The Clean Plant Center Northwest uses several old homemade growth chambers for heat therapy of virus-infected plants at the Washington State University Irrigated Agriculture Research and Extension Center in Prosser, Washington. Using fees collected from the sale of WA 38 graft wood, the Northwest Nursery Improvement Institute has donated the funds for a new chamber at the center.(TJ Mullinax/Good Fruit Grower)
The Clean Plant Center Northwest uses several old homemade growth chambers for heat therapy of virus-infected plants at the Washington State University Irrigated Agriculture Research and Extension Center in Prosser, Washington. Using fees collected from the sale of WA 38 graft wood, the Northwest Nursery Improvement Institute has donated the funds for a new chamber at the center. (TJ Mullinax/Good Fruit Grower)

The coalition of nurseries providing the trees for Washington’s WA 38 apple tree plantings has donated a critical piece of equipment to the Clean Plant Center Northwest in Prosser, Washington.

Using fees collected from growers for graft wood and budwood, the Northwest Nursery Improvement Institute has given $50,000 to the Clean Plant Center to purchase a new growth chamber used to eliminate viruses in plant material.

The new chamber, sometimes called a heat chamber, is a more efficient commercial model than the homemade versions currently used at the center, said Scott Harper, director of the Clean Plant Center. It features more control over temperature, humidity and light.

“We’ll get much more control over the process,” Harper said.

Clean Plant Center Northwest Director Scott Harper said the new growth chamber is a more efficient commercial model than the homemade versions currently in use and will provide more control over temperature, humidity and light. (TJ Mullinax/Good Fruit Grower)
Clean Plant Center Northwest Director Scott Harper said the new growth chamber is a more efficient commercial model than the homemade versions currently in use and will provide more control over temperature, humidity and light. (TJ Mullinax/Good Fruit Grower)

The new unit will also be about twice the size of the current chambers, roughly the size of a kitchen refrigerator, increasing the center’s capacity at a bottleneck point in the overall regimen of ensuring that the tree fruit orchards and grape vineyards remain virus-free. Plants spend up to three months inside the chambers, so the center has quite a backlog, Harper said.

The Northwest Nursery Improvement Institute donated the $50,000 in December, though Harper expected it to take months to order the chamber and get it up and running.

The institute, also based in Prosser, is a network of nurseries contracted to provide the trees, graft wood and budwood for the state’s commercial plantings of WA 38, or Cosmic Crisp, the new apple bred at Washington State University.

WSU collects a $1 royalty for every Cosmic Crisp tree sold. However, the nurseries make more profit when selling a finished tree on its own roots compared to selling graft wood that orchardists use to topwork exiting trees, or budwood that orchardists use to build their own nursery trees or have them built outside the Nursery Improvement Institute, and are therefore in a better position to contribute to research and other forms of industry support, said Bill Howell, manager of the institute.

To make up for that, the institute charges an additional 25-cent industry support fee for each tree a grower produces by topworking or budding outside the institute nurseries. Since sales of Cosmic Crisp trees started, the group has collected about $45,000 from the fee, which it has given to the Clean Plant Center along with another $5,000 from its budget, Howell said. •

—by Ross Courtney