RESEARCH PROJECTS  //  Research Report 2019/2020

New Research Projects

Investigation of the aggressive, seedborne nematode species Robustodorus arachidis N. Comb. on groundnut

Dr S Steenkamp
ARC Grain Crops Institute, Potchefstroom

Robustodorus arachidis (new combination) was originally identified as Aphelenchoides arachidis (testa nematode) on severely damage groundnut from the Vaalharts Irrigation Scheme, Northern Cape Province. It appeared as if this nematode was seed-borne, similar to Ditylenchus africanus (pod nematode). However, based on field observations, R. arachidis appeared to be more aggressive than D. africanus. Since R. arachidis was previously unknown and only identified in South Africa for the first time, there is no information available on this nematode. A lack of information on R. arachidis will hamper the implementation of effective and sustainable management strategies and enable this pest to spread unhindered. Therefore, the objectives of this part of the study were

  • to determine whether nematicides currently registered for control of plant-parasitic nematodes are effective in keeping this nematode under control,
  • to study the occurrence of R. arachidis on groundnut and compare it to D. africanus and
  • to determine whether crops planted in rotation with groundnut serve as host for R. arachidis.

To achieve these objectives, trials were planted by hand on the field in which this nematode was first discovered. The groundnut cultivar Sellie Plus was used in all of the trials. The trial involved in the evaluation of currently registered nematicides for the control of R. arachidis on groundnut consisted of a randomized complete block design with five treatments (including an untreated control) and six replicates. Nematode data was ln(x+1) transformed to lessen the natural variation within replicates and subjected to ANOVA. Means were separated, using the P < 0.05 Tukey test. The second trial in which the occurrence of R. arachidis was studied and compared to that of D. africanus, was planted in the same field. Nematode evaluations for both trials were done at harvesting. To achieve the third objective, groundnut, wheat and maize samples were collected throughout the year on the naturally infested site. All plant-parasitic nematodes were identified in soil, root and pod (in the case of groundnut) samples. R. arachidis occurred in soil, root and pod (hull and kernel) samples. None of the nematicides were able to keep the R. arachidis numbers significantly lower than that in the untreated control and was, therefore, not effective in the control of this nematode on groundnut during the 2019/2020 summer growing season. Compared to D. africanus, R. arachidis dominated in the pods although D. africanus numbers were higher in the root samples. It seemed as if these two nematode species competed for the same niche in the groundnut plant and that R. arachidis were more aggressive than D. africanus. Similar to the distribution of D. africanus within the groundnut plant, the highest portion of the R. arachidis population occurred within the pod. These trials confirmed, furthermore, that R. arachidis is seed-borne and are consequently likely to spread throughout the groundnut production area by planting of infested seed. In terms of host range, R. arachidis was not found on wheat during the winter season but it was not clear whether wheat is a non-host to R. arachidis or whether this nematode were inactive and survived in an anhydrobiotic resting phase or as eggs in the soil and plant rests present from the previous summer growing season. In the summer growing season high R. arachidis numbers were observed in maize root samples, indicating that maize is a definite host to this nematode. The effect of R. arachidis on maize yield is as yet unknown.

Sudden death syndrome of soybean in South Africa: etiology detection and management

