Joint Research Projects

1. Income and cost budgets of soybean and canola

   Mr SG Ferreira
   Agriconcept and Protein Research Foundation

   The 2015/16 research report included a complete description of the composition and functions of income and cost estimates. However, Mr SG Ferreira of Agriconcep indicated that he can no longer do the income and cost estimates due to increased work pressure. The PRF approached Grain SA and BFAP in an attempt to avoid duplication, but also to maintain the same format that all got used to over so many years. The next research report will contain more detailed information about the new approach and will highlight any changes that may become necessary.

   The PRF is very grateful toward Mr Ferreira for all the years of handling this very important project on behalf of the PRF.

2. Evaluation of PRF soybean elite lines under South African conditions

   Mr GP de Beer and Mr WF van Wyk
   Protein Research Foundation

   The PRF soybean elite trials (2016/17) were planted at the following six (6) localities:

   Stoffberg	Representing the Northern Highveld (cool area)
   University of Pretoria (Hatfield)	Representing the Southern Highveld (moderate to warm area)
   Brits	Representing the Northern irrigation area (warm area)
   Potchefstroom	Representing the Western production area (moderate to cool area)
   Bethlehem	Representing the Eastern and Northern Free State (cool area)
   Ukulinga (Pietermaritzburg)	Representing KwaZulu-Natal (warm area)

   The following four (4) local cultivars were used as standards for the trials:

   LS 6240 R	–   M.G 4.0
   DM 5953 RSF	–   M.G 5.0
   LS 6164 R	–   M.G 6.0
   NS 7211 R	–   M.G 7.0

   Seed institutions of South America (Argentina, Uruguay and Brazil) entered 58 elite soybean lines that were evaluated with the four (4) standards at the six (6) localities according to grain yield and general adaptation to South African conditions. The maturity groups (M.G) varied between M.G 4.0 to M.G. 7.4. The trial at Ukulinga was controlled preventively, using registered fungicides, against soybean rust.

   A number of the 58 lines produced relatively high grain yields of 5 716kg/ha, 5 702kg/ha and 5 084kg/ha. The best overall yield was produced in Pretoria (UP) by the control DM 5953 RSF at 6 335kg/ha.

   The project creates the opportunity for participating institutions to test their materials and to consider local registration of cultivars. As such it expands the choice of soybean cultivars in South Africa to the benefit of soybean producers and the soybean industry in general.

3. Management strategies for soilborne diseases of soybean in South Africa

   Dr YT Tewoldemedhin and Dr SC Lamprecht
   ARC – Research Institute for Plant Protection

   Seed treatment is a very important part of integrated management strategies against soilborne diseases of field crops. Surveys conducted in the major soybean production areas during 2010/11, 2011/12 and 2013/13 showed that many important soilborne pathogens are present in soybeans in South Africa. Many of these pathogens such as species within Fusarium, Pythium and Rhizoctonia affect seedling survival and establishment of soybean crops. In order to protect seedlings against these pathogens, glasshouse trials were conducted during 2014/15 and 2015/16 to evaluate fungicide seed treatments against damping-off and root rot caused by the most important soilborne pathogens. Three of the most effective treatments were selected for evaluation under field conditions. The current study therefore included the evaluation of the seed treatments Evergol (TR1), Celest XL+Apron XL (TR2), Maxim Quatro (TR3) and untreated seed (TR4) on three soybean cultivars viz DM 6.8i.RR, PAN 1454R and SSS 5052 in the cool (Bethlehem), moderate (Potchefstroom) and warm (Groblersdal) production areas. The field trials at Groblersdal and Potchefstroom were irrigated and the trial at Bethlehem was planted under dryland conditions. Soil was also collected from the trials to conduct similar tests under glasshouse conditions to evaluate the seed treatments on the three cultivars. The survival of seedlings at Bethlehem was significantly higher for treatments with Evergol and Celest XL+ Apron XL than for untreated seed. The same trend was recorded at Groblersdal and Potchefstroom although there were no significant differences in survival of seedlings from the different seed treatments at these localities. In non-pasteurised soil from Bethlehem under glasshouse conditions, all three treatments significantly improved survival of seedlings with TR1 and TR2 treatments resulting in the highest survival rates and in Groblersdal soil TR1 and TR2 also significantly improved survival, but in soil collected from Potchefstroom TR2 was significantly more effective than TR1 and TR3 to improve survival. Although the survival of seedlings was highest six weeks after planting at Bethlehem and Groblersdal for DM 6.8iRR and PAN 1454R, the yields were highest at Bethlehem and Potchefstroom. Unfortunately heavy rain and bird damage at Groblersdal resulted in very low yields in the field trial. It therefore appears that survival of seedlings is not always correlated with yield under field conditions and that other factors also affect yield. At Potchefstroom treatment of seed of cultivar DM 6.8iRR with Evergol (TR1) increased yield with 4.5% and treatment with Celest XL + Apron XL (TR2) increased yield with 17.8%. However, for cultivar PAN 1454R treatment TR1 increased grain yield with 34.5% and TR2 with 13.3%.

