March, 1998

Check-off for apple rootstock research comes to fruition

By Jeremy Compton and Win Cowgill
Rutgers University

At the 41st annual meeting of the International Dwarf Fruit Tree Association in Pasco, Wash. this past month, tree fruit nurserymen from around the world hosted an open forum of growers, researchers and Extension personnel.
The topic was setting priorities for apple rootstock research and obtaining adequate funding. The IDFTA, one of the most prominent fruit growing organizations in the world, has long supported rootstock research through its Rootstock Research Foundation. Through the efforts of Bruce Barritt, Washington State University researcher and educational director for the IDFTA, the idea of a checkoff on nursery liners has become a reality. Funds generated will be distributed through the IDFTA.
A charge of one-half cent per liner sold will be assessed to nurseries for use in apple rootstock research, beginning in 1998. This assessment is being used only on apples and is expected to raise around $90,000 per year to aid research. The pilot program will be evaluated only for apples in 1998. If this program proves to be a success, the possibility for expansion into other commodities, such as pears, cherries, and peaches will be evaluated in the future. This assessment on rootstock liners will allow researchers to focus on the issues of concern to develop rootstocks for the future.
The forum gave everyone an opportunity to discuss concerns regarding currently available rootstocks, and research that will most benefit the industry. Among the top points of focus were the lack of disease tolerance, productivity and the inability to root in the nursery of some of the current, more widely accepted rootstocks.
Ron Perry of Michigan State University explained how the NC-140 rootstock trials are a good way to answer a lot of pressing questions quickly.
"It is necessary to evaluate new rootstocks in these trials before they are released commercially. These trials expose the rootstocks to a wide variety of soils and climates while allowing the researcher to make the mistakes, instead of the commercial grower" explained Perry. "The only limiting factor is funding."
The beginning focus of this new assessment will be to re-evaluate some of the existing rootstocks that have been thrown out of quarantine and breeding programs. As Washington state grower George Ing concluded "We may already have the answers to our problems, let's evaluate what we have before the production of more material."
Greg Lang of WSU added "There have been thousands of rootstocks tossed out of USDA quarantine due to the lack of money to evaluate them."
When a rootstock comes into the country, it first has to go through a USDA quarantine lab in either Prosser, Wash. or Beltsville, Md. If a rootstock is clean of virus it will take $100 to $200 to get it through quarantine. If the rootstock needs to be cleaned up, it can take up to $1,500 before it is ready to move out for field testing. This expense has caused a lot of potential material to be tossed out in the past without being thoroughly evaluated.
Currently there are only six tree fruit breeding programs in the United States. Only the Cornell program at Geneva is doing work on apple rootstocks. Geneva is focusing its efforts on breeding rootstocks mainly for fireblight resistance. Terence Robinson of Cornell gave a report on the Geneva breeding program's progress and what potential stocks they have coming down the pipeline. The release of G30 was made over the past year. Robinson reported "G30 is a fireblight resistant stock that is between M7 and M26 in size. It is proving itself to have better yield efficiency than either M7 or M26 and has looked good in trials so far. G30's drawbacks are that it is showing a brittle graft union on some of the newer varieties and is a tough stock for the nurseries to manage." G30 is currently on test in the NC-140 1994 planting in locations throughout North America.
He also indicated another advanced selection, G16, is being released for second test evaluation in 1998. G16 produces an M9 type tree that is resistant to fireblight.
The need for new rootstocks becomes increasingly important as production requirements and restrictions become more demanding. We will require a rootstock that allows us to manipulate the tree, with minimum inputs, if we are to meet our needs and prosper in the future.
The Virtual Orchard World Wide Web site hosts a web page for the IDFTA at http://orchard.uvm.edu/IDFTA/.
For additional information on the IDFTA or on rootstock research visit the Virtual Orchard at http://orchard.uvm.edu/.