Expert chat with Prof. Richard A. Sikora, Professor Emeritus, University of Bonn, Germany – March 2017

Prof. R. A. Sikora
Professor R. A. Sikora

Richard A. Sikora is Professor Emeritus and former Head of the Soil-ecosystem Phytopathology Department at the University of Bonn in Germany. He received his Ph.D. in 1970 from the University of Illinois and began his international experience as a USAID-supported Visiting Assistant Professor at Govind Ballabh Pant Agricultural University in India. His rich experiences reach from soil ecology and biology to agronomy and plant pathology.

Richard, can you briefly summarize your professional history and passion?

I have worked in nematology since I was 22 years old – and by now have been in the field for almost 50 years!

I started working on aquatic annelid worms as bioindicators for water pollution during my master’s study. In 1967, I began doctorate work on nematodes in turf and soybean at the University of Illinois. After that, I wanted to see the world and went to India as an Assistant Professor for plant pathology, where I worked on vegetables, wheat and rice. From India, I took on a postdoc position and later assistant professorship at the University of Bonn in Germany. My position at the University of Bonn focused initially on the interaction between nematodes and plant pathogens, as well as between nematodes and mycorrhiza. In 1990, I received full professorship for integrated pest management in the tropics and subtropics and became strongly involved in international agriculture, working with the FAO, the German Development Service and the Consultative Group on International Agricultural (CGIAR). Over 40 years as an active University of Bonn Professor, I supervised more than 90 Ph.D. students and 75 master theses which resulted in more than 300 publications, 40% of which relate to tropical and subtropical problems.

Since retirement, I have been active in topics that have always been close to my heart. I still work occasionally as an international consultant for the CGIAR, The German Development Service and several companies. I also convene a think-tank about the impact of sustainable intensification on food security, human well-being and the environment in southern Africa for the Stellenbosch Institute for Advanced Studies (STIAS) in South Africa. I had a good life and exciting career and now feel I should give something back to society, especially to countries in the tropics and subtropics. I think with my plant pathology expertise, I am in a good position to help where it is needed.

You have been involved in nematology for such a long time – what has changed?

There have been a lot of changes, especially in the last 10-15 years. First of all, it has to be said that the agricultural world is basically divided into two groups:

  • Big (family) farms such as in the US, Europe, Australia, and Brazil and
  • Small family farms that are usually smaller than 5 hectare (ha). These farms account for 90% of the farms in many tropical and subtropical countries.

In the big (family) farm business, agricultural technology has moved to shorter rotations, resulting in nematode population build up. We have lost a lot of potent nematicides in the past due to their toxicity and environmental impact. Although today’s farmers have resistant cultivars in their hands, populations with new virulence can overcome those traits.

It has also become more and more difficult to actually recognize nematode damage when crops are grown under optimal conditions with respect to water availability and fertilizer. In many cases, the high yielding cultivars being grown have a very strong masking effect on developing nematode problems.

With the move to increase development and use of molecular tools, which are helpful in breeding, we lost a large number of applied nematology positions in universities and other institutions to molecular biologists. This is not necessarily bad because the molecular tools developed were able to show that nematode populations are often mixtures of species – and what we thought of before as one species might not necessarily be just one. Molecular biologists have also added greatly to our knowledge of plant resistance and detection of new traits.

Companies are now talking about new traits that are going to come to the market, as well as new nematicides that are actually entering the market. Importantly, the advances in nematicide development involves new modes of action and compounds that can often be used as seed treatments that reduce early root infection. What has also been a revolution in nematology recently: remote sensing tools that allow estimating the Pi of a nematode population in a given field from airplanes, satellites or drones. Another approach uses soil conductivity differences in a field for more targeted nematicide application, which is possible because different nematodes favor different soil types.

With respect to the second group of the agricultural world – small farms – a clear trend to even smaller farms of less than one ha is observable. This trend makes it even more challenging to develop management practices because we do not have a good understanding of what is going on in many of these small farm cropping systems. On top of the size of the farms, it is hard to reach the large number of farmers through extension. Maybe modern information technology will help since all these farmers have cell phones and therefore could have access to extension information.

On these farms, two to three crops are usually grown in one year and sometimes even more. Rotations also include perennial crops like banana and papaya that maintain nematode populations (e.g. root knot nematodes) on extensive root systems growing under the annual crops that are intercropped in the same field. Growing rice in a rotation usually reduces the nematode problem through flooding and associated anaerobic conditions. This is an important plus for many crops in Asia e.g. in wheat-rice rotations. As a result of these trends, we face a big problem: how can we adapt the new knowledge we have developed to support those small farms?

One answer is that we need to have more nematologists in the tropics and subtropics.

If you could recommend (only) one book to someone who is new in the field of nematology, which would you recommend?

That depends to some extent on what part of the world the person is working and their basic knowledge of nematology.
If I could recommend only one book then it would be one of the two I consider introductory books:

Plant Nematology; R. N. Perry & M. Moens (2006)
CABI Publishing: Wallingford, UK. 447.
ISBN-10: 1-84593-056-8; ISBN-13: 978-1-84593-056-1. Price, £55, $US100

and the second:

Practical Nematology; Rosa H. Manzanilla-López, N. Marbán-Mendoza (2012).
Published in both English and Spanishy

I use these texts to teach masters students. They give a deep general understanding from taxonomy, ecology, and quarantine to control methods (biological, chemical, resistance). The first book goes into more detail on the basics of nematology; the second is a good book for those interested in applied nematology.

If someone already has a background and basic knowledge, but needs information on practical nematology for a specific crop or crops, I would suggest the following book for people working with nematodes under temperate conditions:

Plant parasitic nematodes in temperate agriculture; K. Evans, D.
Trudgill and J. Webster (1993)
CABI Publishing: Wallingford, UK. 447.
ISBN-10: 0851988083 ISBN-13: 978-0851988085
Price: 90 €

For people in the tropic and subtropics, I would recommend a book that I have edited since 1990 and am currently revising with some younger colleagues for the third time (available from 2018):

Plant parasitic nematodes in subtropical and tropical agriculture;
M. Luc, R. Sikora and J. Bridge. (2005, new revision 2018)
CABI Publishing: Wallingford, UK. 447.
ISBN: ISBN 0-85199-727-9

Another good practical hand book directed at methodology is this one:

Practical plant nematology: a field and laboratory guide; D. Coyne, J.
Nicol and B Claudius-Cole (2009 new reprint 2014)
ISBN: 978-978-8444-40-4

This guide was produced by the International Institute of Tropical Agriculture (IITA) and the International Maize and Wheat Improvement Center (CIMMYT) as part of the strategy of the Systemwide Program on Integrated Pest Management (SP-IPM) to improve the quality and usefulness of pest management research.

Online versions are available here:,+J.&ots=Go9__dnYXG&sig=Obz3L7QzZXlCx0Whaj2_q21k8ZA#v=onepage&q&f=false

These are the books I used in my courses. Of course, there are many more good books, most more specialized and targeting basic research.

One thought on “Expert chat with Prof. Richard A. Sikora

  1. Prof sikora is an excellent mentor in nematology. I personally worked with him in Bonn in early 90s.

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