In the last few years, the fungus Stemphylium (and Stemphylium vesicarium in particular) has become one of the biggest challenges for spinach producers worldwide. The spinach breeding programs of the vegetable breeding company Rijk Zwaan are focused on developing varieties resistant to this fungus. Preliminary results of an ongoing study by Washington State University in the USA have confirmed that this focus in recent years has resulted in a large number of spinach varieties highly resistant to Stemphylium vesicarium.
Need for clear and accurate information
According to Rijk Zwaan, the presence of more than one species of Stemphylium that causes leaf spots in spinach can lead to confusion about the different strength levels. “Some spinach producers are very concerned about the development of this disease. Wim in 't Groen, Spinach Product Coordinator at Rijk Zwaan, says that clear and accurate information is needed on this subject.
high infection
In the fresh produce market and in the processing of spinach fields, Stemphylium vesicarium is currently the most common pathogenic Stemphylium species found in most production areas and causes infection in susceptible spinach varieties. To learn more about this plant disease, a group of researchers affiliated with Washington State University and led by Professor Lindsey du Toit started a new study on this fungal disease in 2019.
Promising preliminary results in Rijk Zwaan spinach varieties
Du Toit is no stranger to the field, as his program has conducted several studies on Stemphylium in the past. His latest and ongoing research shows that a number of Rijk Zwaan cultivars have a clearly visible high level of resistance to Stemphylium vesicarium. This finding is not surprising to Rijk Zwaan, but vegetable breeding companies need clarity on this issue.
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More information available
Due to the ongoing work, the final results will not be published for a while. Spinach producers who want to learn about the varieties included in the study can contact Rijk Zwaan's spinach crop experts.
Resistant spinach varieties
The extensive Rijk Zwaan spinach catalog already contains a large number of spinach varieties with a high level of resistance to Stemphylium vesicarium. This product range will continue to expand in the years to come as the company focuses and prioritizes its spinach R&D program. Some of the known high-strength Rijk Zwaan cultivars are SUNANGEL RZ F1 and CABEZON RZ F1 from the savoy cultivar, and the flat-leaved KODIAK RZ F1 cultivar.
R&D
Developing resilience is one of the priorities in Rijk Zwaan's R&D programme. On average, the vegetable breeding company invests about 30% of its turnover in R&D. A significant part of this is spent on developing resistance to both new and existing plant diseases. As a result, Rijk Zwaan not only relieves the burden on its partners, but also contributes to a more sustainable food chain with less waste and greater efficiency.