ARC Grain Crops Institute

Potchefstroom, South Africa

ARC Grain Crops Institute

Potchefstroom, South Africa
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News Article | April 21, 2016

HIV-positive farmer Eunice Chiyabi walks near a field of maize during a visit by a home-based care team in Chikonga village, close to the town of Chikuni in the south of Zambia February 21, 2015. REUTERS/Darrin Zammit Lupi PRETORIA (Reuters) - South Africa's estimates for key crops such as maize have become increasingly accurate thanks to satellite imagery and as farmers' often biased input has been cut out of the picture, a conference was told on Thursday. South Africa's maize crop has been hard hit this season by a scorching drought, bringing into sharp focus the need for accurate forecasts of the harvest's size to guide government policy and markets. From 1997 to 2002, all of the maize forecasts made by the official Crop Estimates Committee (CEC) underestimated the size of the harvest, said Eugene du Preez, director of privately-held SiQ, which provides the committee with satellite and aerial data, which helps it determine the size of the area planted. "That was a red flag," Du Preez said. The reasons for the underestimates were clear -- the CEC was relying on farmers for much of its information, and they had a transparent incentive to say they had planted less than they had because that would support prices. Du Preez said from 2003 until 2008, five of the six forecasts underrated the size of the crop. "We started providing the government with data in 2002, and at that stage we were still very much providing them with information coming from farmers, and there was problems with that," Du Preez told Reuters on the sidelines of a conference on monitoring food insecurity threats from space. "And then we decided we needed to change the system. So we developed the producer independent crop estimate system." The system includes satellite images and also surveys conducted with the use of low-flying aircraft. For yield estimates, the CEC relies in large part on on-site surveys conducted by the state-run ARC Grain Crops Institute. "They are doing work in the three main maize provinces, Mpumalanga, Free State and North West," said Marda Scheepers, a senior statistician with the CEC. "They go into a field and they do crop counts and plant counts to get an average yield for the province," she said. From 2009 to 2015, the CEC had three underestimates and four overestimates for the size of the crop. And it has been getting closer to the actual crop size. Du Preez said from 1997 to 2002, its forecasts were routinely 6 or 7 percent off target and even close to 13 percent out. But he said the average since 2009 was 2.6 percent and last year the difference between the CEC's final forecast and the size of the harvest was 0.2 percent. South Africa will likely harvest 7.1 million tonnes of maize in 2016, 29 percent less than the 9.95 million tonnes reaped last year because of drought and late plantings, the CEC said last month. Its next forecast is due next week and a Reuters poll sees it cutting its last estimate by 5.5 percent to 6.7 million tonnes. [L5N17M27X]

Kruger M.,North West University South Africa | Rensburg J.R.J.V.,ARC Grain Crops Institute | Berg J.V.D.,North West University South Africa
Environmental Entomology | Year: 2011

The first report of resistance of the maize stem borer [Busseola fusca (Fuller)] to Bt maize (MON810) was made in the Christiana area of South Africa during 2007. The objective of this study was to evaluate the status of resistance of other populations of B. fusca to Bt maize. One greenhouse and two laboratory studies were conducted. B. fusca populations were collected on Bt maize as well as the adjacent refugia (conventional maize and non-Bt maize) in the Vaalharts area, 50 km from the Christiana site. Control populations were collected from sites where Bt maize was not planted. In the greenhouse study 720 potted plants were each artificially infested with 10 neonate larvae of the F1-generation after the field collected populations were reared through to adults. Numbers of live larvae and larval mass per plant were determined at regular intervals over a 35-d period. Larvae of the Christiana conventional population (Bt-susceptible) on Bt maize (CHR08ConBt) and Bethal conventional population (Bt-susceptible) on Bt maize (BET08Con-Bt) did not survive on Bt maize for longer than 12 d. The populations collected from both Bt (VAA08Bt-Bt) maize and refuges (VAA08Ref-Bt) at Vaalharts were resistant and the subsequent generation of larvae completed their life cycle on Bt maize. Similar results were observed in the laboratory experiments. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810). The geographical distribution of resistance was shown to include at least the Vaalharts area, in addition to the original report for the Christiana area. These observations that larvae collected from refugia at Vaalharts was resistant, show that the efficacy of the refuge strategy is compromised in this area because the contribution of refugia did not produce large enough numbers of susceptible individuals to mate with moths of which larvae survived inside Bt maize fields. © 2011 Entomological Society of America.

