Wild relatives of sorghum as sources of resistance to sorghum shoot fly, Atherigona soccata

The levels of resistance to shoot fly, Atherigona soccata in sorghum germplasm are low to moderate and therefore, we evaluated 17 wild relatives of sorghum under field and greenhouse conditions as an alternate source of genes for resistance to this pest. Thirty-two accessions belonging to Parasorghum, Stiposorghum and Heterosorghum did not suffer any shoot fly damage under multi-choice conditions in the field, while one accession each of Heterosorghum (Sorghum laxiflorum) and Chaetosorghum (S. macrospermum) suffered very low shoot fly damage. Accessions belonging to S. exstans (TRC 243601), S. stipoideum (TRC 243399) and S. matarankense (TRC 243576) showed absolute non-preference for oviposition under no-choice conditions. Accessions belonging to Heterosorghum, Parasorghum and Stiposorghum were preferred for oviposition, but suffered low deadheart formation. Manual infestation of seedlings with shoot fly eggs did not result in deadheart formation in some of the accessions belonging to S. exstans (TRC 243601), S. stipoideum (TRC 243399), S. matarankense (TRC 243576) and S. purpureosericeum (IS 18944). Larval mortality was recorded in main stems of the Parasorghums. Within section Sorghum, accessions belonging to S. bicolor ssp. verticilliflorum were highly susceptible to shoot fly, as were those of S. halepense. However, a few accessions such as IS 18226 (race arundinaceum) and IS 14212 (S. halepense) resulted in reduced survival and fecundity. Wild relatives of sorghum exhibited very high levels of antibiosis to A. soccata, while only low levels of antibiosis have been observed in the cultivated germplasm. Therefore, wild relatives with different mechanisms of resistance can be used as a source of alternate genes to increase the levels and diversify the basis of resistance to shoot fly, A. soccata

Seed microflora of five ICRISAT mandate crops

International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) supplies seeds of sorghum, pearl millet, pigeonpea, chickpea, and groundnut for research globally. The export of seeds of these crops is channelized through the regional station of the National Bureau of Plant Genetic Resources (NBPGR), Rajendranagar, Hyderabad. However, the tests for quarantine clearance of seeds for export are done at the Export Certification Laboratory at the ICRISAT Center. During the period from June 1989 to December 1997, ICRISAT exported 371,818 samples of its mandate crops to 136 countries. The largest number of exported samples were of sorghum (140,143) followed by chickpea (119,308). A total of 1786 samples (sorghum, 571; pearl millet, 120; pigeonpea, 311; chickpea, 199; Groundnut, 585) were detained due to heavy seed infection by fungi and/or bacteria (>80% seed infection). Pigeonpea appeared to be the most popular crop exported to 105 countries followed by sorghum (91 countries) and groundnut (88 countries). A total of 182 fungal spp. belonging to 71 genera were recorded. Largest number of fungi-132 fungal species across the years, were found associated with sorghum crop. The corresponding figures for pearl millet, chickpea, pigeonpea, and groundnut were 94, 91, 96, and 60, respectively. Aspergillus spp. were more on pulses and groundnut than on sorghum and pearl millet; however, Curvularia spp. showed the reverse trend. Fusarium and Alternaria spp. occurred most frequently on pigeonpea followed by on sorghum. Also, there was a total absence of three graminicolous fungi - Dreschlera, Biopolaris and Exserohilum spp. on groundnut. There were 31 fungi associated with all the five crops. Aspergillus niger (3.8%) and Cladosporium spp. (3.6%) were the most commonly occurring fungi being most predominant on groundnut and sorghum, respectively

Detection, seedborne nature, disease transmission and eradication of seedborne infection by rhizoctonia bataticola (Taub) butler in groundnut

A study was conducted to determine the seedborne nature, disease transmission and eradication of seedborne infection by Rhizoctonia bataticola in groundnut. In case of 10 groundnut accessions, infection percentage of R. bataticola, ranged between 13.3 to 73.3. Component-plating method indicated that the pathogen is located mainly on the seed coat and rarely in the endosperm and embryo. Infection in embryo and endosperm was always associated with seed coal infection. All accessions showed pre-emergence damping-off in the form of seed rot. Post- emergence damping-off was noticed in three accessions. The per cent infection ranged between 9.5 to 42.9 in case of pre-emergence damping-off. while it was 4.8 to 19.1 for post-emergence damping-off. The latent infection of R. bataticola from healthy seedlings was proved using Potato carrot agar medium. Infected seeds of 10 groundnut accessions were gi~own and no apparent symptoms were observed on the plants for one season, but seeds harvested from such plants resulted in seed infection of 6.1 - 33.3 % indicating the seed transmission nature of the pathogen from one generation to the next. Carbendazim + tin ram @ 2g a.i / kg seed can be used as a routine treatment in quarantine laboratories to eliminate R. bataticola from groundnut seed

Non-systemic Infection of Tobacco streak virus on Cotton in Warangal District, Andhra Pradesh

During 2005, cotton was sown on 3.67 lakh acres in Warangal district of Andhra Pradesh, 62 per cent of it being Bt seeds. Hybrid RCH - 2 Bt alone was sown on 1.20 lakh acres. During late August 2005, several farmers complained about a disease causing chlorotic/necrotic lesions on leaves accompanied occasionally with leaf purpling, necrotic buds and drying up of young bolls in their cotton fields. It was also noticed that the incidence of the disease was more on Bt cultivars, compared to non Bt cultivars. A survey was conducted in some of the cotton fields to ascertain the extent of incidence and also to collect disease samples for the identification of causal agent. Samples collected during the survey were tested by Enzyme linked immuno-sorbent assay (ELIS A) and studies carried out subsequently with cotton Tobacco streak virus (TSV) isolate gave interesting results, which we report hereunder

Not Available

Not AvailableThe National Bureau of Plant Genetic Resources Regional Station, Hyderabad has facilitated safe introduction of 356 521 (1986-2010) germplasm accessions of various crops into India. About 60 seed-borne pathogens of quarantine importance were intercepted on crop germplasm during seed examination in the laboratory and post-entry quarantine observations in the field. Of these, the quarantine pathogens, viz. Ralstonia solanacearum and peanut stripe virus in groundnut (Arachis hypogaea L.), Peronospora manshurica (Naum.) Syd. and peanut stripe virus in soybean [Glycine max (L.) Merr.], tobacco streak virus in sunflower (Helianthus annuus L.), Xanthomonas campestris pv holcicola (Elliot) Dye, Burkholderia andropogonis (Smith) Gillis et al. on sorghum [Sorghum bicolor (L.) Moench], Drechslera maydis (Nisik.) Subram. & Jain on maize (Zea mays L.) and Pseudomonas syringae pv tomato (Okabe) Young et al. on tomato (Lycopersicon esculentum Mill.) were intercepted from different countries. Yield losses that could have occurred were estimated had these pathogens of groundnut, soybean, sunflower, maize, sorghum and tomato not been intercepted.Not Availabl