Important field crops of northern Karnataka viz., Sugarcane, Cotton, Maize, Chickpea, Sunflower and Soybean suffer from many insect pests and diseases. During 2014-15 cropping season, a software (e-SAP: electronic Solutions Against Agricultural Pests) was made use to record observations on important insect pests and diseases on these crops following roving survey in six Districts of northern Karnataka. All the information about the selected farmers was recorded through field devices (Tablets) which were preloaded with e-SAP software. Based on the observations recorded, maximum infestation of root grub, early shoot borer and wooly aphid in sugarcane; miridbug and aphid in cotton; aphid and pink stem borer in maize; gram caterpillar in chickpea; spodoptera in soybean and leaf hopper and Bihar hairy caterpillar in sunflower was noticed. Maximum incidence/severity of rust and ring spot diseases in sugarcane; grey mildew, rust and angular leaf spot in cotton; turcicum and maydis leaf blight in maize; wilt and root rot in chickpea; Alternaria leaf spot and rust in soybean and necrosis and rust in sunflower commonlyoccurred in the six crops. Some newly emerging problems viz., wire worm, root aphid, yellow leaf disease, pokka boeng in Sugarcane; midge fly in cotton; Banded leaf and sheath blight in maize recorded. Important advisories for management provided were soil drenching of chlorpyriphos 20EC @ 10ml/l. or soil application of Metarhizium anisopliae @ 12.5 to 25 kg + FYM 1250 kg / ha for sugarcane root grub; spraying of fipronil 80WG 0.1g/l of water for cotton sucking pests; seed treatment with Trichoderma harzianum @4g/kg or spot drenching with carbendazim 50WP @1g/l for chickpea wilt / root rot and use of resistant cultivar (DSB-21) or spraying of hexaconazole @1.0 ml/l35-45 days after sowing for soybean rust. Four out of ten farmers interviewed, expressed satisfaction for receiving timely advisories and realized 4-5% increase yield in sugarcane, cotton and chickpea. Thus real time surveillance through ICT tools has helped for plant protection measures at appropriate period.

Cotton bacterial blight caused by Xanthomonas citri subsp. malvacearum (Xcm) is one of the most widely distributed and devastating diseases of cotton (Gossypium spp.) worldwide. Twelve Xcm races have been described in the world, with their relative prevalence varying by country. This study aimed to determine the current frequency and distribution of Xcm races in Brazil. Leaves showing cotton blight symptoms were collected from 12 cotton producing areas in the states of Bahia, Goiás, Mato Grosso and Mato Grosso do Sul. A total of 92 isolates were collected from surveyed areas. Race identification was performed by injection of bacterial suspensions into 10 differential cotton cultivars (Acala 44, Stoneville 2B-S9, Stoneville 20, Mebane B1, 1-10B, 101-102B, Gregg 8, Empire B4, PDX P4 and S-295). All Xcm isolates were characterized as race 18, indicating this to be the prevalent race in Brazil.

Cotton bacterial blight caused by Xanthomonas citri subsp. malvacearum (Xcm) is one of the most widely distributed and devastating diseases of cotton (Gossypium spp.) worldwide. Twelve Xcm races have been described in the world, with their relative prevalence varying by country. This study aimed to determine the current frequency and distribution of Xcm races in Brazil. Leaves showing cotton blight symptoms were collected from 12 cotton producing areas in the states of Bahia, Goiás, Mato Grosso and Mato Grosso do Sul. A total of 92 isolates were collected from surveyed areas. Race identification was performed by injection of bacterial suspensions into 10 differential cotton cultivars (Acala 44, Stoneville 2B-S9, Stoneville 20, Mebane B1, 1-10B, 101- 102B, Gregg 8, Empire B4, PDX P4 and S-295). All Xcm isolates were characterized as race 18, indicating this to be the prevalent race in Brazil.

Abscission of flowers, squares and bolls is an important problem which causes considerable lint yield loss in cotton. This problem needs to be addressed to obtain optimal yields. Abscission can be regulated by manipulation of the environment or by application of chemicals. The factors, like moderate temperature, moderate water supply, normal light intensities, adequate mineral nutrients, freedom from diseases and insects tend to prevent or delay abscission. Growth retardants, like mepiquat chloride (MC) and cycocel (CCC) reduce internode length, thereby, reducing plant height and stimulating the translocation of photosynthates towards sink. MC 50 ppm sprayed at 90 DAS (days after sowing) resulted in significantly higher yield (11.9 %) over control. Late opening of mature bolls is also one of the major factors limiting crop productivity. Cotton hybrids usually attain excessive vegetative growth and thick crop canopy with poor boll opening especially when crop encounters low temperature at maturity. The use of chemical defoliants has been reported to enhance boll opening without affecting the seed cotton yield. Ethephon and thiadiazuron application at 60% boll opening stage increased the shedding of leaves, boll opening and seed cotton yield.

