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Our head lettuce

Hochelaga

Hasty variety, with a maturity of 1 to 2 days before Ithaca. Produces particularly heavy and compact heads. Resistant to bolting in long-day growth conditions. Very good resistance to rib discoloration. It develops as many symptoms of tip burn as Ithaca, under conditions conducive to the development of this disorder. Short harvest window. Well suited to fresh market.

Estival

Vanguard type variety, with rounded outer leaves, medium to thick, dark green. Produces heads of good weight, homogeneous with a small-size heart. Adapted to extreme climatic conditions, it is resistant to rib discoloration and bolting, and tolerant to tip burn. Offers a good waiting time in the fields. Large harvest window from late June to late September.

High quality lettuce variety, suitable for both fresh market and processing. A proven variety, having received the "Seed of the Year Award" at the Toronto Royal Agricultural Winter Fair in November 2010.

AAC Champlain

Great Lake type variety, such as Ithaca, with broad outer leaves, medium thickness, light to medium green. It produces large, heavy heads, on a short stem. A good head configuration with few protruding ribs. More hasty than Ithaca and resistant to bolting. It develops fewer rib discoloration symptoms than Ithaca and shows fewer tip burn symptoms than Hochelaga. Suitable for hot conditions. Harvest segment from late July to early September. Ideal for the fresh market.

AAC Canicula

Vanguard type variety, broad outer leaves, medium to thick, medium green. Produces high head weight with a very short heart. Maturity similar to Estival, 1 day earlier. Highly resistant to bolting, has less incidence of rib discoloration than Estival and Sun Devil, with a moderate tolerance to tip burn. Underside slightly pointed. Suited to harvest segments from June to mid-July and from mid-August to early October. Suitable for fresh and processing markets.

AAC Richelieu

Great Lake type variety with broad outer leaves, medium thickness, medium green. Produces large heads with excellent filling capacity, ensuring a good density and a very good weight, which allows earlier harvest under stress conditions. Hasty variety, comparable to AAC Champlain from 1 to 2 days. In addition to being resistant to bolting, it is tolerant to rib discoloration and tip burn. Heat-loving variety, suitable for summer harvesting between late July and late August.

AAC Global

Vanguard type variety, Global is recognized by its rounded outer leaves, moderately shiny, of medium green color. Produces a very good size head, dense, heavy, with a short heart. Slightly earlier than Estival. It offers excellent tolerance to rib discoloration and tip burn, and is very resistant to bolting. The base of the head is sharper than that of Estival, which is flat. Can be produced over a long period, from July to early October. A good choice for both fresh market and processing.

AAC Johral

A Vanguard-type variety, recognisable by its medium to dark green leaves with a slightly blistered top. At harvest maturity, it produces heads of good size, with a dense interior and a short core. Under warm growing conditions, shows less symptoms of rib discoloration and tip burn. It reaches maturity two to three days before Estival. Well suited to fresh and processing markets.

Our Lettuce

Diseases

Telluric and bacterial diseases

Bacterial leaf spot

Bacterial leaf spot due to Xanthomonas campestris pv. vitians first appears as oily-like spots on the leaves margins, which in a few days become necrotic and confluent. When conditions are favorable, the spread of the disease is very fast and devastating. The lack of licensed chemicals in Canada makes it difficult to control and copper-based bactericides are ineffective.

Current research, in collaboration with Saint-Jean-sur-Richelieu's CRD, aims to identify strains of Xanthomonas in lettuce production areas, determine their frequency, distribution and pathogenicity. Research projects conducted with VRIC aim to develop molecular markers of resistance to bacterial spot. The Foundation continues to focus on preselecting cultivars and non-advanced lettuce lines to identify sources of resistance, as well as crossbreeding and selection of offspring individuals.

Basal rot

First symptoms usually occur when head lettuce is approaching maturity. The fungus Rhizoctonia solani attacks the lower leaves in contact with the soil, causing ochre to brown lesions on the ribs. In humid weather, the infection can reach the entire limb, causing its destruction, or reach the taproot, causing crown rot. Hot and humid weather greatly favors the development of the disease. The fungus can easily survive in the soil for years. No resistant cultivars or fungicide are currently available.

Dry subsidence

The main agent causing this disease is the soil fungus Pythium sp. Characteristic symptoms include a lack of emergence, reduced plant growth (dwarfism), foliar yellowing, plant wilting, growth arrest and even death. Cold, damp and poorly drained soils are all aggravating factors. The fungus can survive for several years in the soil. Chemical control is inefficient and resistant varieties are still non-existent.

Telluric and bacterial diseases are particularly feared and their effects are very damaging. Our top priorities: research projects aimed at improving the knowledge of resistance and sensitivity factors of lettuce varieties and exploring the genetic diversity of lettuce to find sources of resistance to use in our plant selection program.

Lettuce aphid

The lettuce aphid Nasonovia ribisnigri (Mosley) is a pest responsible for major damage worldwide. This aphid has the peculiarity of colonizing and feeding in the heart of the head lettuce, where it is more difficult to detect and reach with contact insecticides, once the heads are developed. The mere presence of aphids inside the heads depreciates the quality of lettuce and makes them unsaleable.

In collaboration with Ontario's Vineland Research and Innovation Center (VRIC) and Rijk Zwaan (RZ) in Holland, we are developing lettuce lines resistant to the Nasonovia aphid through introgression of the Nr resistance gene and marker assisted selection. With this method, the development of new varieties is accelerated over time. Our resistant lines will be available by 2023. Resistant varieties are a real benefit for producers: less pesticides and respect for the environment.

Physiological disorders

Physiological disorders related to heat stress

Tip burn

Tip burn is characterized by necrosis on the ends and edges of young leaves in development. This disorder occurs mainly a few days before harvest and is attributed to localized calcium deficiency. Environmental conditions that promote rapid plant growth (warm temperatures, high light intensity and long photoperiod) or reduce transpiration (high relative humidity, low air movement, water stress) favor tip burning.

The presence of necrotic leaves in a lettuce affects its appearance and shelf life.

Rib discoloration

Symptoms develop when lettuce matures and becomes firmer. This physiological disorder is directly associated with heat stress. The onset of symptoms begins with small brown streaks along the midribs of the leaves beneath those surrounding the head lettuce. Ranging from light brown to black, the lesions darken over time and are often followed by rotting during storage, thus reducing lettuce quality and marketing.

Bolting

Also known as "going to seed", bolting is the rapid elongation of the main stem in the center of the plant, before the lettuce has reached an optimal weight for the market. The quality of the lettuce is thus strongly altered and no longer meets the marketing standards. This is especially true in romaine lettuce, where the length of the heart should not exceed one third of the plant's total size.

Bolting can result from several factors, including day length exceeding 13 hours of sunlight, as is the case in Quebec, the prevalence of high temperatures at particular stages of growth and certain stresses, such as lack of water.

Since they have no control over the weather in the fields, the selection of resistant varieties adapted to our conditions is a major asset for producers. Depending on the physiological disorder, crisphead lettuce varieties such as Hochelaga, Estival, AAC Champlain, AAC Canicula and AAC Richelieu have good tolerance levels and even resistance. Always in search of innovation, the Lettuce Foundation continues its research. Thus, new varieties of head and romaine lettuce should emerge in the coming years.