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Sorghum (Sorghum bicolor [L.] Moench) is one of the top ten cereal crops in the world and is grown for fodder and seed purposes. During the fall of 2019 to 2022, a disease causing small to long streaks on leaves was observed in sorghum fields of Hisar (29° 9' 6.6996'' N, 75° 43' 16.0428'' E), Rohtak (28° 53' 43.8540'' N, 76° 36' 23.8068'' E) and Mohindergarh (28° 16' 6.0492'' N, 76° 9' 3.3552'' E) regions of Haryana between July and October. The reddish brown streaks were observed in the interveinal spaces of upper and lower leaves. The disease incidence reached 20-30% of plants in affected fields. The diseased leaf tissues were disinfected with 70% alcohol and placed in a tube with sterile water. After 30 minutes, 100 µl of the suspension was inoculated onto nutrient agar medium, incubated at 28 ± 2°C for three days, and a pure culture was obtained by restreaking on nutrient agar (Janse, 2005). The rod-shaped gram-negative bacterium with round, cream to white colonies was positive for methyl red, citrate utilization, urease activity, and glucose, lactose, sorbitol, rhamnose and sucrose fermentation tests. The genomic DNA of the bacterial suspension was extracted and 16S rDNA was amplified using universal 27F/1492R primers (Marchesi et al. 1998), resulting in tentative identification as Klebsiella sp. It was further confirmed with PCR amplification of Klebsiella specific primers (F:5ʹ-CGCGTACTATACGCCATGAACGTA-3ʹ; R:5ʹ-ACCGTTGATCACTTCGGTCAGG-3ʹ) for gyrA gene (Brisse and Verhoef 2001). Discrete PCR amplicons of 1,500 (16S rDNA) and 300 bp (gyrA) were observed in a 1% (w/v) agarose gel. Forward and reverse DNA sequencing of both amplicons of the Hisar isolate (VMKV101) was carried out using a BDT v3.1 Cycle sequencing kit and consensus sequences were generated by using the program SeqMan Ultra (DNASTAR Lasergene). Sequences of the PCR products were deposited in GenBank with accession numbers MZ569433 (16S rDNA) and OP390080 (gyrA). The 16S rDNA sequence was 97.32% similar to K. variicola strain 13450 (CP026013; 1,450/1,490 bp) and the gyrA sequence had 99.66% similarity to K. variicola strain FH-1 (CP054254; 297/298 bp). A 16S RNA-based phylogenetic tree done by MEGA11 (Tamura et al. 2021) using the Maximum Likelihood method showed that strain VMKV101 clustered with K. variicola type strain F2R9. The complete bacterial genome (GCA025629215), sequenced by the Ion GeneStudio S5 system using Ion 530 chips (Thermo Fisher Scientific), was 99.03% identical by average nucleotide identity (ANI) to the type genome (CP045783) of Klebsiella variicola, with 87.8% genome coverage. For pathogenicity testing, a bacterial suspension (10 ml, 1×107 colony forming units/ml) was injected into the whole whorl after mechanical injury on 15-20 days old seedlings of the susceptible genotype HC-171, then plants were incubated at 35 ± 2°C, >80% relative humidity. Control plants were injected with sterile distilled water. Initial symptoms were observed on leaves of inoculated plants after 5 to 7 days as narrow, small longitudinal reddish brown streaks. As the disease progressed, the streaks on the leaf blade increased in number and size maintaining the reddish brown color. These streaks had slightly wavy margins and were surrounded by bright yellow halos. After 15 to 20 days, the streaks were 0.5 to 2.0 mm wide and 1.0 to 5.0 cm long, occasionally up to 10.0 cm long on both side of the leaves. Over time, neighboring streaks coalesced to form large necrotic areas. All inoculated plants exhibited identical symptoms. No symptoms were observed on control leaves. The reisolated bacterium from diseased sorghum leaves showed exactly the same morphological, biochemical and 16S RNA and gyrA molecular characteristics. To our knowledge, this is the first report of K. variicola causing a leaf streak disease on sorghum. Klebsiella species primarily cause diseases in humans and animals, but K. variicola has been found to incite banana soft rot (Fan et al. 2015) and K. aerogenes to cause stem rot in pearl millet (Malik et al. 2021). Differences of prevalence, spread and control between K. variicola and two other bacteria (Xanthomonas vasicola pv. holcicola causing Bacterial leaf streak; Paraburkholderia andropogonis causing Bacterial leaf stripe) causing leaf streak diseases on sorghum need to be determined. The identification of Klebsiella leaf streak disease lays the groundwork for future investigations into epidemiology and management of K. variicola on sorghum.

Organic agriculture has been coming up as one of the promising segments of crop production systems in India. There are numerous reasons for it, however; human health, sustainable environment, soil health, etc. are the important ones. As per the latest information, India has about 1.5% of total cultivable land under organic agriculture. The occurrence of plant diseases in this crop production system is one of the limiting factors. For the management of plant diseases in organically grown crops, there are limited resources since there is a restriction on the use of synthetic fungicides. Under such a situation, bio-pesticides have the potency to take care of plant diseases. Although there are certain fungal and bacterial candidates well efficient in controlling diseases, genus Trichoderma has occupied a prestigious position among them. It is capable of managing seed and soil-borne plant diseases. Presently it is available in wettable powder (WP) and liquid formulations in variable concentrations for the application.

Objectives: Under All India Co-ordinated Research Project on Potato, studies on the selection of potato apical leaf curl virus disease-resistant genotypes, pest surveillance, seed degeneration, and management of aphid in field conditions were conducted at Hisar during 2017–2018. Methods: Sowing of seed tubers was done at recommended time and spacing in every experiment followed by spraying of required insecticides. Observations on different aspects were recorded and statistically analyzed to present results in tabular format. Results and Discussion: Out of 100 germplasm, seven were resistant and one was moderately resistant to potato apical leaf curl New Delhi virus, all the local genotypes were susceptible to disease. There was infestation of aphids, jassids, thrips, and whitefly irrespective of cultivars. Severe mosaic incidence ranged from 63.6 to 93.2%. The breeder seed was superior as it resulted in the highest seed tuber emergence (98.94%) and the least incidence of leafroll disease (0.80%) followed by seed tuber of seed plot technique (SPT). The conventional seed performed the poorest in terms of emergence and exhibited the highest disease incidence. Aphid appeared in the 47th meteorological week and it approached the ET level in the 52nd week. Whitefly population was the highest in the 47th week which continuously declined. Jassid population was very mild and thrips appeared in the 52nd week. Flonicamid 50 WG caused higher aphid mortality than imidacloprid after 24 h of spray. The maximum and minimum temperatures varied from 16.9 to 35.7 and 2.6 to 16.2° C, respectively. The morning and evening relative humidity was in the range of 82–100 and 24–75%, respectively. The wind speed ranged from 1.0 to 3.6 KMPH and the sun was shined from 0.3 to 7.6 h. The results of this study are close conformity of earlier researchers. Conclusion: It is concluded that resistant genotypes, breeder seed, and seed produced through SPT are promising in managing the disease successfully. Flonicamid is a good alternative of imidacloprid. Aphid is a major pest that plays a key role in transmitting viral disease of this crop, its population touched ET level in the 52nd week.