Apr 7, 2007

Asparagus Expert: Disease Resistance Needed

Asparagus growers in Michigan aren’t the only ones who face challenges. New Zealand growers deal with many of the same issues, including competition, disease, funding and privatization.

Michigan growers got an international asparagus perspective from Peter Falloon during the 2005 Oceana Asparagus Day March 10 in Shelby, Mich. Falloon is a horticultural consultant and the director of Aspara Pacific, an asparagus grower, supplier and research laboratory in Christchurch, New Zealand.

New Zealand used to be the largest producer of green asparagus in the Southern Hemisphere, but the industry is in decline and is now ranked fourth or fifth. The island nation is better known for dairy farming nowadays, as well as tourism, thanks to the success of “The Lord of the Rings” movies, Falloon said.

Aspara Pacific used to be a public entity, but was recently converted to a private company. Falloon said it’s a “cradle to grave” operation that works in every area of asparagus production: breeding, seeding, researching, growing, packing and exporting. There are about 60 employees, many who work seasonally. Most of the asparagus is exported to Japan.

“The New Zealand asparagus industry has the highest number of scientists per hectare in the world,” he said. “That either means we’ve got too few hectares or too many scientists.”

Falloon is chairman of the New Zealand Asparagus Council. Despite the asparagus industry’s recent privatization, the national government still has a strong presence. For every $100,000 the council puts into research, the government puts in $1 million, Falloon said.

New Zealand asparagus is primarily a processing industry. It’s facing increased competition from processed asparagus in China and Peru. Falloon has toured Chinese asparagus facilities and is familiar with some of their strengths and weaknesses.

Chinese companies grow asparagus on 185,000 acres, using virtually no herbicides. It’s mostly organic. Human effluent is used to fertilize crops. Little refrigeration is used in storage, due to a lack of electricity. When added together, those factors make for cheap asparagus, but the quality isn’t always there, Falloon said.

Aspara Pacific works with a variety of asparagus. The company has recently been growing purple asparagus, which tastes sweeter than the green variety but has less fiber, Falloon said.

Disease is always a concern. Lately, New Zealand growers have been worried about asparagus rust in Australia, which has spread throughout the larger country’s main production areas. Asparagus rust has yet to appear in New Zealand, but growers there fear it’s only a matter of time before west winds spread the disease to their islands. As a result, they are already making preparations, Falloon said.

New Zealand deals with another disease Michigan growers are familiar with: phytophthora rot. Falloon has spent years studying phytophthora, and he shared some of the lessons he’s learned with his audience at the asparagus conference.

“Under cool, wet conditions, phytophthora rot can reduce asparagus yields by 50 percent,” he said.

The trick to controlling phytophthora is controlling it in the field. Phytophthora thrives in wet conditions, but it can survive in warm conditions, where it lies dormant. Seemingly healthy spears can be infected with the disease. When they start to rot, they take on a slimy, disgusting appearance. The rot appears at soil level or just above. Growers who only look at spears on the surface don’t always see the rot, and tend to underestimate the disease, he said.

To avoid crop losses, growers should strive to breed disease-resistant varieties of asparagus. Breeding should be done in a nursery or greenhouse and not in the main production fields. Also, equipment used in the nursery should not be used in production fields, Falloon said.

Ridomil is the most effective chemical to use on phytophthora. However, Ridomil is not cheap. It should be used in the wet season, but using it during the dry season would be a waste of money.

“The drop off in disease severity is dramatic in the summer,” Falloon said.