Biological and molecular evidences on host range of leaf curl begomovirus disease of sunflower (Helianthus annuus L.)

The present study was conducted to identify the alternate hosts of new leaf curl virus disease of sunflower. In the present study several crops and weed hosts were cross inoculated with leaf curl virus of sunflower under laboratory through insect vector whitefly (Bemisia tabaci), further all inoculated samples were retested (3-4 weeks after inoculation) by molecular based Polymerse chain reaction diagnosis for the presence of virus. The results revealed that the causal virus of the disease was successfully transmitted from sunflower to sunflower (Helianthus annuus), tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum L) and weed hosts such as Acanthospermum hispidum, Amaranthus viridis and Parthenium hysterophorus in a short incubation period (2-3 weeks after inoculation), while on other hosts Chilli (Capsicum annuum L) and Datura stramonium, infection occurs in delayed incubation period. Further molecular analysis thorough polymerase chain reaction (PCR) diagnostic technique using virus specific primers also confirmed the presence of coat protein (CP) of leaf curl begomovirus invirus inoculated hosts viz., chilli, sunflower, tomato, and tobacco and weed hosts such as Acanthospermum hispidum, Amaranthus viridis, Datura stramonium and Parthenium hysterophorus. Thus, findings substantiate that the above hosts are major sources of the virus inoculum and served as potential alternate hosts of the disease during the off season

Studies on Symptomatology, Morphological and Molecular Characterisiation of Erysiphe cichoracearum Causing Powdery Mildew of Okra

Okra (Abelmoschus esculentus (L.) Moench) is a globally important annual vegetable belongs to family malvaceae, it is most broadly distributed vegetable all over the world. Among the fungal diseases affecting okra crop, powdery mildew caused by Erysiphe cichoracearum DC. is the most important disease causing considerable yield losses. The disease was characterized by the appearance of small white powdery specks on upper surface of the lower leaves which enlarged and coalesced forming bigger patches. Later on the disease spread to the upper leaves, coalescing of the white powdery specks and enlargement in their size ultimately resulted in complete coating of white fungal mass on the leaves. The morphological studies of the pathogen in the laboratory revealed, that the mycelium is septate, ectophytic, hyaline and adjacent to the mycelium, basal septum of the conidiophores was seen. The conidiophores were erect, on which conidia were produced either singly or in short chains. The conidia were found cylindrical or barrel in shape, hyaline, non-septate and measured 75.23 µm x 40.65 µm. Molecular characterisation of the native isolate resulted in the DNA amplicon at the region 531 bp. Further, DNA sequence was obtained for ITS Rdna and was deposited in NCBI gene bank. Accession number ‘MW774352’ was obtained and it was confirmed that the causal pathogen of okra powdery mildew of Raichur region is Erysiphe cichoracearum

Screening of Okra Genotypes against Powdery Mildew under Natural Epiphytotic Conditions

Okra (Abelmoschus esculentus (L.) Moench) is a globally crucialannual vegetable belonging to family malvaceae, it is the most broadly distributed vegetable all over the world. Among the fungal diseases affecting okra crops, powdery mildew caused by Erysiphecichoracearum DC. is the most crucial disease-causing considerable yield losses. Host plant resistance is one of the most practical, economical and feasible methods of management of plant diseases. An attempt was made to identify sources of resistance which could be used in developing resistant variety to mitigate loss in farmer’s field.Fifty okra genotypes were screened for their response to powdery mildew under natural epiphytotic conditions during Rabi, 2020-21Results revealed that, out of fifty genotypes screened, none of them showed immune and resistant reactions to powdery mildew. However, one genotype i.e., EC329404 showed a moderately resistance reaction. Twenty genotypes showed a moderately susceptible reaction. While twenty-two genotypes showed susceptible reaction, and one genotype viz., IC42531 showed a highly susceptible reaction. The average ‘r’ value ranged from 0.070 to 0.123. The highest average ‘r-value (0.123) was observed in genotypes IC42524 and EC329405, with the least average ‘r’ value in genotype EC329415 (0.070). For yield, It was found that most of the genotypes screened were potential yielders and recorded good yield despite the pathogen attack. Thus these high-yielding genotypes can be utilised in back cross-breeding along with disease resistant parent (EC 329404) to obtain resistant variety with high-yielding potential

Efficacy of Fungicides and Commercially Available Organic Products against Blight of Cotton Caused by Alternaria macrospora

An attempt was made to test available formulation of fungicides and commercially available organic products for their efficacy under laboratory condition, an experiment was carried out at Department of Plant pathology, Raichur, Karnataka, India by using poison food technique. Among the commercially available organic products tested, fatty alcohol and diluents has recorded significantly higher mycelial inhibition of 100 per cent at the concentration of 5 and 10 per cent. In case of contact fungicides propineb 70% WP, metiram 70% WP and mancozeb 75 % WP recorded 100 per cent mycelial inhibition, with respect to systemic fungicides hexaconazole 5% EC, propiconazole 25% EC and difenoconazole 25% WP and among the combi fungicides azoxystrobin 8.3% + mancozeb 66.7% WG were most effective in 100 per cent inhibition of mycelial growth of Alternaria macrospora over the control. The commercially available organic product fatty alcohol and diluents, propineb 70% WP, hexaconazole 5% EC, propiconazole 25% EC and azoxystrobin 8.3% + mancozeb 66.7 % WG were found to be effective against inhibition of mycelial growth of Alternaria macrospora

