bean were screened in a randomized complete block design (RCBD) with three replications under natural epiphytotic as well as artificial condition during Summer, 2018 at ICAR-IIHR, Bengaluru, India. Result: The genotypes varied for percent disease index (PDI), area under disease progress curve (AUDPC) and the apparent rate of infection per unit time period (r). Two varieties i.e., Jade-5058 and Arka Arjun were showing less PDI of 13.33 and 14.44, least average rate of infection of 0.64 and 0.65 and lowest AUDPC value of 350.54 and 359.16 respectively, compared to other genotypes. Average PDI of Arka Arjun and Jade-5058 were 13.33 and 12.22 under artificial screening, which were much lesser than susceptible check Arka Komal (PDI 92.22) and Arka Anoop (PDI 90.00). Resistant genotypes identified from this experiment can be used for breeding HgYMD resistant french bean lines.

Pattern of genetic variation in rice (Oryza sativa L.) population for sheath blight resistance over the seasons

A set of 192 indica rice accessions were evaluated in two seasons to generate information on the extent of genetic variability, broad-sense heritability and genetic advance for yield and sheath blight related traits. The estimated genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) varied over the season. Largely, PCV values were relatively higher than GCV with reference to the studied parameters. However, GCV was found to be medium for per cent disease index (PDI) of 14th day, 28th day, area under the disease progress curve (AUDPC), and tiller number over the seasons. Interestingly, grain yield was found to be high. The trait plant height and panicle length had moderate heritability coupled with moderate genetic advance, whereas AUDPC was moderately heritable coupled with high genetic advance. The findings may be useful in breeding improved rice genotypes.

Role of biochar, compost and plant growth promoting rhizobacteria in the management of tomato early blight disease

The individual role of biochar, compost and PGPR has been widely studied in increasing the productivity of plants by inducing resistance against phyto-pathogens. However, the knowledge on combined effect of biochar and PGPR on plant health and management of foliar pathogens is still at juvenile stage. The effect of green waste biochar (GWB) and wood biochar (WB), together with compost (Comp) and plant growth promoting rhizobacteria (PGPR; Bacillus subtilis) was examined on tomato (Solanum lycopersicum L.) physiology and Alternaria solani development both in vivo and in vitro. Tomato plants were raised in potting mixture modified with only compost (Comp) at application rate of 20% (v/v), and along with WB and GWB at application rate of 3 and 6% (v/v), each separately, in combination with or without B. subtilis. In comparison with WB amended soil substrate, percentage disease index was significantly reduced in GWB amended treatments (Comp + 6%GWB and Comp + 3%GWB; 48.21 and 35.6%, respectively). Whereas, in the presence of B. subtilis disease suppression was also maximum (up to 80%) in the substrate containing GWB. Tomato plant growth and physiological parameters were significantly higher in treatment containing GWB (6%) alone as well as in combination with PGPR. Alternaria solani mycelial growth inhibition was less than 50% in comp, WB and GWB amended growth media, whereas B. subtilis induced maximum inhibition (55.75%). Conclusively, the variable impact of WB, GWB and subsequently their concentrations in the soil substrate was evident on early blight development and plant physiology. To our knowledge, this is the first report implying biochar in synergism with PGPR to hinder the early blight development in tomatoes.

The potential impact of Octopus cyanea extracts to improve eggplant resistance against Fusarium-wilt disease: in vivo and in vitro studies.

