Improving post-harvest quality tops the lettuce industry's priority list, according a recent direct mail survey completed by Asgrow Vegetable Seeds, a leading developer of new lettuce varieties.

Results show that 90% of respondents, which included growers and shippers in Arizona and the Salinas and Imperial valleys, said that overall head and leaf attractiveness is 'essential' or 'very important' in developing new varieties. Moreover, 84% 'agreed' or 'strongly agreed' that the lettuce
industry needs to focus more on end-user and fresh-cut needs.

This is good news to Asgrow, which launched a new line of lettuce varieties last year. Dubbed Aussie Lettuce by the industry, the new varieties developed by renowned Australian plant breeder Dan Trimboli combine beauty with strong disease resistance. 

While most lettuce breeding programs access the same germplasm (the building blocks of new varieties), Trimboli is putting a different accent on his program, so to speak. "Because we are in isolation here [in Australia] we tend to be working with different genes," he said during a radio interview on KRKC in Monterey County, California. "We believe that the tougher conditions here produce a slightly different style of lettuce compared to what they [breeders] are doing in California; only slightly, but it can make a big difference."

"We're very much market driven; it's what the market wants that matters," said Trimboli, who broke into the American seed business 20 years ago with some of the first disease-resistant lettuce. "You must breed close to the specifications of growers and shippers, but you must also have a novel aspect to your breeding; something that is new - something that they might not have seen before." 

According to Trimboli, once potential varieties are identified in Australia, the final selection work and slotting is done in actual production fields of California and Arizona. This ensures local suitability.

CORKY ROOT A GROWING PROBLEM
Other survey results showed that over half of respondents have a problem with corky root, a soilborne bacterium, on their ranch - more than originally thought by Asgrow. Still over 40% did not know how this persistent disease affects the growth of the plant.

Trimboli, who is a trained pathologist, explained that corky root reduces seedling vigor and the ultimate size potential of a variety; it can also affect earliness. The best control, he believes, is using a resistant variety. "We have virtually the same line with and without corky root resistance, and I have been staggered to see the difference between resistant and non-resistant varieties," said Trimboli. "Corky root does an awful lot of damage to romaines." He pointed out that Outback, a corky root resistant romaine from Asgrow, has outyielded non-resistant lines in infected fields, showing better box weight potential, and plant height.

According to the survey, the most problematic diseases for lettuce operations remain downy mildew, with 86% saying its damages their crop, followed by 81% who say that big vein can limit their product quality and yields.

AUSSIE TRIAL RESULTS
Outback continues to be Asgrow's top new Aussie romaine, according to Kristie Vanoli, an Asgrow sales rep in the Salinas Valley. The tall vigorous plant carries weight well into the base with a sufficient leaf-to petiole-ratio for fresh-processed salad, heart and carton packs. "It's typically very uniform, and is one of the earliest maturing romaines in its class," she said. 

Two pre-commercial varieties with strong disease resistance are gaining attention as well, reported Juan Pablo Arce, Asgrow product development specialist. The first is XP 9200-138, a romaine primarily suited for heart production. "It is best suited for cooler season desert and coastal California production areas," he noted. It is resistant to corky root rot and downy mildew races 1-12. An up-and-coming iceberg, EX 9200-027 is a consistently performing main season iceberg lettuce for warmer coastal California growing seasons and areas. "It has very good cap leaf development with good head holding ability," Arce noted. It is corky root resistant as well.

Company news release
N2767