Methodology for Screening Sorghum Resistance to Storage Pests

To arsist plant breedrrs in obtaining suitable material for screening sorghum resistance ro storage insect attack, test grain from a suscepribb varierr [Red S-I) w a c wed rok'erermlnt the berr com~trnttoncf m t n i d :rial mateni h h ~ p t i wiln ltrmt~oT~n nrrr masrrr o{ IC I! ard2O n Lrre ~nlrrtrrlv lth 10. I.' i0,25, 30, 35, and 40 10.day.oldhult we1,iL ( ~ ~ t i ~ h tol&uose ] anddth the same quantines of eggr of rhe grain moth [Sitotroga cerealella). Results are discussed according to progeny output in relation to infestation leusL and grain mnrs Combi~tlonso f30 waevilr and 20 g ofgrain, and 40grain moth eggs and 15 g ofgrain are ncommendedfor use in funher resirlance screenin

A review of laboratory and field screening procedures for Chilo partellus

Laboratory and field methodologies for screening for resistance against Chilo partellus on sorghum and maize are reviewed in relation to the insect biology, plant phenology and insect-plant interaction. The value of field and laboratory techniques in achieving the goal to produce resistance varieties and hybrids is discussed. Recommendations for future work are mad

Drought-Tolerant Crops for Southern Africa Proceedings of the SADC/ICRISAT Regional Sorghum and Pearl Millet Workshop, 25 - 29 Jul 1994, Gaborone, Botswana

Small-scale farmers in southern Africa have traditionally relied on sorghum and millet to feed their families. Seventy-five delegates from 17 countries participated in the SADC/ICRISAT Regional Sorghum and Pearl M i l l e t Workshop held at Gaborone, Botswana, 25-29 Jul 1994, to discuss ways of improving sustainable food production in semi-arid areas. Recent research on sorghum and pearl millet was reviewed through presentations that discussed the role of three broad disciplines—genetic enhancement, crop protection, and technology transfer—in increasing food security at household level. Priority areas include enhancement of seed production, strategies of crop protection, reliable on-farm trials to identify promising varieties, and more effective technology transfer

Chemical control of sorghum head bugs (Hemiptera: Miridae)

Eight contact and three systemic insecticides, and an enriched neem extract were tested for the control of sorghum head bug, Calocoris angustatus Leth. at the ICRISAT Center. The insecticides were applied at the complete-anthesis and milk stages (at 500 1/ha) with a knapsack sprayer. On the basis of effectiveness of head bug control, grain yield and 1000-grain mass, carbaryl (at 500 g a.i./ha) was the most effective insecticide followed by fenvalerate (at 50 g a.i./ha), and chlorpyrifos (at 250 g a.i./ha). Among the systemic insecticides, demeton-S-methyl (at 250g a.i./ha), was the most effective. Demeton-S-methyl and dimethoate were also effective for the control of other head bug species—Eurystylus bellevoyei Put. and Reut. and Campylomma sp. Plots sprayed with demeton-S-methyl gave higher grain yields than those treated with carbaryl, which was the best contact insecticide. Two sprays of carbaryl (at 500g a.i./ha) applied at the complete-anthesis and milk stages have been found to be effective for head bug control. Dichlorvos, fenitrothion and monocrotophos were highly phytotoxic and resulted in burning and drying of entire leaves. Dimethoate resulted in a slight drying of leaf tips and margins

Potential Use of Benomyl for Control of Ergot (Claviceps africana) in Sorghum A-lines in Zimbabwe

In the absence of a successful practice for the control of ergot (caused by C. africana) on sorghum A-lines (male-steriles) in Zimbabwe, 2 fungicides, benomyl as Benlate and thiram, were tested in greenhouse and field experiments conducted at the Matopos and Henderson Research Stations, Zimbabwe in 1993. Fungicides were either applied to sorghum panicles singly, at concentrations of 0.1 or 0.2% a.i., or combined in mixtures at 0.1% a.i. each. Fungicides were applied before inoculation at heading or stigma exsertion or after disease became visible. Treatment with either benomyl or thiram was ineffective if applied when disease first became visible. A significant reduction in initial disease severity, rate of disease increase and final disease severity was achieved with 1 application of benomyl at 0.2% a.i. at heading or stigma exsertion. At the concentrations tested benomyl and thiram did not reduce seed-set in R- (restorer) lines

Factors influencing oviposition behaviour of the sorghum midge, Contarinia sorghicola Coq.

Visual stimuli influence the orientation behaviour of the sorghum midge, Contarinia sorghicola Coq. (Diptera: Cecidomyiidae). Yellow, red and white colours are attractive to the midge while blue and black are least attractive. Sorghum panicles covered with blue- or black-coloured bags in a headcage showed maximum midge damage, while the reverse was true for panicles covered with yellow, red, and white coloured bags. Panicles at half-anthesis with viable pollen and receptive stigmata suffered higher damage than those at the pre- and post-anthesis. Physical removal of anthers and stigmata significantly reduced the oviposition by the sorghum midge. Reduced oviposition/adult emergence was also recorded in male sterile sorghum lines (2219A and 296A) or through chemically- (Ethrel) (2-Chloro ethyl-phosphonic acid) induced male sterility in panicles of the sorghum cultivar, Swarna. Chemical stimuli from viable pollen and receptive stigmata and to a limited extent physical stimuli, govern the oviposition behaviour of the sorghum midge. Sorghum cultivars IS 12573C, S-GIRL-MR1 and IS 2816C showed antixenosis to adult midges. However, these cultivars became susceptible under no-choice conditions in the headcage. DJ 6514 and IS 12666C were attractive to the adult midges, but showed antixenosis to oviposition under natural and no-choice conditions. Genotypes with short florets showed antixenosis for oviposition. Ovary and anther breadth and tannin content of grain showed negative associations with oviposition. Cultivar antixenosis to adult midges and oviposition is an important component of resistance to the sorghum midg