ABSTRACT Cotton monoculture favors the development of diseases such as ramularia leaf spot, which causes early defoliation and boll rotting, thus decreasing yield. This study aimed at evaluating the severity of ramularia leaf spot and its effects on cotton leaf area and yield. The experiment was conducted in a triple (4 x 3 x 2) factorial design, consisting of four cultivars (FM940GLT, FM944GL, TMG42WS and TMG43WS), three thirds of the plant (lower, middle and upper) and two management conditions (with and without fungicide application). To the variable area under the disease progress curve, the lowest values were observed in the upper third of the TMG42WS and TMG43WS cultivars, with the lower and middle thirds presenting the highest severity. The condition managed with fungicide and the upper third showed the lowest values for area under the disease progress curve. The leaf area was negatively affected by the ramularia leaf spot. Concerning the seed and fiber yields, the highest averages were observed for the middle third and the condition managed with fungicide. There was no statistical difference for cotton yield loss.

Cotton monoculture favors the development of diseases such as ramularia leaf spot, which causes early defoliation and boll rotting, thus decreasing yield. This study aimed at evaluating the severity of ramularia leaf spot and its effects on cotton leaf area and yield. The experiment was conducted in a triple (4 x 3 x 2) factorial design, consisting of four cultivars (FM940GLT, FM944GL, TMG42WS and TMG43WS), three thirds of the plant (lower, middle and upper) and two management conditions (with and without fungicide application). To the variable area under the disease progress curve, the lowest values were observed in the upper third of the TMG42WS and TMG43WS cultivars, with the lower and middle thirds presenting the highest severity. The condition managed with fungicide and the upper third showed the lowest values for area under the disease progress curve. The leaf area was negatively affected by the ramularia leaf spot. Concerning the seed and fiber yields, the highest averages were observed for the middle third and the condition managed with fungicide. There was no statistical difference for cotton yield loss.

Survey conducted during kharif2012–13 in ten villages of Guntur district revealed the highest incidence of Alternaria leaf spot (30%) followed by Cercospora leaf spot (12%), Tobacco Streak Virus disease (9%) and bacterial blight (5%) in Lam village. Grey mildew and rust diseases were not recorded at flowering stage. Intensity of Alternaria leaf spot, bacterial blight, grey mildew, Cercospora leaf spot and rust was to the tune of 12%, 3.0%, 6.6%, 6.0% and 8.2% respectively. The species associated with Alternaria leaf spot was identified as Alternaria alternata based on conidial characters. Among twenty popular varieties and hybrids evaluated at Regional Agricultural Research Station, Lam, Tulasi 144 BGII and U5-SS-33 BGII showed resistant reaction while Jadoo and Brahma recorded moderately resistant reaction against Alternaria leaf spot; eleven varieties viz., L 799, L 788, L 761, L 755, L 804, L 1011, L 1008, L 604, L 801, L 763 and L 808 were moderately resistant. Two hybrids KSPL (KDCCH-065) and NCS 9605 and three varieties viz., L 765, L 389, L 762 were moderately susceptible. One hybrid (SWCH 4746 BG II) and one variety i.e. Narasimha (NA1325) recorded susceptible reaction to Alternaria leaf spot. In conclusion cotton farmers, may choose disease resistant hybrids as a component of integrated disease management to reduce cost of plant protection and thus reap maximum benefits.

BACKGROUND: Plant production is severely affected by biotic and abiotic stresses R‐genes exhibit resistance against a range of diseases and pathogens in plants. The nucleotide binding site and leucine rich repeat (NBS‐LRR) class of R‐genes is the most comprehensively studied in terms of sequence evolution and genome distribution. The differential response for resistance against biotic and abiotic stress has been observed in cultivated and wild relatives of the genus Gossypium. RESULTS: Efforts have been made to address the recent evolution of NBS‐LRR sequences within Gossypium hirsutum and resistance gene analogue (RGA) sequences derived from G. arboreum and G. raimondii. The % identity and phylogenetic analysis of NBS‐LRR‐encoded RGAs from tetraploid New World cotton and its diploid ancestors G. raimondii and G. arboreum suggest that the evolution of NBS‐LRR‐encoding sequences in G. hirsutum occurred by gradual accumulation of mutants that led to positive selection and a slow rate of divergence within distinct R‐gene families. CONCLUSION: The allotetraploid genome of cotton, after separating from its diploid parents, experienced polyploidisation, natural and artificial selection, hybrid necrosis, duplication and recombination which became the reason to shed off and evolve new genes for its survival. These driving forces influenced the development of genomic architecture that make it susceptible to diseases and pathogens as compared to donor parents. © 2015 Society of Chemical Industry