   Overall increases in yield of the two cultivars combined at Bethlehem showed an 18.4% increase for TR1 and 6.3% increase for TR3 at Bethlehem and a 16.6% increase for TR1 and a 16.0% increase for TR2 at Potchefstroom compared to the untreated seed treatment (TR4) control. Although these increases were not statistically significant, it is biologically significant and shows the huge impact that seed treatments can have on yield, but also that the same seed treatment can have a different effect on different cultivars. Survival of SSS 5052 seedlings was significantly lower than the survival of seedlings of the other two cultivars at all the localities and it was interesting to note that the yield of cultivar SSS 5052 at Potchefstroom was significantly higher for the untreated seed than seed treated with the three fungicides. This confirms the suspicion that this cultivar was unfortunatley double treated and that this caused the plots from the treated seed to have such a poor performance. Treatment of seed with Evergol (TR1) significantly reduced growth of seedlings under glasshouse conditions, especially on seedlings younger than two weeks old. However, despite the growth reduction in young seedlings, this seed treatment proved to be very effective in improving survival of seedlings and grain yield and also appears to be more effective for the control of Fusarium species that are pathogens of soybean seedlings than Celest XL + Apron XL. Soil pasteurisation and seed treatments TR1, TR2 and TR3 significantly reduced cotyledon and root rot severity for all three cultivars under glasshouse conditions. Treated seed plated to determine the effect of seed treatments on the incidence of seedborne fungi showed that, of the eight potential pathogens isolated from untreated seed, F. equiseti and P. longicolla could still be isolated from TR1 treated seed, B. maydis, F. equiseti, F. temperatum, F. verticillioides, Phomopsis sp. and P. longicolla from TR2 treated seed, and F. equiseti and P. longicolla from TR3 treated seed. Surface disinfestation eliminated many of the seedborne fungi, however, F. equiseti and P. longicolla could still be isolated from surface disinfested seed. It is also important to note that fungi that were seedborne such as F. verticillioides and P. longicolla were significantly more often isolated from seedlings planted in pasteurised compared to non-pasteurised soil which demonstrates the transmission of these pathogens from seed to seedlings. The glasshouse test conducted to determine the effect of potential pathogenic fungi isolated from seed and seedlings from treated seed in field soil showed that the fungi that significantly reduced survival were F. andiyazi, F. cerealis, F. oxysporum, P. longicolla and all the Pythium spp. Seed treatments TR1 and TR2 significantly increased survival of seedlings in soil inoculated with F. andiyazi and although seed treatment TR3 also significantly increased survival, it was less effective. Seed treatment TR2 was also less effective compared to TR1 and TR3 to increase survival in soil inoculated with F. oxysporum. For P. longicolla and all the Pythium spp. all three seed treatments TR1, TR2 and TR3 effectively controlled damping-off. In the present study none of the Rhizoctonia isolates obtained caused significant damping-off. Fungicide seed treatment is a common practice for managing soilborne, seed, and seedling pathogens. Evaluating seed treatments for control of soilborne diseases under glasshouse conditions allows the evaluation of single pathogens which is important to determine the efficacy against some of the most important soilborne pathogens. However, since these products are ultimately intended for management of soilborne pathogens under field conditions it is essential to evaluate seed treatments under field conditions. It is well-known that there is a complex of soilborne pathogens that affect soybean in field soil and that these complexes differ in different production areas and are affected by different soils and climatic conditions. From this report it is also clear that there were cultivar by seed treatment interactions indicating that certain treatments may be more beneficial to certain cultivars than others and certain seed treatments are better suited to certain production areas than others. The challenge is to identify a seed treatment that will benefit establishment and yield of most cultivars in most production areas under both dryland and irrigation systems. During the 2017/18 season the three seed treatments will be evaluated again on three soybean cultivars in the cool, moderate and warm production areas, to confirm results that seed treatment has the potential to increase seedling survival and grain yield of soybean in South Africa.

4. Etiology and population structure of Macrophomina phaseolina (charcoal rot) in sunflower and soybeans in South Africa

   Ms E Jordaan and Prof JE van der Waals
   University of Pretoria

   This project investigates interactions between the environment, host (sunflower and soybeans) and Macrophomina phaseolina causing charcoal rot in South Africa. The main objective of this work is to understand the drivers of this disease in order to develop a decision support system for charcoal rot management. In vitro trials, pathogen identification, characterization and greenhouse pot trials will be used to create a holistic picture of charcoal rot on in SA. The results from the in vitro trials have been discussed in previous reports. Unfortunately, the planned grower survey had to be removed as we were unable to obtain enough feedback to make statistically sound conclusions regarding growers' perceptions, the occurrence of this disease and the subsequent control practices that are in place in South Africa. Isolate identification is underway, after several unforeseen setbacks.