The novelty of the present research is conducting a new method in the systemic resistance of plant diseases by using distinct marine extracts. The ability of two octopus extracts to reduce the wilt disease caused by Fusarium oxysporum was observed. The applied methods are soaked roots (SR) and foliar shoots (FS). The antioxidant enzyme activities, percent disease index (PDI), and growth parameters were measured. In vitro antifungal potential of the octopus extracts against F. oxysporum was examined. The obtained result shows that SR extracts reduced PDI. Additionally, all the tested treatments promoted the growth and photosynthetic pigments of the infected plants. SR (in ethanolic extracts) was the most prominent inducer which offered a high advancement in the total soluble protein contents. Also, SR (in methanolic extracts) was the most suitable inducer which provided a very necessary development not only in the total phenol but also in the peroxidase (POD) and polyphenol oxidase (PPO) activities. GC-MS investigation of the octopus extracts exhibited that the compounds which possess antifungal activity were furoscrobiculin B and/or eugenol. They demonstrated a notable antifungal potential against F. oxysporum with a maximum activity of 38.5 and 12.7 mm ZOI after the treatment with the ethanolic and methanolic extract, respectively. FTIR results illustrated the functional group of the compound responsible for the antifungal activity. Additionally, an atomic absorption result reveals that there are traces of metals detected such as Pb, Ag, Cu, Zn, and Mg. The antifungal activity was decreased as the concentrations were reduced. Accordingly, the present extracts may be used as the vital agents in the agricultural field to restrain the plant pathogenic fungi, especially F. oxysporum from a proliferation.

Management of Alternaria Leaf Blight in Pigeonpea through Host Plant Resistance and Micronutrient Application

Background: Pigeonpea [Cajanus cajan (L.) Millsp] is one of the primary grain legume crops grown in India for its high quality vegetable protein, animal feed and fodder. It is affected by various fungal and viral diseases. Among these, leaf blight caused by Alternaria alternata is one of the most destructive diseases and recently the disease of minor importance becomes major one in Tamil Nadu. Use of resistant cultivar is the most effective, economically viable and eco-friendly tool for combating the plant diseases. The micronutrients play a key role in many physiological and biochemical functions of the plants which influences plant pathogenic interaction. The micronutrients viz., Zn.Mn,Cu and Fe found to have greater impact on reducing the plant disease severity. Developing integrated disease management strategy involving disease resistant variety, micronutrient and fungicide application would be the best sustainable method for controlling the pigeonpea leaf blightMethods: Twenty four pigeonpea genotypes along with two local varieties viz., CO5 and CO6 were evaluated in the field for their resistance against Alternaria alternata leaf blight disease, consecutively for three years from 2015-16 to 2017-18 using the disease resistance scale ranging from 0 to 9. Field experiments were also conducted for three consecutive Kharif season from 2015 to 2018 to evaluate the efficacy of the foliar application of different micronutrients and combination fungicide viz., carbendazim 12% + mancozeb 63% on the incidence of leaf blight disease. Result: A total of 24 pigeonpea genotypes were screened for their resistance against leaf blight under field condition. Among these, four genotypes viz., BDN2, IPA 8F, IPA 15F and MA6 were found resistance and nine genotypes were moderately resistant and remaining 11 genotypes showed susceptible reaction to leaf blight. The results of the field experiment on micronutrient and fungicide application revealed that foliar spraying of MnSO 4 @0.2% on 30 days after sowing and carbendazim 12%+ mancozeb 63%@ 1g / lit on 45 days after sowing recorded the lowest leaf blight incidence of 8.1 PDI (Per cent Disease Index) with the highest disease reduction of 76.9% as against 35 PDI in the untreated control plot. The above treatments also recorded the highest grain yield of 905 kg/ ha as against 703 kg/ in the untreated control.

Titanium dioxide nanoparticles elicited agro-morphological and physicochemical modifications in wheat plants to control Bipolaris sorokiniana.

The current study involves the biogenesis of titanium dioxide nanoparticles (TiO2 NPs) by using Moringa oleifera Lam. aqueous leaf extract for the reduction of titanium dioxide salt into TiO2 nanoparticles. The biosynthesized TiO2 nanoparticles were observed by using the UV-visible spectrophotometry, SEM, EDX and XRD analytical methods. It was confirmed that the nanoparticles are crystalline and exist in the size range of 10–100 nm. The FTIR analysis confirmed the presence of O-H (hydrogen bonding), N-H (amide), C-C (alkanes) and C-I (Iodo-stretch) functional groups responsible for the stabilization of nanoparticles. Various concentrations (20, 40, 60 and 80 mg/L) of TiO2 NPs were applied exogenously on wheat plants infected with a fungus Bipolaris sorokiniana responsible to cause spot blotch disease at different time intervals. The measurement of disease incidence and percent disease index showed the time-dependent response and 40 mg/L was reported a stable concentration of TiO2 NPs to reduce the disease severity. The effects of biosynthesized TiO2 NPs were also evaluated for agro-morphological (leaf and root surface area, plant fresh and dry weight and yield parameters), physiological (relative water content, membrane stability index and chlorophyll content) and non-enzymatic metabolites (soluble sugar, protein, soluble phenol and flavonoid content) in wheat plants under biotic stress and 40 mg/L concentration of TiO2 NPs was found to be effective to elicit modifications to reduce biotic stress. The current study highlights the significant role of biosynthesized TiO2 NPs in controlling fungal diseases of wheat plants and thus ultimately improving the quality and yield of wheat plants.

