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Gardening in Washington State

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Does Buffalograss Grow Well in Washington State?

To determine if buffalograss is a suitable turfgrass for central Washington, Dr. Gwen Stahnke, Extension Turfgrass Specialist for WSU, established the first set of test plots at the Yakima Area Arboretum in Yakima, Washington, over 15 years ago. Plots were also established in Pullman, Washington, but these did not survive, probably because of drying out over the winter. The loss of buffalograss in Pullman may have been due to winter desiccation. Because of the low soil temperatures for much of the year in western Washington, buffalograss is not recommended for planting there, since it is quickly outcompeted by cool-season grasses and weeds. To summarize regarding adaptability, buffalograsses are only suited for use in low- to moderately-maintained areas in central Washington.


For more information, a free downloadable PDF is located here Buffalograss for Use In Central Washington FS 095E

Submitted by: Marianne Ophardt,  May 19, 2015


Organic fungicides

Plant diseases caused by fungal pathogens are very common in home gardens in the Pacific Northwest, particularly west of the Cascade Mountains. Spring rains combine with warm temperatures and tender new plant growth to create ideal conditions for fungi to thrive and spread. Common fungal diseases seen in home gardens include powdery mildew, downy mildews, rusts, and late blight. Fortunately, there are many products available to home gardeners for managing diseases caused by fungal pathogens on plants. This fact sheet describes organic fungicides and provides information on:
• which organic fungicides are legal and available to home gardeners,
• how effective these organic fungicides are, and
• whether the products have unintended effects on people or the surrounding environment

Copper sulfate

More information is available on this free, downloadable fact sheet:

Submitted by: Linda Chalker-Scott, May 15, 2015

A Beneficial Wasp in the Wrong Place, Wrong Time Becomes a Pest

As a newcomer to our home landscapes in the Pacific Northwest (PNW), the European paper wasp, Polistes dominula, has a reputation as both a beneficial predator and a pest. The European paper wasp is a relatively tame wasp that forages within landscape plants in search of leaf-feeding caterpillars and other insect prey. However, it is also a nuisance pest that will sting people who accidentally disturb or threaten it or its nest.

Paper wasp

In early spring, homeowners may remove wasp nests by knocking them down with a long broom, pole, or strong stream of water from a hose. This is the best time to remove a nest because only a single female will be guarding it. It may take repeated removal of each nest to discourage the wasps from replacing it. It is important to wear gloves and protective clothing to reduce any risk of getting stung, and although the sting is mild, it will get your attention.

For more information, go to The European Paper Wasp  FS152E located at

Submitted by: Mike Bush and Todd Murray, March 31, 2015


References for rubber mulch fact sheet

Arthur, M.A. and Y.T. Wang. 1999. Soil nutrients and microbial biomass following weed-control treatments in a Christmas tree plantation. Soil Science Society of America Journal, 63(3):629-637.

Azizian, M.F., P.O. Nelson, P. Thayumanavan and K.J. Williamson. 2001. Environmental impact of crumb rubber asphalt concrete leachate contaminants from highway construction and repair materials on surface and ground waters. American Chemical Society Abstracts 221(1-2): ENVR 15.

Bush, E., A. Owings and K. Leader, K. 2003. Foliar accumulation of zinc in tree species grown in hardwood bark media amended with crumb rubber. Journal of Plant Nutrition 26(7):1413-1425.

Bush, E., K. Leader and A. Owings. 2001. Foliar accumulation of zinc in tree species grown in pine bark media amended with crumb rubber. Journal of Plant Nutrition 24(3): 503-510.

Calkins, J.B., B.T. Swanson and D.L. Newman. 1996. Weed control strategies for field grown herbaceous perennials. Journal of Environmental Horticulture 14(4):221-227.

Chalker-Scott, L. 2007. Impact of mulches on landscape plants and the environment – a review. Journal of Environmental Horticulture 25(4): 239-249.