Kruger M.,North West University South Africa | Van Rensburg J.B.J.,ARC Grain Crops Institute | Van den Berg J.,North West University South Africa
Crop Protection | Year: 2014

A concern regarding planting of Bt crops is that their widespread cultivation could lead to evolution of insect resistance to Bt toxins. In South Africa, the noctuid maize stem borer (Busseola fusca [Fuller]), is resistant to Bt maize (Zea mays L.; MON810) which produces Cry1Ab protein. The presence of fitness costs in resistant populations could be a valuable component of resistance management since the non-Bt maize refuge may select against resistance. The aim of the study was to determine if there are fitness costs associated with Bt resistance of B. fusca. Life history parameters were compared between individuals of a Bt maize resistant B.fusca population when feeding on Bt or non-Bt maize. Similar comparisons were done using a control population. Field collected larvae as well as their F1-generation were used in the study. The following parameters were compared: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. Except for LT50-values, no fitness costs were associated with the resistance trait in the highly resistant B.fusca population. The absence of fitness costs and presence of resistant populations may promote the use of a multi-gene strategy which would be expected to impact negatively on fitness. © 2013 Elsevier Ltd.

Kruger M.,North West University South Africa | Van Rensburg J.B.J.,ARC Grain Crops Institute | Van Den Berg J.,North West University South Africa
African Entomology | Year: 2012

The maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), is of economic importance throughout sub-Saharan Africa. The seasonal activity pattern of this pest is characterized by two to three distinct generations during spring and summer followed by a diapause period of approximately six months during autumn and winter. Genetically modified Bt maize (MON810) that expresses an insecticidal Cry1Ab protein has been deployed in South Africa since 1998 to manage stem borers. The first report of field resistance of B. fusca to Bt maize was made during the 2006 cropping season. Resistant strains of this pest are expected have reduced fitness compared to susceptible individuals. Information regarding fitness of resistant individuals that survive on Bt maize could contribute to the understanding of resistance evolution as well as to development of improved resistance management strategies. Life history parameters of different B. fusca populations were compared in a laboratory study using diapause (spring) as well as second-generation (summer) populations. Sex ratio, pupal mass, fecundity and longevity of moths of field-collected Bt-resistant and susceptible B. fusca populations were compared. Slight adverse effects of Bt maize on fitness of the resistant summer-population were observed. The sex ratio was biased towards males in some resistant populations and towards females in susceptible populations. The resistant population had a lower mean pupal mass, shorter longevity of moths and reduced fecundity.

Kruger M.,North West University South Africa | Van Rensburg J.B.J.,ARC Grain Crops Institute | Van den Berg J.,North West University South Africa
Journal of Applied Entomology | Year: 2012

Based on surface area, South Africa is currently ranked the eighth in planting genetically modified (GM) crops in the world. Bt maize (MON810) has been grown to control lepidopterous stem borers in South Africa since its first release during 1998. The first report of resistance of the African maize stem borer, Busseola fusca (Lepidoptera: Noctuidae) and poor compliance to refuge requirements that could have contributed to resistance development prompted this study which was done in the main maize production area of South Africa. Objectives were to evaluate farmer's perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how it was applied between 1998 and 2010. This study involved 105 commercial farmers covering 87778ha of maize throughout the main maize production region on the Highveld of South Africa. A questionnaire survey was conducted and addressed signing of technical agreements upon purchasing GM seed, refuge compliance, pest management practices, perceived benefits and risks relating to Bt maize. Compliance with refugia requirements was low especially during the initial 5-7years after release. An alarmingly high number of farmers applied insecticides as preventative sprays on Bt maize and refugia irrespective of stem borer infestation levels. A large proportion of farmers reported significant borer infestation levels on Bt maize and between 5% and 93% farmers in all districts applied insecticides to Bt maize to limit borer damage, indicating that the occurrence of resistance is more wide-spread in the country than previously thought. This study shows irresponsible management of GM crop technology by farmers, chemical and seed companies. Concerns and perceptions of farmers in South Africa seem to differ from those in Europe. South African farmers perceived little, if any, negative impact on non-target organisms and remain positive about the technology in spite of resistance development. Other studies indicated that European farmers were concerned about these aspects. A shared concern, however, was consumer acceptance of GM maize and marketability on the export market. © 2011 Blackwell Verlag, GmbH.