Screening of rose genotypes for resistance against powdery mildew disease

A total of fifty five rose genotypes were screened against natural incidence of powdery mildew disease caused by Podosphaera pannosa, under a naturally ventilated polyhouse. Evaluation trial was conducted for two seasons during 2015-16 and 2016-17 to screen rose genotypes for their reaction to powdery mildew. The pooled apparent infection rate (r) of disease calculated for both seasons has showed a wide variation among genotypes. Based on per cent disease index (PDI), genotypes were categorized into different classes as tolerant (0-10 PDI), moderately tolerant (10.1-20 PDI), moderately susceptible (20.1-30 PDI) and highly susceptible (>40 PDI) to powdery mildew. Further, it was found that the accumulation of disease was low in case of moderately susceptible varieties compared to highly susceptible ones as indicated by the area under disease progression curve (AUDPC).

Assessment of Local Strain of Trichoderma asperellum Against Fusarium Spp

Trichoderma is unique fungus and now being most popular among the farmers as growth promoter and biocontrol agent. In present study local Trichoderma asperellum strain was evaluated against different Fusarium species in vitro and greenhouse conditions. In vitro study, Trichoderma asperellum was evaluated against 7 Fusarium species i.e., Fusarium oxysporum f. sp. ciceris, F. oxysporum f. sp. cubense (Tropical Race 1), F. oxysporum f. sp. cubense (Tropical Race 2), F. oxysporum f. sp. cubense (Tropical complex), F. oxysporum f. sp. lycopersici and Fusarium solani andpercentage reduction in the growth of these pathogens was ranged between 40.38 and 46.02%. This strainshowed strong antagonistic potential against F. oxysporum f. sp. lycopersici (73.91%)followed F. oxysporum f. sp. cubense race TR1 (64.49%), Fusarium udum (59.17),F. oxysporum f. sp. ciceris(58.33%), Fusarium solani(56.30%), F. oxysporum f. sp. cubenseTR 2(52.78%)and F. oxysporum f. sp. cubense TR (complex) 46.02%. In greenhouse study, Trichoderma asperellum was evaluated alongwith chitosan and botanicals against Fusarium oxysporum f. sp. lycopersici andminimum per cent disease index (PDI) was observed in treatment T4 (Seedling treatment with Trichoderma asperellum @ 5 g/lit + Chitosan @ 0.1% followed by its foliar spray) in which 44.66 per cent PDI recorded followed by T5 (Seedling treatment with Trichoderma isolate 8 @ 5 g/lit + Chitosan @0.1% followed by its foliar spray) in which 49.37 per cent PDI observed. The maximum per cent disease index was recorded in inoculated control (71.35%).

Field evaluation of different fungicides against Uromyces ciceris-arietini causing rust in chickpea in northern Karnataka

A field experiment was conducted to evaluate different fungicides against chickpea rust caused by Uromyces ciceris-arietini at Main Agricultural Research Station (MARS), Dharwad and ARS, Arabhavi during Rabi 2017 and 2018. The data on percent disease index and seed yield of chickpea for two years and two locations were pooled and revealed that, less percent disease index was observed in spray with Tebuconazole 50%+ Trifloxystrobin 25% w/w 75WG @ 0.5 g/l water and it was found effective in managing the disease with 15.81%. It was followed by Tebuconazole 25 EC @1.0 ml/l (16.60 %) and Propiconazole 25 EC @1 ml/l (18.06 %) and these are on par with each other. Highest percent disease index of 62.12 % was observed in untreated control. Seed yield of 12.38 q/ha was found in spray with Tebuconazole 50 %+ Trifloxystrobin 25% w/w 75WG @ 0.5 g/l water followed by 11.85 q/ha in spray with Tebuconazole 25 EC @1.0 ml/l water and 11.27 q/ha in spray with Propiconazole 25 EC @1 ml/l water. Minimum seed yield of 6.03 q/ha was found in untreated control.