   Greenhouse pot trials were conducted to investigate the effect of drought on charcoal rot incidence and severity in soybean and sunflower crops and subsequent yield reduction. Although the results have not been statistically analysed yet, results from the water stress trial showed there was no disease incidence for either sunflower or soybeans at seedling stage. Latent colonisation within the stems was found up to 1cm above the root zone even in plants that were not water stressed, suggesting that drought conditions are not required for infection. During flowering, colonisation was measured up to 2cm above root zone for soybean and 3cm for sunflower. No disease was observed in the sunflowers, which could be due to tolerance within the cultivar planted. In soybeans, disease was observed at flowering in both the water stressed and non-water stressed treatments – the latter with lower severity. At harvest disease incidence and severity were high in the inoculated and water stressed soybean and sunflower plants, and stem colonisation was observed 3cm up the stems in all inoculated plants irrespective of water stress. Yields from the water stressed non-inoculated plants as well as the water stressed inoculated plants were half that of the yields from the control plants (non-inoculated and non-water stressed). Plants that were inoculated but not water stressed showed similar yields to that of the control. Another pot trial evaluated the effect of urea and limestone ammonium nitrate (LAN) applied pre-plant at the recommended rate (15kg/ha for soybeans; 50kg/ha for sunflowers) and half the recommended rate on disease development. For soybean, long and medium growth class cultivars were selected and for sunflower medium and medium-late seasonal cultivars were selected. Results have not been statistically analysed yet, however growth, stem width, total nitrogen and number of seeds/pods seemed to be unaffected by the pathogen under the different N applications in different growth habit cultivars. The pathogen colonised soybean and sunflower stems up to 3cm from the root zone throughout all the treatments. No disease was observed and higher yields were recorded in the long growth class soybean cultivar that did not receive nitrogen pre-plant. Higher disease incidence and severity were associated with urea applications in soybeans. In the sunflower trial disease incidence and severity were higher in the medium cultivar than in the medium-late cultivar irrespective of the nitrogen applications. No disease was observed in medium-late cultivar sunflowers treated with LAN at half the recommended rate or urea at the recommended rate.

   For the decision support system, historical weather data, literature mining and various calculations were utilised. The optimal growing temperatures of South African M. phaseolina isolates were found to be between 25 and 30ºC. Coupled with the reduced rain and constraints on irrigation we would expect higher incidence of this disease than in rainy seasons. There is very little information available on the incidence of charcoal rot on sunflower or soybeans in terms of location and year of outbreak. However, during the 2011/2012 growing season where losses in maize due to charcoal rot of up to 60% were recorded. For this reason, the decision support system model will be based on maize data, using the 2011/2012 incident to validate the model. From this the model can be adjusted for sunflower and soybean crops.

   Future research from this project could be focused on investigating epidemiological aspects of the disease to refine the decision support system for use at farm level. A lay article on this disease and research was published in The Conversation in August 2016: Charcoal rot: a threat to staple food crops in South Africa.

   Upon completion of the project, results will be published in peer reviewed articles in scientific journals, articles in local media such as Farmers Weekly and Oilseeds Focus, and presented at farmer days.

5. An evaluation of continuous cash crop production (including small grains, canola and other alternative broadleaf crops) under conservation agriculture principles on high potential soils of the Riversdale Flats

   JA Strauss
   Western Cape Department of Agriculture

   2016 was the 5th year of continuous cropping research at the Riversdale site. Six cash crop systems are tested including shortened canola rotations and cover crops. A total of 60 plots are planted. The 6 systems tested are replicated 3 times and all crops within each system are represented on the field each year.

   Riversdale received excellent summer rainfall of just over 200mm in the pre-season which resulted in enough available moisture to plant at the end of April. Unfortunately there were issues with the rainfall data generated by the ARC weather stations and we could not get an accurate description of the rainfall through out the production season. General indication was that the rain during the 2016 production season was less than average. The Western Cape Department of Agriculture has invested in our own weather stations at all the main crop rotation trial sites.

   Hyola 555 was planted at Riversdale at 3.9kg/ha. A total of 45kg N/ha was applied to each plot (24kg N/ha at planting and 21kg N/ha top-dressing). Canola plots following the legume cover crop did not receive the topdressing. Canola yields at Riversdale averaged 2 275kg/ha with all plots showing oil yield above 43%. Canola yields ranged from 1 324kg/ha to 2 833kg/ha. This was on average 855kg/ha more than the 2015 season (1 420kg/ha) and 845kg/ha more than the 2014 season (1 430kg/ha). The canola following the legume cover crop in the system cover crop – canola – wheat has outperformed the canola in other systems every year since the inception of the new rotation systems at the Riversdale site, even when other plots received an extra topdressing.