Three decades breeding peppers resistant to Phytophthora capsici in Argentina.

GALMARINI, C.R.

Viña del Mar

Conferencia; 22nd International Pepper Conference; 2014

INIA

The consumption of fresh and dehydrated peppers has increased in many countries during the last decades; Argentina has not been the exception to this tendency. Phytophthora capsici is a soil-born oomycete plant pathogen that limits pepper production worldwide. Root rot of pepper caused by P. capsici was first reported in 1940 in Argentina and is one of the most serious factors limiting pepper production, especially in irrigated zones of Argentina. In some years nearly 40% of the production has been reduced due to this disease. P capsici is heterothallic requiring A1 and A2 mating types to produce sexual oospores and in many populations it appears that dormant oospores can provide a source of inoculum for an extended period of time The P.c. population structure varies significantly depending on the location; In Argentina, so far, all the isolates that we have studied belong to one mating type (A1) and are sensitive to mefenoxam. Recommended management strategies for P. capsici include cultural practices that ensure well-drained soils in the field, crop rotation, soil solarization, use of mulches to prevent splash/soil dispersal, and chemical control. The use of P. capsici-resistant pepper cultivars is an important aspect in the management of this disease. At La Consulta Experiment Station of the National Institute of Agricultural Technology (INTA), a breeding program has been conducted for more than 30 years to introduce resistance against local strains of P. capsici in both bell and heart-shape-type peppers. In all cases, an accession from Dr. P. Smith of the University of California, Davis was used as the initial source of resistance. Different virulent isolates of P. capsici were used in controlled inoculation tests, and under field conditions. As a result of the program, the resistant bell-type cultivars Fyuco INTA and Lungo INTA as well as resistant heart-type cultivars for the cannery industry, Calafyuco INTA and Don Humberto INTA, have been released. Nowadays, the main goal of the program is to introduce P. capsici resistance to paprika cultivars, resistant advanced lines with good agronomic characteristics are being evaluated in several locations. The resistant cultivars released by INTA La Consulta, such as Fyuco INTA and Calafyuco INTA, are still widely used by pepper growers and the limited genetic variation in the pathogen population may be a factor that allows disease resistance to remain viable for extended periods of time.