Dr S Lamprecht

Sudden death syndrome (SDS) of soybean is one of the most important soilborne diseases of soybean and is responsible for economically devastating reductions in yields in North and South America. Several Fusarium species including Fusarium brasiliense, F. crassistipitatum, F. tucumaniae, and F. virguliforme cause the disease in other countries. Recent taxonomic changes in the genus Fusarium have resulted in all these species being synonymised under the current name Neocosmospora phaseoli. SDS was first reported in South Africa in 2013 in the Lydenburg/Badfontein area, Mpumalanga Province, on a no-till commercial farm planted to soybean cultivar PAN 737 under irrigation for a second consecutive season. The causal organism was initially reported to be F. virguliforme, but later re-identified as F. brasiliense and a novel Fusarium sp. Although F. brasiliense is currently included in N. phaseoli, the new Fusarium sp. reported in South Africa still needs to be identified. Judging by published information on the disease in other countries, SDS may pose a threat to the South African soybean industry. In order to conduct any epidemiological research and develop management strategies for SDS in South Africa, it is therefore essential to accurately identify the new Fusarium sp., and to determine the distribution and identity of all SDS causing Neocosmospora spp. (Fusarium spp.) in soybean producing areas in South Africa. The aim of the current study is not only to determine the distribution of the disease and the causal organisms, but also to develop a molecular technique for rapid identification of the SDS causing pathogen/s and for detection and quantification of these pathogens in soils and plant material and to develop management strategies. The first phase of the project include the collection of isolates of Neocosmospora spp. associated with plants displaying SDS symptoms, evaluating pathogenicity and virulence of the isolates and development of molecular tools for rapid detection and quantification of the pathogen in plant material and soil. Currently three gene areas of 90 isolates have been sequenced for identification and to determine the suitability of these for species-specific primer development. DNA of all the SDS causing species not previously reported in South Africa were also obtained from an international collection to include later in the primer testing and validation. The most effective technique and inoculum concentration to screen isolates for pathogenicity and virulence was identified by evaluating four inoculation techniques, using three SDS causing isolates. This technique will be used to screen all the isolates that will be included in the study. Unfortunately the first phase of the project had to be extended because of delays in the research and cancellation of surveys (to collect more isolates of SDS causing Neocosmospora spp.) caused by the Covid-19 lockdown. The remaining results for the first year of the project will only be available in March 2021.

An analysis of the Market for Soya

Prof F Meyer


Soybeans and its related products are used in a multitude of forms in different food products. Defatted soybeans specifically can be processed into four main derivative products, namely, white flakes, textured vegetable protein (TVP), soy concentrates and soy isolates. Textured vegetable protein is typically used as meat analogues or extenders, whereas concentrates (90% protein with sugars removed) and isolates (90%+ protein with sugar and fibre removed) are normally used to enhance the protein levels in products such as breakfast's cereals. Isolates are also common in processed meat and other food products that require an additive with water absorption qualities.

Based on exploratory discussions with industry stakeholders it appears that TVP, and to a lesser extent white flakes, are the only defatted soy derivatives that are produced in South Africa. In the case of TVP, Philafrica Foods dominates the market by producing roughly 90% of total TVP production in South Africa. Other products such as isolates and concentrates are imported into South Africa.

Full fat soy is also used for human consumption. Although this is conventionally included as a protein source in a fortified maize soy blend in feeding schemes, uses for full-fat soy, as a component of processed products for human consumption, seems to be increasing. A good example of a recent innovation is Soybean Butter that is a spread similar in taste and texture to peanut butter sold in Woolworths. It is flavoured and produced in small batches and provides an alternative to peanut butter.

Research Objective

The overarching objective of the proposed project is to gain a comprehensive understanding of the market for soy-derived products in South Africa. In order to achieve this, the diverse nature of soy-derived products, for human consumption should be taken into account (the recent project for the Oilseed Advisory Committee as prepared by the University of Pretoria can be used as a point of departure here.)

Based on this, three distinctive product groupings will be considered in this project.

The first is white flakes and TVP. Since these are currently produced in South Africa, a comprehensive analysis of the local market is required. In terms of TVP, it is also important to consider the dichotomy associated with it. On the one hand, it serves as a meat substitute for low(er) income consumers and on the other, it provides a niche market as a meat analogue for health conscious / vegetarian consumers. Based on this the following issues relating to TVP will be investigated:

  • The current size of the South African TVP market and key stakeholders.
  • Current product mix and flow associated with TVP i.e. what proportion is used for low-cost meat substitutes and extenders and what proportion is used for high-cost meat analogues and health products.
  • Low-income consumers' perceptions around TVP as a meat substitute/extender.
  • High-income consumers' perceptions around TVP as a meat substitute/extender.
  • Growth potential of TVP market based on consumer perceptions and recent consumption trends.