Evaluation of Essential Oils against Early Blight (Alternaria solani) of Tomato

The fungicidal effect of some essential oils viz., Neem, Eucalyptus, Pongamia, Lemongrass, Thyme and Clove were evaluated against Alternaria solani causing early blight of tomato resulting in severe yield loss. All essential oil treatments showed the significantly varied antifungal activity against the pathogen. Among the in-vitro screened essential oils percent growth inhibition of pathogen was higher in Thyme oil (80%) and it was followed by Clove oil and Eucalyptus oil. Plant biometric observations viz., seed germination (84%) and seedling vigor (1747) was maximum with lower percent disease index (13%) was recorded in Thyme oil treated seeds and seedlings of tomato cultivar PKM 1.

Biocontrol agents against early blight (Alternaria solani) of tomato

Biological control agents are the best alternative to the hazardous chemical fungicides and other agro chemicals. Various biological control agents viz., Trichoderma viride, Pseudomonas fluorescens and Bacillus subtilis were evaluated against Alternaria solani (Ellis and Martin) Jones and Grout causing early blight of tomato resulting in severe yield loss. All treatments showed the varied antifungal activity against the pathogen. Among the in vitro screened biological control agents percent growth inhibition of pathogen was higher in Trichoderma viride (77%). Plant biometric observations viz., seed germination (89%) and seedling vigor (1994) was maximum with lower percent disease index (16%) was recorded in Trichoderma viride treated seeds and seedlings of tomato cultivar PKM 1.

Biocontrol potential of native Trichoderma spp. against anthracnose of great millet (Sorghum bicolour L.) from Tarai and hill regions of India

Sorghum anthracnose, caused by Colletotrichum graminicola, is a destructive disease, and increasing dependency on chemical fungicides for its control has serious environmental concerns since sorghum is fed to cattle. Thus there is a need to develop effective bio-pesticide for biological control of C. graminicola. Since Trichoderma is a proven biocontrol agent against plant pathogens, exploring the greater diversity that exists in Trichoderma, could be of notable economic significance in terms of disease control. To harness the hidden potential of Trichoderma strains against C. graminicola, a study was undertaken with 20 Trichoderma spp. isolated from 40 rhizospheric soil samples. Dual plate antagonism assay indicated the potential of T3, T4, T6, T15, and T19 isolates of Trichoderma against C. graminicola, with T3 isolate showing maximum (76.47%) mycelial growth inhibition. Molecular characterization based on the sequence analysis of ITS-rRNA and tef-1α genes identified these isolates as Trichoderma asperellum and Trichoderma harzianum. Under the glasshouse condition, biopriming of seed with Trichoderma spp. had significantly decreased the percent disease index to 32.92% and helped improve plant growth-promoting attributes compared to untreated control. Seed biopriming with T3 isolate exhibited higher antioxidant enzyme activities in terms of superoxide dismutase (36.63%), peroxidase (43.59%), and polyphenol oxidase (40.96%) at 48 h after pathogen inoculation. In most treatments, lignifications were highest in the epidermis, endodermis protophloem, metaphloem, pericycle, and protoxylem of sorghum roots after the 15th-day pathogen inoculation, indicating the strengthening of defense mechanism. To further evaluate, a field experiment was conducted for two consecutive years (Kharif season of 2018 and 2019) to test the best five isolates (T3, T4, T6, T15, and T19) against sorghum anthracnose. Lowest percent disease index of 54.90% and 53.68% and AUDPC value of 740.87 and 751.67 was reported from T. asperellum T3 bioprimed plants in the year 2018 and 2019, respectively, at 75 days after sowing. T. asperellum T3 isolate showed a significant increase in sorghum yield up to 22.22% and 27.29% higher than untreated control during the 2018 and 2019 Kharif season, respectively. This study indicated that T. asperellum T3 could be a potential biocontrol agent for managing the anthracnose of sorghum.

