Mohammad Ashraf Ahanger

Leaf blight disease of maize was observed during a field survey of Karnataka and Maharashtra in 580 and 360 ha areas, respectively, conducted in the Kharif season of 2020 at V3 to V7 growth stages. The symptomatic plants showed grey to brown spindle-shaped spots. Four fungal isolates (Ero_DWD-27, Ero_DWD-20, Ero_Mya-1 and Ero_Rri-1) were obtained. Isolation used standard tissue culture on PDA, followed by single spore purification (Johnston and Booth 1983). Microscopic observations of pure cultures revealed spore characteristics resembling Exserohilum rostratum. The isolation process was repeated on the same symptomatic leaves from the original locations, confirming morphological and cultural similarity to E. rostratum despite typical turcicum leaf blight symptoms. Pathogenicity was confirmed via whole-plant inoculation on susceptible maize, fulfilling Koch's postulates. The characteristic symptoms on leaves first appear as yellowish, water-soaked spots, progressing to spindle-shaped necrotic lesions. Single-spore cultures' morphological and cultural characteristics revealed their resemblance to E. rostratum. Conidia were dark brown, straight to slightly curved (48.28-65.35 x 12.24-15.84 µm), with six to seven septa and a prominent hilum. Conidia developed with six to seven septa, including two terminal dark and thick septa (Lin et al. 2011). The conidiophores were septate, light to dark brown, geniculate, single or in groups of 2-6, and measured about 140-350 x 6-14 µm in size. Colony color varied on PDA after 14 days, from dark grey to greyish white with circular or filamentous growth forms and mostly regular margins. Molecular identification used ITS, β-tubulin, and LSU regions amplified with standard primers (White et al. 1990; Kroon et al. 2004; Fliegerová et al. 2006; Manzar et al. 2022; Anwer et al. 2022). Sequences were deposited in GenBank (NCBI) under accession numbers PQ394595-PQ394596 and PQ408655-PQ408656 (ITS), PQ432870-PQ432871 and PQ438739-PQ438740 (β-tubulin), and PQ300560, PQ373037, PQ373042, and PQ375114 (LSU). BLAST analysis confirmed the high similarity of isolates Ero_DWD-27, Ero_DWD-20, Ero_Mya-1, and Ero_Rri-1 to E. rostratum. A maximum-likelihood phylogenetic tree based on combined ITS, β-tubulin, and LSU sequences corroborated this identification. Based on colony and morphological characters, pathogenicity, and confirmation at the molecular level, the isolated fungal isolates were identified as E. rostratum. Although E. rostratum has been reported to cause the leaf spot on maize in Henan, China (Xie et al. 2022). To our knowledge, this is the first study of E. rostratum causing maize leaf blight in India. The study underscores the need for accurate pathogen identification and management, as maize is India's third major cereal.

Background: Rapeseed is an important edible oilseed crop around the globe, cultivated across different agro ecologies. In Kashmir valley the difference in the productivity of rapeseed realized at farmers field and its potential yield is tangible. In this context present study was carried out to demonstrate the impact of good agricultural practices (GAP) on rapeseed crop at farmer’s field, employing frontline demonstrations (FLDs). Methods: The study on FLDs was conducted on rapeseed crop over a period of five years from 2017-18 to 2022-23 covering an area of 180 acre of agricultural land. Three newly released high yielding varieties following recommended package of practices were evaluated at farmer’s field against the farmers own practice of rapeseed cultivation. Comparison among the treatments was tested at 5% level of significance employing student’s ‘t’ test. Result: Transfer of technology at farmers field witnessed a significant enhancement in the seed yield through improved practice (1151 kg ha-1) compared to farmers practice (983 kg ha-1) with an average yield advantage of 17%. The investigation also revealed varying extension and technology yield gaps ranging between 158 to 174 kg ha-1 and 317-637 kg ha-1, respectively. These findings underscored significant role of adopting improved practices in enhancing the seed yield. Technology index of 31% reflects the sensitivity and the urgent need for more cohesive endeavours aimed at dissemination of improved technology at farmer’s field. The adoption of improved practice yielded additional gains (`2088 ha-1), higher gross returns (`52339 ha-1) and benefit: cost ratio (1.92).

Wheat is highly affected by stripe rust disease, particularly under cooler environments, and the losses can reach up to 100 percent depending on the intensity of infection and the susceptibility of the genotype. The most effective method to manage this disease is the use of resistant varieties. In the present study, 192 wheat genotypes were evaluated for stripe rust resistance under field conditions and also in a laboratory using molecular markers. These lines included pre-breeding germplasm developed for rust resistance and some high-yielding commercially grown wheat varieties. Out of 192 genotypes, 53 were found to be resistant, and 29 showed moderate resistance reaction under field conditions, whereas the remaining genotypes were all either moderately susceptible or susceptible. Under controlled conditions, out of 109 genotypes, only 12 were found to be resistant to all the six virulent/pathogenic pathotypes. Additionally, a selection of 97 genotypes were found resistant in field screening and were subjected to molecular validation using the markers linked to major R-genes, viz., Yr5, Yr10, Yr15 and Yr17. Nine genotypes possessed the Yr5 gene, twelve had the Yr10 gene, fourteen had the Yr15 gene and thirty-two had the Yr17 gene. The resistance genes studied in the current study are effective in conferring resistance against stripe rust disease. The genotypes identified as resistant under both field and controlled conditions can be used as sources in stripe rust resistance breeding programs.

Sheath rot is one of the most destructive emerging diseases of rice in Asia and a significant loss (20–85%) to rice production is caused by this disease under temperate agro-climatic conditions of Kashmir. Disease is more prevalent in higher belts of valley where Japonica rice cultivation is more common. Also, late-maturing varieties are more likely to be attacked by sheath rot disease of rice. Information regarding the occurrence and distribution of any pathogen and its variability in the field is very much essential to devise a suitable disease management programme against the particular pathogen. The isolates of Sarocladium oryzae tested in the present study exhibited considerable variation in cultural characteristics, morphology and pathogenicity. The resistant sources for sheath rot disease of rice were identified among the temperate germplasm of rice under a relatively high inoculum concentration and disease pressure of all the variable isolates of S. oryzae. Among 219 rice genotypes screened for resistance against S. oryzae under field conditions, 42 genotypes were further evaluated under controlled epiphytotic conditions against all the 18 isolates of S. oryzae. Four genotypes (SKUA-354, ORN-V4, GS-183, GS357) were finally selected with high resistance against sheath rot disease of rice which can be utilized as potential donors for the development of disease-resistant varieties of rice against sheath rot.

In August 2020 powdery mildew was observed on pear cv. Fertility at the University research field in Shalimar, Srinagar (J&K), India (34° 08' 30.5'' N and 74° 51' 42.0'' E) with a disease incidence...

Rice is globally the most important food crop and there is a dire need to feed the ever-increasing population by improving its productivity. It has been realised that diseases are the major impediment towards enhancing the productivity of this crop. Despite the advent of modern effective disease control measures such as use of chemicals, bioagents and resistant varieties; agronomic practices still play a vital role in disease management in rice. Optimum use of different agro-techniques can be exploited for efficient control of various devastating diseases like rice blast, sheath blight, bakanae and many more by providing a favourable environment to better crop survival. Besides, appropriate selection of a variety, use of quality seed, method of establishment, planting time, nutrient, water and weed management practices can be well exploited to control various diseases. This manuscript entails to review the work pertaining to use of agronomic practices for exploiting the potential of crop environment interaction through reduced disease infection and to bridge the yield gap for ensuring sustained food security.