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Technical workshop in Almeria and Murcia

BASF's renewed iceberg portfolio to tackle Bremia and Fusarium

BASF | Nunhems recently brought together a hundred professionals from the lettuce production and marketing sector. Under the title 'The best solution for Bremia and Fusarium', the debate focused on how to tackle both issues in the Region of Murcia, Spain's main production area, with more than 420,000 tons annually.

In the case of Bremia, in July 2023, the International Bremia Evaluation Board (IBEB) identified three new strains (Bl: 38EU, Bl: 39EU, and Bl: 40EU). As for Fusarium, although it has been present in the fields for years, it has been detected more often and in unusual areas in the last few campaigns.

"Up until the 2023 campaign, the most affected areas were the northwest, the Guadalentín Valley and the Altiplano," said María del Mar Guerrero, a researcher at the Murcian Institute for Agricultural and Environmental Research and Development (IMIDA). However, "this year it has been detected for the first time in the Campo de Cartagena, thus threatening also the cultivation area in this region."

The Fusarium oxysporum f. sp. lactucae is a soil and vascular fungus that enters the plant through the roots and moves up to the vascular bundles, causing darkening of the vascular system, yellowing of the outer leaves and necrosis. The final result is "a slowdown in growth and death of the plant," said Guerrero.

Until now, summer crops were the most affected, but in recent years, there have been reports also in autumn and even part of the winter; a consequence of increasingly mild temperatures. Moreover, according to the IMIDA researcher, "the problem could get worse," especially due to two fundamental issues: on the one hand, the accumulation of inoculum in the soil; and on the other hand, the fact that the plantings are being advanced to warmer periods.

Among the solutions proposed to tackle it, Guerrero pointed to soil biosolarization to reduce the presence of inoculum before the planting, and the use of genetically resistant varieties.

A renewed portfolio
"When a new strain of Bremia appeared two years ago, we started focusing on the development of varieties able to resist it," said Gregorio Pérez-Crespo, Principal Local Product Specialist Leafies Iberia & Team Lead Trial at BASF|Nunhems.

Today, the seed house boasts a renewed portfolio of iceberg lettuce varieties with full resistance to Bremia (16-40) and to Fusarium (Fol) 1 and 4. With them, it covers the transplant cycle from early autumn to early spring, providing greater security to the producer and the marketer.

The new iceberg lettuce varieties from BASF|Nunhems have performed well in the last two campaigns, even against bacteriosis, especially soft rots.

This problem is rare in the Campo de Cartagena, but with the right weather conditions, it can appear. "When that happens, it does so unexpectedly, causing significant damage in the short term," said Daniel Bellón, Senior Scientist at BASF|Nunhems.

The iceberg is the most sensitive variety to this kind of bacteriosis due to its greater contact with the soil, which leads to the appearance of chlorotic and, subsequently, necrotic leaves, with a soft rot.

This type of bacteriosis is common in potato cultivation, which is deeply rooted in the Campo de Cartagena. BASF|Nunhems' recommendations include not rotating lettuce crops in soils where potatoes have been previously cultivated. Moreover, "where possible, it is preferable not to use thermal blankets, as they facilitate its growth."

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