New Plant Pathology chair at Stellenbosch University

Post-harvest expert Dr Cheryl Lennox discusses the challenges facing the industry and her vision for the Department.

Dr Cheryl Lennox completed her PhD in plant pathology at the University of KwaZulu-Natal before first joining Stellenbosch University in 1991. In 1995, she relocated to Oregon State University, where she researched post-harvest pathology. On her return to South Africa, she worked at the Agricultural Research Council, rejoining the Department of Plant Pathology at Stellenbosch University in 2008.

Hortgro caught up with Lennox at the start of another hectic academic year.

Q. What are your main research interests?

A. I have a research programme on the management of post-harvest diseases that complements the other sections within our Department very nicely. I mainly focus on pome and stone fruit and citrus — so tree fruit of our region. More recently, I have PhD students working on post-harvest disease management of tomatoes.

There’s a risk that after the fruit have been harvested looking beautiful, it goes into storage and then loses quality after storage or during export — that’s where my research focuses.

I look at how we can best manage post-harvest diseases in especially our export crops. It includes biological control, appropriate use of fungicides, monitoring fungicide sensitivity, and looking for new diseases that might pop up because of climate change.

Q. What challenges does the fruit industry face?

A. I think one of the big challenges is the shift away from synthetic fungicides. Until relatively recently — and even now — we relied largely on fungicides to manage our post-harvest diseases. But there’s a worldwide shift to reduce the chemicals we use — the chemical load and the number of chemicals.

That is a big challenge because how do we still provide good quality fruit? The tools we’ve had up to now worked reasonably well in most cases. So now we’re looking for alternatives to synthetic fungicides. We’re looking for biocontrol agents — either the living organisms or their products — and their appropriate uses of them.

Also, if we’re still using fungicides, we need to know when we can use them so that we’re still satisfied that we get good quality fruit — when is the appropriate time for using that particular chemistry. So, we need to integrate other tools like forecasting models and remote sensing to know exactly when to use a particular fungicide for what target pathogen.

I think those are big challenges for pathology in general but specifically for post-harvest diseases because, with post-harvest diseases, we are so close to consumers eating or being exposed to the product. The demand for disease control at that stage is very high, but that’s also the stage at which people can detect the presence of chemicals such as fungicides.

Q. Are logistical issues and load-shedding increasing post-harvest risk?

A. They put pressure on the storage facilities and on reducing the time between harvesting and getting fruit into the right storage conditions. And then also on maintaining those conditions. There is also the added cost of alternative ways of keeping refrigeration processes going.

And quite often, when we’re looking at alternative controls, many of them don’t work as well as synthetic fungicides when used as stand-alone treatments. So now we introduce the added factor of temperature not being as well-controlled, which makes it even worse when we’re looking for alternatives.

Q. How do you see your relationship with the fruit industry?

A. As researchers within the Department, we really do value the contribution that our industry partners make. We can do our academic work — we can teach — without industry funding, but to have postgraduate students, we must have funding through our industry partners. Even at the level of an honours student, each project has a cost.

Of course, it’s also through our industry partners that we keep in touch with our research areas and identify directly related projects.

Q. What are your plans for the Department?

A. For a while, it’s been a well-functioning department. And within the Department, each person generally gets on with their own research area and postgraduate students. We each manage our own funding for our research projects.

What I would like to see is a bringing together of everybody. I think we’re isolated from each other — we all identify ourselves as limbs of the Department, but I would like to see us come together as the body of the Department.

I would like people to know what other people are doing and where we can add value to each other’s projects — I’d like a bit of synergy within the Department itself.

And even beyond that, there are so many closely related fields to plant pathology, and for me, it’s important that we also involve agronomy, soil science, etcetera. We’re doing that in our individual capacities, but I’d like to see us doing it as a department.