The second category to be investigated is the imported products, which comprise of concentrates and isolates. These products also have numerous uses and are often included and marketed as 'smart protein' included in cereals, breakfast food and fitness products. Although isolates are also included, as mentioned above, as an absorption agent, high(er) income and health-conscious consumers are progressively considering soy as a protein supplement. Soy protein has also been proven to reduce the risk of Cardiovascular Disease and reduced risk of breast cancer due to isoflavones which have estrogen-like effects. It is, however, unknown to what extent high(er) income consumers in South Africa are aware of these health-claims and if they are unaware, to what extent they will respond (purchase) if the positive attributes of these products are marketed more aggressively. In this regard the specific research issues related to soy concentrates and isolates will be investigated:

  • The current levels of isolate and concentrate imports.
  • The current uses and product flow associated with these derivative products, i.e. what proportion is used as absorption agents and what proportion is used for products with specific health-related claims.
  • High(er) income consumers' level of knowledge regarding soy-based proteins and their associated health claims and their perceptions related to this.

High(er) income consumers' level of knowledge regarding soy-based proteinsand their associated health claims and their perceptions related to this.

  • The volume of full-fat soy, currently being used in for human consumption.
  • Consumers' knowledge and perceptions on full-fat soy products and willingness to pay for products containing full fat soyas. Here the Oilseeds Advisory Committee mentioned an extruded type of product where soybeans are extruded and mixed with maize meal. The willingness to pay/accept such a product can also be gauged.

Research Approach

It is proposed that this research is conducted in two phases:

Phase 1: Product flow and value chain mapping

The first phase will entail a value chain analysis of 5 soy derivative products namely:

  • White flakes
  • TVP
  • Concentrates
  • Isolates
  • Full-fat soya products

The value chain analysis will include a mapping exercise in which the flow of products, through the various nodes are depicted from producer to final consumer. Each of the respective nodes will then be discussed systematically. The flow and associated discussions will show the volumes of production, consumption and trade associated with the various products and key cost drivers and output prices. A potential limiting factor in phase 1 could be the reluctance of industry role-players to share information relevant to the project. Here collaboration and official endorsement of the Oilseeds Advisory Committee could be advantageous.

Phase 2: Consumer knowledge, perceptions and room for consumption growth in two of products covered in the value chain analysis

The objective of this phase is to gauge consumer's knowledge and perceptions regarding selected soy products. This knowledge can serve as a point of departure for projecting growth in demand for the products under consideration. This phase could also include the testing of consumers' reaction to favourable price and health claims associated with soy products in order to inform future marketing initiatives.

In order to gather information on perceptions and knowledge levels the collection of primary data is required. Within this context this phase will consist of questionnaire development, and recruitment of consumers as respondents in the survey. Based on information obtained through the surveys, selected experimental auctions can be developed and hosted to validate that the information from the surveys does correspond to the (economic) choices that consumers make.

An Experimental auction is a marketing tool used to elicit consumers' willingness to pay a premium or discount for a certain product, compared to a product with a differentiated attribute such as an alternative brand or quality (here meat and meat analogues can be considered an example). Various variants of such auctions exist and are commonly applied in agricultural and food marketing studies since they are deemed to be demand revealing. It is proposed that the specifics of such an auction be determined after the value chain analysis, however, based on initial knowledge there are two options that should be explored to inform marketing and investment decisions into derivative soy product manufacturing for human consumption:

  • Consumers' willingness to accept meat analogues such as Toppers. This scenario could specifically explore what the nature of relative prices should be for consumers (with different characteristics) to move from meat to meat analogues.
  • Consumers' willingness to pay for 'Smart protein' claims associated with soy protein. This could explore the notion that if this claim is marketed aggressively it would induce growth in the consumption of these products. This could relate to products that include these proteins in the form of isolates or full fat soyas.

Data Collection

In terms of Phase 1 data will be collected from secondary sources (such as SARS customs data for trade figures) and through discussions with industry experts where no official statistics are available. Phase 2 will comprise of a consumer survey and associated auction for which the specifics will be determined through discussions with the Oilseeds Advisory Committee.