Correlation of Weather Variables on Emergence of a Virus Disease Bud Necrosis Disease of Greengram Incited by Soybean Yellow Mottle Mosaic Virus at Raichur, Karnataka

Greengram [(Vigna radiata (L.) Wilczek] is the important pulse crop after chickpea and pigeonpea cultivated in India which is called as “Queen of pulses”, the crop is proned to be infected by many fungal and bacterial diseases. In recent years emergence of a virus disease bud necrosis of greengram was noticed in Raichur and the incidence of disease gradually increased in greengram growing areas of Karnataka. Incidence of bud necrosis disease of greengram and correlation with weather factors was studied during Kharif 2021 at research plot and MARS, UAS, Raichur, Karnataka. The study reveals that, on all four dates of sowing (25th June, 1st July, 9th July and 23rd July 2021), disease was initiated at 25 DAS and highest disease incidence was observed at 75 DAS. The peak activity of thrips was noticed during August month. The weather variables viz., maximum temperature was more than 32 °C, minimum temperature was more than 22°C, rainfall was less than 19 mm/day, morning relative humidity was less than 91 per cent, evening relative humidity more than 44 per cent, evaporation 4.3 mm/day and sunshine hours less than 6 hr/day was favorable for bud necrosis disease in four dates of sowing. Whereas, morning relative humidity, evening relative humidity and age of the crops were having positive relationship with progress of bud necrosis on all four dates of sowing. Thrips and rainfall showed  a positive correlation with disease incidence in all dates of sowing except the fourth date of sowing

Influence of Weather Parameters on the Incidence and Severity of Guava Scab Caused by Pestalotiopsis psidii (Pat.)

Guava (Psidium guajava) is an important tropical fruit crop of India and is known as “apple of the tropics”. It is grown and utilized as an important fruit in tropical countries like India, Indonesia, Pakistan, Bangladesh and South America. Among the biotic and abiotic diseases of guava, guava infected by scab disease [Pestalotiopsis psidii (Pat.) Mordue] is an economically important and reported average yield losses in the range of 12-18%. An experiment was conducted during 2023 at Horticulture garden, Main Agricultural Research Station, University of Agricultural Sciences, Raichur during 2023 to understand the influence of various weather parameters on the guava scab disease development. The results revealed that, irrespective of the varieties, interaction among maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity, rainy days and rainfall showed significant positive correlation with guava scab disease. And the incidence and severity of guava scab was found to be 23.21, 56.00 (Allahabad Safed), 32.45, 68.50 (Lucknow 49) and 85.00, 74.51 (Arka Kiran) respectively

Influence of Different Culture Media on Growth and Sporulation of Colletotrichum capsici

Aim: To know the best culture media for growth and development of Colletotrichum capsici causing chilli anthracnose. Study Design: Twelve different culture media were selected and three replications were maintained. Place and Duration of Study: Department of Plant Pathology, University of Agricultural Sciences, Raichur, Karnatka, which was carried out in the year 2021-2023. Methodology: The laboratory study was conducted to know the best nutrient media for the growth and sporulation of the pathogen. The pathogen was isolated from infected chilli fruit using tissue isolation technique and pure culture was maintained. Twelve different nutrient media were selected and tested for the growth and sporulation of the pathogen in three replications. Results: Among twelve media tested, Red chilli dextrose agar have promoted the maximum growth of C. capsici (90.0 mm), which was followed by carrot dextrose agar and potato carrot agar (89.50 mm). Green chilli extract agar significantly promoted minimum growth of C. capsici (33.50 mm), which was followed by red chilli extract agar (48.00 mm) and Sarbouraud’s agar (48.50 mm). The cultural characters were varied among the media. Conclusion: Potato dextrose agar and carrot dextrose agar media were proved to be best media for growth and sporulation of Colletotrichum capsica

Enhancing Germination and Seedling Vigour of Interspecific F1 Hybrid Chilli Seeds through Priming with KNO3 and GA3

India is called a home for spices and also involved in the export. Chilli is an indispensable spice, essentially used in every Indian cuisine due to its pungency, taste, appealing odour and flavour. Quality seed is a key component for the successful agriculture, where the main objective is each seed should germinate and produce a vigorous seedling which ensures higher seed yield, productivity and also better storability to achieve good yield in the coming season. To achieve all the above said traits, the seed technologists have developed seed enhancement techniques. Seed enhancement techniques are post-harvest treatment of seeds to enhance the seed germination and seedling growth by facilitating the delivery of seeds with other materials at sowing time. This enhancement technique includes hydration treatments like seed priming and seed encapsulation like seed pelleting, which impacts significantly on seedling emergence and establishment. In this experiment study was conducted different priming treatments, seeds primed with KNO3 @ 1%, 2% and 3% and seeds primed with GA3 @ 50 ppm, 100 ppm and 150 ppm, the seeds treated with KNO3 @ 1% showed highest germination percentage, root, shoot, seedling length, seedling dry weight and seedling vigour index I and II which was followed by GA3 @ 50 ppm. Acknowledge of proper priming techniques in order to improve the germination in the seeds