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TESTING FOR VIRUS IN REGISTERED SEED AND SCION ORCHARD BLOCKS IN WASHINGTON
Fifteen nurserymen voluntarily cooperate in the program today and produce the millions of certified trees, seeds and rootstocks grown in the state each year.
This stock is purchased and planted by orchardists and nurserymen throughout all of the fruit growing areas of North America.
Funds, which are provided by an industry self-imposed tax on stock grown and sold, have been adequate to support all program activities.
The most important program function is the establishment of nursery-owned, registered seed, scion and rootstock motherblocks.
The motherblock trees are propagated by the certifying agency using IR-2 virus-tested foundation material and are distributed to cooperating nurserymen for this purpose.
These registered blocks of trees are inspected and tested regularly for the virus and virus-like diseases common in the areas where they are established.
The primary virus problems encountered relate to the pollen-spread virus diseases of stone fruits.
These are the prune dwarf virus and the prunus ringspot virus strains which are common in commercial stone fruit orchards in Washington.
Only through thorough inspections, intensive testing and prompt removal of infected trees can clean virus-free motherblocks be maintained.