S14 - Session P6 - Control of Heterodera carotae in soil by a resistant carrot genotype

Authors: Olivier Vimont *, Laure Barrot, Stéphanie Mallard, Julien Sacré

Heterodera carotae is a carrot cyst nematode widespread in Europe. This carrot parasitic worm is responsible for significant yield losses, (up to 80% in sandy soil). Symptoms are characterized by a reduction in the root size and a strong production of lateral roots, giving a rather characteristic hairy appearance that sharply depreciates the product, making it unmarketable. Considerable efforts have been expended to control carrot cyst nematode without using nematicides: solarization, steaming, crop rotation or biological methods. Nevertheless, chemical control appears to be one of the most economical control method against H. carotae and still one of the most efficient ways to limit yield losses. However, in a context where the growing conditions must be more respectful of the environment, these chemical treatments are no longer accepted; as a result, 1, 3 dichloropropene was banned in 2009 at the European level, leaving farmers with no effective solutions. The current context is prompting to seek new options to reduce H. carotae populations in soils. Since early 2000's Vilmorin-Mikado performed a research project to propose new solutions. We have developed a new resistant genotype that can block male larvae at juvenile stage in root, preventing almost any multiplication of the nematode. The effectiveness of this resistant genotype was tested against the carrot cyst nematode in artificial and field conditions. Results show significant reduction of H. carotae population in the soil (from 40% to 80% upon test conditions and time) and increase in marketable yield (+28% compared to untreated control in field condition). Therefore, with substantially identical disinfection rates than those obtained by chemical disinfection this resistant genotype could be an effective and innovative strategy for disinfection of contaminated soil by this cyst nematode. The operational deployment of this new solution is currently in active development.