Behavior of potato cultivars grown in the organic production system in southern Brazil, under Late Blight and Corn Rootworm larvae damage incidence

Resumo

In this research we evaluated the adaptability of potato cultivars to organic production and identified those more productive and less damaged by P. infestans (LB) and D. speciosa. The experiment was conducted under organic cultivation during the 2013/2014 (Year 1) and 2014/2015 (Year 2) crop seasons, evaluating the cultivars (i) Ágata, (ii) IAC Aracy Ruiva, (iii) IAC Vitória, (iv) BRS Clara, (v) BRS Eliza, (vi) EPAGRI 361 - Catucha and (vii) IPR Cris. In both years, we assessed: LB severity and area under disease progress curve (AUDPC), external holes and internal galleries caused by D. speciosa larvae, and total tuber yield. Potato cultivars showed adaptability to the organic system, yielding more commercial than non-commercial tubers. Most cultivars reacted positively to P. infestans and D. speciosa. Agata was the most susceptible cultivar, with LB severity close to 100% and AUDPC significantly higher than the other cultivars. LB severity and the AUDPC were below 20% in the first year and between 20 and 70% in the second year for the other cultivars. D. speciosa larvae external damages were more intense in 'BRS Eliza' than in 'BRS Clara' and 'EPAGRI 361 Catucha'. 'BRS Eliza' was also among the most internally damaged cultivars in both years, while 'EPAGRI 361 Catucha' and 'IAC Vitória' were among the least internally damaged. The multivariate analysis allowed us to indicate 'EPAGRI 361 Catucha' and 'BRS Clara' as the most suitable for organic cultivation in the Southern Brazil, among the materials studied.