Christiansson, M., B. Stenberg and O. Holst. 2000. Toxic additives: A problem for microbial waste rubber desulphurization. Resource and Environmental Biotechnology 3(1): 11-21.

Ginsberg, G., B. Toal and T. Kurland. 2011. Benzothiazole toxicity assessment in support of synthetic turf field human health risk assessment. Journal of Toxicology and Environmental Health Part A 74(17):1175-1183.

Gualtieri, M., M. Milani, M. Camatini, M. Andrioletti and C. Vismara. 2005. Toxicity of tire debris leachates. Environment International 31(5): 723-730.

Kanematsu, M., A. Hayashi, M.S. Denison and T.M. Young. 2009. Characterization and potential environmental risks of leachate from shredded rubber mulches. Chemosphere 76(7):952-958.

Li,X.L., W. Berger, C. Musante and M.I. Mattina. 2010. Characterization of substances released from crumb rubber material used on artificial turf fields. Chemosphere 80(3):279-285.

Llompart, M., L. Sanchez-Prado, J. Pablo Lamas, C. Garcia-Jares, E. Roca and T. Dagnac. 2013. Hazardous organic chemicals in rubber recycled tire playgrounds and pavers. Chemosphere 90(2):423-31.

Ruffino, B., S. Fiore and M.C. Zanetti. 2013. Environmental-sanitary risk analysis procedure applied to artificial turf sports fields. Environmental Science and Pollution Research 20(7):4980-4992.

San-Miguel, G., G.D. Fowler and C.J. Sollars. 2002. The leaching of inorganic species from activated carbons produced from waste tyre rubber. Water Research 36(8): 1939-1946.

Simcox, N.J., A. Bracker, G. Ginsberg, B. Toal, B.Golembiewski, T. Kurland and C. Hedman. 2011. Synthetic turf field investigation in Connecticut. Journal of Toxicology and Environmental Health Part A 74(17):1133-1149.

Smolders, E. and F. Degryse. 2002. Fate and effect of zinc from tire debris in soil. Environmental Science and Technology 36(17): 3706-3710.

Snoddy, E.T. and A.G. Appel. 2013. Mulch preferences of the Asian cockroach (Dictyoptera: Blattellidae). Journal of Economic Entomology 106(1):322-328.

Solano, L., A.G. Ristvey, J.D. Lea-Cox and S.M. Cohan. 2012. Sequestering zinc from recycled crumb rubber in extensive green roof media. Ecological Engineering 47:284-290.

Steward, L.G., T.D Sydnor and B. Bishop. 2003. The ease of ignition of 13 landscape mulches. Journal of Arboriculture 29(6): 317-321.

Stokes, V. 2012. Some biodegradable mulch materials provide effective weed control during establishment of ash (Fraxinus excelsior L.) on farm woodland sites. Quarterly Journal of Forestry 106(4): 257-268.

U.S. Environmental Protection Agency (EPA). 2014. Common Wastes & Materials-Scrap Tires-Basic information.

Wik, A. and G. Dave. 2005. Environmental labeling of car tires – toxicity to Daphnia magna can be used as a screening method. Chemosphere 58(5): 645-651.


Acetic acid/vinegar as pesticide ingredients

Acetic acid is one of the few chemicals with two common names. Both depend upon its concentration. “Vinegar” means concentrations up to 8%. “Acetic acid” means concentrations higher than 8%. When the concentration is low enough to be called vinegar, it is a food product. When the concentration is high enough to be called acetic acid, and it is used to kill weeds, it is a pesticide. The point to remember with acetic acid is that high concentrations are more effective on woody perennial weeds, while low concentrations will work effectively only on very young weed seedlings.


For more information on using acetic acid/vinegar as a pesticide, see WSU FS161E.

Submitted by: Catherine Daniels, March 9, 2015


Organic Soil Amendments in Yards and Gardens: How Much is Enough?

Gardeners apply organic soil amendments to improve soil and raise healthy plants. While organic soil amend­ments benefit most garden soils, over-application can waste money, increase the risk of harm to water quality, and in some cases, harm plants.