Efficacy of botanicals against Alternaria solani causing early blight of tomato

Tomato is one of the commercial vegetable crops, being affected with many diseases, among which early blight caused by Alternaria solani resulting in huge yield loss. As an alternative to the agro chemicals, botanicals were widely adopted owing to its eco friendliness. Several botanical extracts were prepared and screened against this seed borne pathogen. All treatment showed the varied antifungal activity against the pathogen. Among the screened botanicals percent growth inhibition of pathogen was higher in zimmu leaf extract (89%). Plant biometric observations viz., seed germination (94%) and seedling vigor (2383) was maximum with lower percent disease index (12%) was recorded in zimmu leaf extract treated seeds and seedlings of tomato cultivar PKM 1.

Performance Evaluation of Farmers’ Onion Varieties against Purple Blotch Disease

Aims: To evaluate the performance of farmers’ onion varieties against purple blotch disease at different locations and to correlate Percent Disease Index with yield attributing and other important traits.
 Study Design: Randomized Block Design, Field demonstration.
 Place and Duration of Study: National Innovation Foundation- India Gandhinagar Gujarat, Repoli and Palghar research stations of Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli Maharashtra during October 2017 to April 2019.
 Methodology: Two farmers’ onion varieties Sona-40 and Sandip were characterized and tested for their response against purple blotch disease under field condition in comparison with location-specific check varieties. Percent Disease Index of purple blotch was observed, compared and correlated with important traits viz. the plant height, leaves per plant, bulb diameter, maturity period, bulb weight, bulb yield and keeping quality. In Maharashtra areas, the study was conducted under Repoli and Palghar conditions during winter (Rabi) 2017, whereas at Gandhinagar Gujarat, it was undertaken in winter (Rabi) 2017 and 2018.
 Results: The farmers’ onion cultivars Sandip and Sona-40 were found to be tolerant to the purple blotch disease at all the locations. In Maharashtra and Gujarat, the average Percent Disease Index (PDI) in Sona-40 (12.1%, 12.2%) and Sandip (10.75%, 14.64%) was found significantly lower as compared to the checks respectively. The present studies also confirmed that onion bulb’s yield, weight and keeping quality were significantly correlated with the purple blotch disease.
 Conclusion: This study exhibited that the farmers’ onion varieties may perform better against disease infestation such as purple blotch disease. It also confirmed that the response of the onion varieties against purple blotch may vary in different locations. It is shown that the bulb weight, yield and shelf life of bulbs are significantly affected by purple blotch disease.

Silicon (Si) enhances the resistance in finger millet genotypes against blast disease

Finger millet (Eleusine coracana) leaf blast caused by Pyricularia grisea is a common disease and results in severe yield losses. Noble element silicon (Si) effectively mitigates both biotic and abiotic stresses and is known to enhance plant resistance against fungal and bacterial pathogens. The results revealed that there are potential positive effects of silicon application in soil to suppress the blast disease in finger millet genotypes. Among various treatments, 3 g calcium silicate/kg of soil was found to be most effective in enhancing resistance to blast followed by 2 g calcium silicate/kg of soil and 1 g calcium silicate/kg of soil treatments. Silicon content in leaf, stem, and root increased significantly over non-treated plants. A significant negative correlation was observed between silicon accumulation in the plants (leaf, stem, and root) and percent disease index. Both principal component analysis and cluster analysis revealed that among 40 genotypes tested, six genotypes such as ‘Suvra’, ‘GE-2740’, ‘NO-2836’, ‘GE-320’, ‘OEB-532’, and ‘GE-1135’ showed higher silicon accumulation with enhanced plant resistance along with the desired traits. Therefore, silicon accumulating genotypes can be used for the breeding program. Further, this study confirmed the positive effect of Si in enhancing the blast resistance in finger millets through the physical barrier mechanism by inhibiting the fungal penetration and colonization in cell and it can provide an alternative eco-friendly disease management strategy.