du Plessis H.,North West University South Africa | du Plessis H.,ARC Grain Crops Institute | Byrne M.J.,University of Witwatersrand | van den Berg J.,North West University South Africa
Entomologia Experimentalis et Applicata | Year: 2012

Nysius natalensis Evans (Hemiptera: Orsillidae) is a pest of sunflower in South Africa. Adults invade sunflower fields from their weedy hosts which occur inside crop fields and on surrounding headlands. The host plant suitability for survival and reproduction as well as the effect of within-generation host switching was studied on different wild host plants and sunflower. Life history parameters used to assess host plant suitability were F 1 adult survival, pre-oviposition period, fecundity, and longevity. Nymphs and adults were provided with stems and seeds of five host plants, viz., Amaranthus hybridus L. (Amaranthaceae), Portulaca oleracea L. (Portulacaceae), Chenopodium album L. (Chenopodiaceae), Conyza albida Spreng. (Asteraceae), and sunflower, Helianthus annuus L. (Asteraceae). Nymphs were reared on crushed seed of the five plant species. After completion of the nymphal stage, emerging adults of each host plant group were provided with seed of a different host plant species for food. Adults did not survive long on stems only and very few eggs were laid. Seeds of the host plant species were shown to be an essential source of nutrients for N. natalensis reproduction, whereas the vegetative plant parts were unsuitable. Nymphal food and host-plant switching between the nymphal and adult stages significantly affected the pre-oviposition period. Nymphal and adult food source also affected female longevity. The number of eggs laid was not influenced by nymphal food, but was influenced by adult food and the switch between nymphal and adult food. The comparative attractiveness of sunflower and wild host plants for oviposition was also investigated and showed that females preferred to lay eggs on wild host plants, compared with sunflower. These results may explain why N. natalensis will lay their eggs on sunflower after weeds in the vicinity are controlled, or senesce toward the end of the growing season. © 2012 The Netherlands Entomological Society.

Chigeza G.,ICFR | Chigeza G.,University of KwaZulu - Natal | Mashingaidze K.,ARC Grain Crops Institute | Shanahan P.,University of KwaZulu - Natal
Field Crops Research | Year: 2012

Genetic improvement for seed yield and oil-content in sunflower cultivars was initiated in the early 1970s in South Africa. Since then no study has been carried out to assess the progress and contribution of new cultivars to seed yield improvement to justify continued investment into breeding new cultivars. The aim of this study was therefore to quantify the contribution of new cultivars to seed yield and associated traits in sunflower over four decades of breeding in South Africa. Two data-sets were used in this study: (1) side-by-side evaluation of historical and current sets of popular cultivars in the same environment under one set of trial management practices; and (2) yield trends in commercial farmers' fields based on annual production estimates. The absolute genetic gain (yield increase per year) for seed yield in the side-by-side trials ranged from 18 to 32kgha -1year -1 with a mean of 24kgha -1year -1. In contrast, the absolute seed yield increase under commercial production was 12kgha -1year -1. The estimated relative genetic gain for seed yield based on side-by-side trials was 1.5% year -1 and the relative gain in seed yield per year under commercial production was 1.9% year -1. The contribution of new cultivars to total seed yield progress in sunflower were 56.3% for the period 1970-1989; 23.9% from 1990 to 2009 and the mean over the four decades under consideration 1970-2009 was 41.6%. Positive increases in genetic gains for oil yield, oil content and number of seeds per head were also obtained although the gain in oil content was relatively low. © 2012 Elsevier B.V.

Chigeza G.,ARC Grain Crops Institute | Chigeza G.,University of KwaZulu - Natal | Mashingaidze K.,ARC Grain Crops Institute | Shanahan P.,University of KwaZulu - Natal
Euphytica | Year: 2013

