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PLANT QUARANTINES CAN FRUSTRATE GARDENERS

written by Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA This past week a local gardener called me. She was frustrated because the nurseries where she wanted to order a particular variety of rhubarb would not ship into Washington. She asked the nursery catalog folks about the reason and they explained that she wasn’t in the right ‘zone.’ Most gardeners would assume that they meant hardiness zone. However, that’s not the case. Throughout the U.S. there are a number of quarantines preventing the sale and transportation of plants from one area or zone to another. These quarantines are to prevent the spread of a particular insect, disease, or weed pest from one area of the country to a another. The quarantines may frustrate gardeners, but that’s not the intention. They’re actually there to protect us and our state’s agriculture. Let’s take a look at a few of the restrictions in Washington that may stymie area gardeners when mail ordering plants. JAPANESE BEETLE: I’m very familiar with this pest. I grew up and lived in New York state until I moved here in 1980. This beetle was a nightmare for me and most other gardeners and it continues to be a devastating pest of ornamental plants and turf in many eastern states. It’s larvae or grubs feed on grass roots, causing significant damage to lawns, pastures, and golf courses. The adult beetles are voracious feeders, eating the leaves, flowers, and fruit of hundreds of different types of ornamental plants and also agricultural crops. They generally eat all the leaf tissue between the veins, leaving behind a virtual leaf skeleton. The Japanese beetle is a foreign pest coming originally from Japan. It first appeared in the U.S. in 1916 in New Jersey. Since that time this beetle has spread throughout most of the states east of the Mississippi River. Although, it has also found its way west of the Mississippi into Arkansas, Iowa, Kansas, Minnesota, Missouri, and Oklahoma, many of these infestations have been eradicated before the beetle could become established. USDA is trying to restrain the artificial spread of the Japanese beetle with its quarantine. Nurserymen and sod producers who ship plants and sod out of Japanese beetle infested areas must have their materials inspected and certified free of the pest. Washington is one of the western states protected by this quarantine, in addition to Arizona, California, Idaho, Nevada, Oregon, and Utah. While the beetle is still spreading slowly westward on its own, the quarantine is helping protect the far western states. Some nurseries don’t want the added expense of having their stock inspected and certified, so they simply choose not to ship into the protected states. This greedy pest is difficult to control. It has built up resistance to many of the synthetic pesticides available to home gardeners. Attempts to control the Japanese beetle with biological agents have not been extremely successful. For quite a while, bacterial diseases were used to help control the beetle grubs in turf situations, but they’ve been losing efficacy over the years . Traps using Japanese beetle pheromones (insect hormones) as attractants can catch large numbers of adult beetles. However, researchers have found that these traps usually actually attract more adult beetles to an area, resulting in greater damage to area plants instead of less damage. ONION WHITE ROT: Do you like Walla Walla onions? So do a lot of other people. Onions are an important agricultural crop in Walla Walla county, as well as in Adams, Franklin and Grant counties. A devastating fungus disease called onion white rot (Sclerotium cepivorum) destroys onion crops and stays in the soil… preventing you from growing onions or its relatives for many years to come. This disease has already found its way into commercial fields in other Washington counties. In an attempt to keep it out of Adams, Franklin, and Grant counties the Washington State Department of Agriculture is restricting the movement of onions; onion relatives (garlic, leeks, chives, and shallots); tools and equipment used in onion and Allium (onion relatives) crops; soil from where onions were grown; and even livestock pastured on fields known to be infested with onion white rot. None of these items can be imported into these three counties unless the area they come from is a ‘white rot free area’ or they have been certified free of white rot. Do not plant uncertified onion plants or sets into your garden. Don’t share onions, garlic bulbs, or onion relatives with other gardeners. Don’t throw uncooked onion or garlic peelings into your compost pile. These are all ways you can unwittingly infest your own garden soil with onion white rot disease. These admonitions include ornamental onions or Allium. If you ignore the warnings and the quarantine, your soil could become infected and then you’ll never be able to grow onions or garlic again! Such is the case in many Yakima gardens where an old gardener shared his wonderful garlic with many other area gardeners. Unfortunately, his garlic was infested with white rot. Now, all the gardeners who were recipients of his largesse can’t grow garlic or onions in their gardens. OTHER QUARANTINES: Other quarantines that can frustrate gardeners include two quarantines on grape cuttings and plants. Grape plants shipped into Washington must be certified to be free of viruses and certified to be free of an insect pest called phylloxera that attacks the roots of grape plants. Both these pests have the potential of devastating the wine grape industry in our state. There are also several quarantines aimed at keeping diseased members of the genus Prunus (peaches, apricots, almonds, cherries, and plums) out of the state. Plants must be certified free of the diseases. Commercial fruit trees are included in these quarantines along with many ‘Prunus’ ornamentals, including myrobalan plum, cherry plum, “Atropurpurea,” purple leaf plum (Prunus cerasifera); wild goose plum (Prunus munsoniana); Japanese plum (Prunus salicina); hybrids of any of the above; and wild native species of plum. Fruit trees (Prunus) can be shipped into Washington if they are certified free of these diseases, but ornamental ‘Prunus,’ can’t be. If you try to mail order certain plants for your garden and the company tells you that they don’t ship into Washington, now you’ll know there’s a good reason…. plant quarantines. These quarantines are established to keep insect, disease, and weed pests from moving artificially from one area to another. Some gardeners have been known to try and bypass quarantines by bringing in uninspected or uncertified materials from out of state. Don’t. The quarantines are there to protect us, our gardens, and our local agriculture.

Published: 2/5/2005 2:00 PM

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