Integrated Management Practices for Clubroot Disease (Plasmodiophora Brassicae Wor.) of Cauliflower in Palung, Makwanpur, Nepal

Club root is one of the most important diseases in the eastern hills of Nepal affecting the rural income as well as quantity and quality of Cauliflower production. A field experiment was conducted in Randomized Complete Block Design (RCBD) with 5 treatments and 4 replications during February to May, 2019. The experiment was conducted in the Farmer’s field in the disease prone area of Thaha municipality-4, Palung of Makwanpur district to assess the efficacy of five different treatments; Nebijin, Hatake, Trichoderma viride, Lime and control for the management or suppressing the club root disease. The effectiveness of the treatments against club root disease was evaluated along with their influence on growth parameters and yield parameters of white top variety of cauliflower. Different parameters such as disease incidence, percent disease index (PDI) or disease severity index (DSI) and percent disease control (PDI) were recorded using disease scoring scale. The treatments showed significant effect on the yield and disease parameters, but not on the vegetative parameters of cauliflower. The lowest disease incidence (50.2%) and severity index (26.8%) and the highest percent disease control (57.6%) was recorded in Nebijin. Moreover, the Marketable yield (Mtha-1) per plot was observed highest from Nebijin (48.27Mtha-1) and Trichoderma viride (47.39 Mtha-1) treatment. From the study it may concluded that the application of Nebijin was more effective for the management of clubroot disease of Cauliflower and the use of Hatake and Trichoderma virideas bio-fungicides were also giving the potential assuring measure for the controlling disease of Cauliflower.
 SAARC J. Agri., 18(1): 87-98 (2020)

Bio-efficacy of tricyclazole 22.5% W/V + azoxystrobin 7.5% W/V against sheath blight disease of paddy

A new combination fungicide Tricyclazole 22.5% W/V (20.36% W/W) + Azoxystrobin 7.5% W/V (6.79% W/W) was tested against rice sheath blight diseases under field condition during Kharif 2015 and Rabi 2015-16. The combination fungicide Tricyclazole 22.5% W/V (20.36% W/W) + Azoxystrobin 7.5% W/V (6.79% W/W) at 1000 ml/ha was found effective against sheath blight diseases by recording least Percent Disease Index (PDI) of 14.44 during Kharif 2015 and 13.35 during Rabi 2015-16. Significant increase in grain yield (61.53 q/h) was also observed in the plots treated with Tricyclazole 22.5% W/V (20.36% W/W) + Azoxystrobin 7.5% W/V (6.79% W/W) at 1000 ml/ha in Kharif 2015 (61.53 q/ha) and Rabi 2015-16 (64.62 q/ha), whereas, other fungicide treatments recorded the yield in a range of 48.88 – 59.53 q/ha (Kharif 2015) and 46.26 – 61.28 q/ha (Rabi 2015-16).

Screening of Maize (Zea mays L.) Germplasms for resistance against Turcicum Leaf Blight (TLB) under field conditions

Maize is the leading cereal worldwide with wide adaptability and higher productivity potential. It has notable productive potential among the cereals. It is the third most important grain crop after wheat and rice. Turcicum leaf blight (TLB) affects the maize crop from the seedling stage to maturity. The present study involved field evaluation of 335 maize entries for resistance against TLB disease under artificially inoculated field conditions in RBD using with a check at Agricultural Research Station, Karimnagar during rabi 2018-2019 and kharif, 2019. Among 92 lines, 84 lines were categorised as resistant, Five lines were moderately resistant, two lines were moderately susceptible and CM -202 recorded 70.33% percent disease index (PDI), which is highest during Rabi 2018-2019. Out of 243 lines, 12 lines were categorised as resistant, 129 lines were recorded as moderately resistant,28 lines were noticed moderately susceptible and two lines viz., IB-98 and IB-103 observed with high PDI and severely affected by TLB and rated as susceptible during Kharif-2019.