As a plant breeding programme matures there is a general tendency to recycle elite inbred parents, a strategy known as advanced cycle pedigree breeding. The challenge with this approach is not only to maintain genetic variability in the base breeding populations but also their usefulness for further genetic advancement in developing experimental hybrids with better performance than the commercial hybrids on the market. To assess the genetic variability and usefulness of breeding populations in sunflower (Helianthus annuus L.), 109 new inbred lines across four breeding populations Pop1, Pop2, Pop3 and Pop4 in advanced cycle pedigree breeding scheme were testcrossed to two testers to form testcross hybrid (TCH) groups: Pop1TC, Pop2TC, Pop3TC and Pop4TC. Moderate to high genetic variability along with high heritability were obtained for seed yield and oil yield within and across all TCH groups. Heritability for oil content was low to high ranging from 0. 36 (Pop2TC) to 0. 81 (Pop1TC). Genetic advance (GA%) with a 10 % selection intensity ranged from 36 % (Pop2TC) to 42 % (Pop1TC) for seed yield; 38 % (Pop3TC) to 43 % (Pop1TC) for oil yield; and 1. 3 % (Pop2TC) to 5. 1 % (Pop1TC) for oil content. To quantify the commercial potential of experimental TCHs, founder parent heterosis (FPH), mid-standard heterosis (MSH) and high standard heterosis (HSH) were calculated. Out of a total of 218 experimental TCHs evaluated, 28 had positive FPH, MPH and HSH values for oil yield representing a 13 % selection intensity as is usually applied in early generation testing. © 2012 Springer Science+Business Media Dordrecht.

Chigeza G.,ARC Grain Crops Institute | Chigeza G.,University of KwaZulu - Natal | Mashingaidze K.,ARC Grain Crops Institute | Shanahan P.,University of KwaZulu - Natal
Euphytica | Year: 2014

Combining ability is one of the most important information breeders use to identify superior inbred lines on the basis of their performance in hybrid combinations. The objectives of our study were (i) to quantify the importance of general combining ability (GCA) and specific combining ability (SCA) variances for seed yield, oil content and oil yield; and (ii) estimate GCA and SCA effects of seed yield, oil content and oil yield of inbred lines developed from advanced cycle pedigree breeding populations in sunflower. A total of 109 female S3 cytoplasmic male sterile (CMS) lines from four bi-parental populations in advanced cycle pedigree breeding were crossed with two testers to form 218 testcross hybrids (TCHs). The TCHs were then evaluated in three environments. Variance component analysis results showed predominance of σ2gca over σ2sca for seed yield and oil yield indicating that superior TCHs can be identified based on positive and significant GCA effects of the female lines. For oil content σ2sca was predominant over σ2gca indicating that selecting for TCHs with high oil content would be best among line × tester combinations and not among female S3CMS lines per se. The proportion of GCA and SCA effects in the best five TCHs in each breeding population also confirmed the predominance of GCA effects over SCA effects for seed yield and oil yield while for oil content both GCA and SCA effects appear to be important, with SCA effects having more influence than GCA. The best selection strategy would therefore be to capture the GCA in the early stages of inbreeding and then SCA for the few unique combinations when lines are almost fixed. © 2013 Springer Science+Business Media Dordrecht.

Liebenberg M.M.,ARC Grain Crops Institute | Pretorius Z.A.,University of the Free State
Journal of Phytopathology | Year: 2011

The reaction of the first (1983) common bean international differential set and other germplasm to 248 single pustule isolates of the rust fungus Uromyces appendiculatus, collected from various southern African countries, was evaluated. Eleven of the most important isolates were re-purified and re-inoculated, this time also on the second (2002) revised and smaller international differential set. The 248 isolates could be grouped into 44 race-groups. These were subjected to principal coordinates analysis (PCoA). A second PCoA was carried out using 25 of the most important of the 44, together with 34 African races reported by previous authors. Isolates were generally avirulent on accessions with the resistance genes Ur-3+, -5 or -11, as well as Compuesto Negro Chimaltenango (CNC) and A 286, all small seeded, and the most useful sources were accessions carrying both Ur-3 and Ur-11, for instance BelMiNeb-RMR-7, BelDakMi-RMR-14 and -18. Isolates were generally virulent on large seeded accessions (with, among others Ur-4, -6 or -9), reflecting the preference for large seeded beans in southern Africa and co-evolution of host and pathogen. No large seeded accessions showed broad resistance. The least susceptible was Plant Introduction 260418, which rated resistant to moderately susceptible to the 11 races. These observations were confirmed by field ratings on the same accessions over multiple seasons. According to the PCoA, which proved useful for the identification of differentiating accessions, southern African isolates fell into three main clusters, for which Redlands Pioneer and the South Africa cultivar Teebus were the most discriminating differentials. Other accessions that showed particularly useful differentiating ability were Olathe and 51051. Of these, only Redlands Pioneer has been included in the 2002 differential set. The PCoA grouping of the African races was similar to that of the southern African race-groups. © 2010 Blackwell Verlag GmbH.

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