Southern African Society for Plant Pathology - Soilborne Diseases Workshop 2004

The Soilborne Plant Diseases Unit of the Agricultural Research Council’s Plant Protection Research Institute hosted the 14 th interdisciplinary symposium on soilborne plant diseases on 15 and 16 September 2004 at the Vredenburg Research Centre of the ARC-PPRI in Stellenbosch. The topic for this year’s symposium was Crop Rotation and Soilborne Plant Diseases and was attended by 60 representatives of Research Councils, National and Provincial Departments of Agriculture, private companies and universities. Participants represented a wide range of disciplines such as agronomy, botany, entomology, horticulture, microbiology, nematology, plant pathology, and soil science.

Participants in the Symposium of the Soilborne Plant Diseases Interest Group included:
Front row, from left: Z. Dawood, C.M. Lubbe, B.C. Flett, J.H.S. Ferreira, M. Molope, K.W. Pakendorf, S.C. Lamprecht, J. de Kock, A.A. Nel, J.L. Staphorst, C.L. Lennox, E.E. Buntting;
Second row: B. Nel, S. Tweer, A Belgrove, L.V. Serage, J. Moen, E. Carstens, S.G. Storey, E.R. Van Biljon, I. Bezuidenhout, C. du Preez, A. Swanepoel, J.F. Bloem, T.A.S. Aveling, S. Steenkamp, R. Gouws, A. McLoed, A. Steyn, N. Ramdheen, L. Van Schoor;
Third row: J.J. Serfontein, F.G.H. van Zyl, S.J. Verwey, A. Fourie, W.J. Loubscher, S.H. Koch, H.J. Hugo, I. Tshivhandekano, L.V. Mudau, G.J. van Coller, R. Knoetze, M.C. Pretorius, P. Cadet, A.H. McDonald, L. Grundlingh, K. Bothma;
Fourth row: J.H. Habig, J.C. Janse van Rensburg, Y. Tesfai Tewoldemedhin, F. Halleen, A.J. Cilliers, A. Viljoen, P.J. Pieterse, G. Trytsman, V. Spaull, N.W. McLaren, J. Allemann, D.J. Beukes.

Crop rotation: A cornerstone of sustainable crop production.
Crop choices in rotational production systems.
Cropping systems for new crops: an ecological perspective.
Legumes and biological nitrogen fixation in crop rotation.
The use of crop rotation in rural agriculture.
Crop rotation and soilborne diseases.
Effect of crop rotation on crown rot and the incidence of Fusarium pseudograminearum in wheat.
Functional diversity of soil microbial communities in disease conducive soils subjected to crop rotation.
The effects of crop rotation on soil properties in relation to agriculture: an overview.
Crop rotation and weed management: principles and practices.
The need for crop rotation for managing nematode problems.
Crop rotation as part of an integrated pest management programme for the control of plant parasitic nematodes.
The effect of intercropping and organic amendments on nematodes and rain-fed sugarcane in a small scale farming system in Kwazulu Natal.
Crop rotation for the control of Verticillium wilt in cotton.
Controlling soilborne diseases by using rotation crops with biofumigation potential.

Dr Andre Nel of the ARC-Grain Crops Institute delivered the keynote address in which he presented a short historical background to crop rotation and discussed the causes of the observed “rotational effect”.

Conclusions reached by the delegates to this symposium can be summarized as follows:

Crop rotation, practised correctly, has significant ecological and economical benefits and is therefore a prerequisite for sustainable agriculture.
Crop rotation has an enormous potential for effective management of soilborne plant diseases. It is, however, important that crop rotation be practised as part of an integrated management strategy against these diseases.
There is no one-size-fits all crop rotation system. A producer needs to experiment with various options, and understand specific requirements of the farm as well as potential markets before diversifying.
Crop rotation can play an important role in improving and maintaining soil health, thereby contributing to soil productivity and sustainability.
Conservation tillage challenges monoculture in that inoculum builds up over time. Successful disease management using crop rotation depends on understanding and accommodating the longevity of inoculum and the wide host ranges of some soilborne pathogens.
Use of cover crops has increased over the past decade because of an increased environmental awareness and a shift to organic farming. This interest in cover crops necessitates the identification of suitable cover crops.
“New” crops can be introduced into cropping systems if their use is evaluated beforehand , but often not enough is known about their production or how to manage them in cropping systems . This can be solved only through research, which is poorly funded at this stage due to the perceived minor importance of these crops.
Practices to evaluate the host range and specificity of plant parasitic nematodes should be standardized in South Africa, and susceptibility of new cultivars to nematodes should be evaluated on a continuous basis.
A database for the host status of plant parasitic nematodes in South Africa should be compiled as a matter of urgency.
Incorporation of brassica residues in disease control practices can be an innovative means of managing soilborne diseases that is effective, economically feasible and environmentally friendly when applied and managed effectively.
Although crop rotation with non-hosts is perhaps the most effective means of soilborne plant disease control, research in this field is limited. This is probably a reflection of the current emphasis on of short term instead of long term research funding , which mitigates against research on crop rotation. It also underscores the focus of commodity groups on their own commodity at the expense of studies on crop rotation.
The complexity of selecting appropriate rotation systems for optimum disease management, productivity and economic benefits emphasizes the need for increased, multidisciplinary collaboration

The fourteenth symposium of the Soilborne Plant Diseases Interest Group of South Africa was held on 15 and 16 September 2004 at the Stellenbosch Research Centre of the Agricultural Research Council’s Plant Protection Research Institute in Stellenbosch. The theme of the Symposium was: Crop rotation and soilborne plant diseases. The keynote address was delivered by Dr Andre Nel from the ARC-Grain Crops Institute, South Africa .
Other speakers at the symposium were:
Front row, from left: Dr A.J. Cilliers (sponsor, Plaaskem), Dr J.L. Staphorst (Deputy Director, ARC-Plant Protection Research Institute), Dr M Molope (Group Executive Officer of Public Support Services, ARC), Dr S.C. Lamprecht (organiser and speaker, ARC-Plant Protection Research Institute), Dr J. de Kock (sponsor, Protein Research Foundation), Prof. K.W. Pakendorf (University of Stellenbosch);
Middle row: Ms S.G. Storey (Nemlab), Ms E.R. van Biljon (ARC-Institute for Industrial Crops), Ms A. Swanepoel (ARC-Institute for Industrial Crops), Ms J. Bloem (ARC-Plant Protection Research InstituteI), Ms R. Gouws (ARC-Roodeplaat Vegetable and Ornamental Plant Institute), Dr P. Cadet (South African Sugarcane Research Institute-Research Institute for Development);
Back row: Mr K. Bothma (sponsor, Plaaskem), Dr B.C. Flett (ARC-Grain Crops Institute), Dr J. Allemann (University of the Free State), Dr P.J. Pieterse (University of Stellenbosch), Dr A.A. Nel (ARC-Grain Crops Institute), Mr J.H. Habig (ARC-Plant Protection Research Institute). Absent: Dr D.J. Beukes (ARC-Institute for Soil, Climate and Water), Mr G. Trytsman (ARC-Range and Forage Institute), Mr M.J. Southwood (sponsor, Hygrotech) and Dr N Kotze (Sponsor, Agricol).

Fourteenth Annual Symposium Of The Soilborne Plant Diseases Interest Group Of South Africa