Estival lettuce

Jenni, S. and Emery, G. C. 2009 Estival lettuce. Can. J. Plant Sci. 89: 99-101. Estival is a heavy crisphead lettuce highly tolerant to bolting under long day growing conditions (more than 13 h). Estival is the first Vanguard-type lettuce released by the Horticultural Research and Development Centre (HRDC) lettuce breeding program of Agriculture and Agri-Food Canada (AAFC), Saint-Jean-sur-Richelieu, Quebec. Very similar in appearance to Summertime, Estival is well adapted to organic soils. Estival is more tolerant than Ithaca (the regional standard) or Summertime to rib discoloration, a physiological disorder caused by high-temperature growing conditions.