Morphological, cultural and pathogenic variability in Alternaria brassicae, the causing agent of black spot of rapeseed and mustard

The study on pathogenic diversity of twenty isolates of Alternaria brassicae collected from different locations of Uttarakhand and Central Uttar Pradesh infecting Brassica species (Brassica rapa, Brassica juncea and Eruca sativa) revealed that there was a distinct difference among isolates in terms of mycelial growth, spore length, width, spore beak length and width. The average spore length varied from 21.23?m to 38.13?m with minimum of isolate AUA-19, AUA-43 i.e 21.23?m and maximum of AUA-47 i.e. 38.13?m . The isolates tested on Brassica juncea var.Varuna in green house conditions revealed that all the twenty isolates behaved differently. Among all the isolates, Brassica juncea isolates i.e. AUA-25, AUA-39, AUA-41, AUA-47, AUA-19, AUA-24, AUA-22, AUA-21, AUA-31, AUA-43 and AUA-45 from Uttarakhand, and AUP-29 from Central Uttar Pradesh can be grouped into highly pathogenic with range of Alternaria spot size i.e. 5.03-8.30mm in diameter, while isolate of Eruca sativa i.e. AUA-38 was found least pathogenic with 1.63mm in dia. and eight isolates AUA-18, AUA-20, AUA-23, AUP-28, AUA-32, AUA-33 and AUA-36 were found moderately pathogenic. This study will be useful in developing integrated management strategies of Alternaria leaf spot and breeding programs of oilseed crops (Brassica sp.)

Synergistic analysis of satellite, unmanned aerial vehicle, terrestrial laser scanner data and process-based modelling for understanding the dynamics and morphological changes around the snout of Gangotri Glacier, India

The glaciated areas of the Himalaya often experience mass movement, glacial lake outburst flood and other associated hazards, posing threat to the communities and infrastructure in the downstream areas. A large debris flow occurred during July 16–19, 2017 near the present snout of the Gangotri Glacier in the Garhwal Himalaya, India resulting in significant geomorphological changes in the vicinity. The present study assesses the applicability of multi-source remote sensing data from satellites, unmanned aerial vehicle (UAV) and terrestrial laser scanner (TLS) along with process-based modelling to understand and quantify glacier snout dynamics and morphological changes around Gangotri Glacier in the Garhwal Himalaya of India.Weshow that retreat rates of Gangotri Glacier snout along the lateral flow lines are (left flowline 29.6m year−1; right flowline 60.5 m year−1) are significantly higher compared to the central flow line (18.2myear−1) during2010–2020 leading to total loss in glacial ice area of 0.11 ± 0.015 km2. The snout dynamics and evolution of the new channel from the terminus of the adjoining Meru Glacier, connecting the moraine-dammed glacial lake and the Bhagirathi River, suggest that retreat of the Gangotri Glacier, intense precipitation and excessive seepage from the glacial lake were the important drivers of the debris flow in July 2017. The accumulated debris occupied an area of ~0.25 km2 near the snout of the Gangotri Glacier and shifted Bhagirathi River by 36–200 ± 9.35m towards northeast. The synergistic analysis of pre- and post-event satellite, UAV and TLS-based digital elevation models (DEMs) and satellite images indicate that about −8±0.066Å~106m3 of sediments were generated by the debris flow. The results from remote sensing data suggest that a significant portion (~60%) of the deposited debris has been transported to the downstream areas between July 16–19, 2017 and October 2, 2017. Regular monitoring of the area is recommended, especially in light of climate change using earth observation data and ground measurements. The multi-source integrated framework implemented in this study is generic and can be applied for any debris flow or landslide studies in glaciated terrain.</p