Apply about 1/2 inch of organic soil amendment to an established garden bed. Photo by Mary Cogger.

For new garden or landscape plantings, add 1 to 3 inches of organic soil amendment to the soil and incorporate to a depth of at least 6 to 8 inches. If your soil lacks organic matter (typically light colored with poor physical proper­ties), add 2 or 3 inches of amendment. If your soil has adequate organic matter, or if salts are a concern, add less (or none at all).

If you are establishing landscape plants, amend the entire bed, and not just the planting holes. Permanent landscape beds don’t need organic soil amendments after the ini­tial application. Decomposition of leaf litter and organic surface mulches will help maintain organic matter, creating an environment similar to soil found in forests. Established gardens and landscapes require less organic soil amend­ments—typically about ½ inch per year.

For information on organic amendments in your garden and landscape, see the WSU fact sheet

Submitted by: Paula Dinius, February 16, 2015


Backyard Cherries without the Cherry Maggots

Before planting a backyard cherry tree, homeowners should consider the challenge of pest management, especially management of the western cherry fruit fly (WCFF).

Fruit infested with the cherry fruit fly larvae, known as maggots, may have a dimpled appearance, but the maggots can still be difficult to detect when examining the surface of the fruit. However, as the maggots mature, they break the surface of the cherry and open a hole in order to breathe and exit the fruit.

cherry maggot
Sweet cherry infested with cherry maggot.  Photo by Mike Bush, WSU Extension.

There are relatively few proven strategies that homeowners can use to manage this pest. The primary non-chemical strategy to manage WCFF is to pick off every cherry from the tree at harvest. WCFF management will be considerably easier for homeowners who plant fruit trees grafted to dwarfing rootstocks. For a list of pesticides (including organic products), homeowners can access the WSU Hortsense website at .

Pruned cherry
Backyard sweet cherry skillfully and properly trained/pruned to a 10-foot height.  Photo by Fred Staloch, WSU Master Gardener volunteer.

For more information on organic management of tree fruit pests see the WSU Extension manual FS125E- The Western Cherry Fruit Fly and Your Backyard Cherry Tree by Michael Bush and Marianne Ophardt on-line at

Submitted by: Mike Bush, February 9, 2015

The Correct Way to Use Pruning Tools

Using the right pruning tool for the job and using it correctly is safer for the gardener and produces cleaner cuts on the plant. When using cutting tools, it is important not to twist or strain the blades.

Do not cut with the tip of the blade; instead, set the branch to be cut as deep in the jaws of the pruners as possible to make a clean cut. If only a portion of the blade is used to make a cut (such as the tip), it may result in an incomplete cut.

If there is any strain while trying to make a cut with a sharp blade, switch to a larger tool. Trying to cut a large a branch with a tool that is too small may result in a jagged wound that damages the plant and may ruin the tool. Poor quality cuts may also result from twisting, pulling, or turning the tool while cutting. Use sharp scissors or a pruning knife to trim any tears or rough edges that result from a poor cut.

Incorrect    Correct

Incorrect:  branch too large for tool                             Correct:  Tool correct size for cut

For more information on pruning tools, go to Pruning Equipment for Home Gardeners.

Submitted by: Tim Kohlhauff, February 2, 2015


Dwarf Rootstocks for the Home Orchardist

Home gardeners should consider using fruit trees grafted to dwarfing rootstocks. Trees grafted on dwarfing rootstocks are not only shorter, but take up far less space within the home landscape. They also tend to mature and set fruit sooner than full-sized trees. Fruit trees grafted on dwarfing rootstocks are easier for homeowners to maintain and manage pests by organic means. Dwarfing rootstocks for apple, cherry, pear, prune, and plum are available to home­owners at many home and garden centers. Some nurseries sell just the rootstocks for home gardeners who are interested in budding or grafting their own dwarfing fruit trees.

Dwarf appleTraditionally, apple trees in western Washington have been sold on semi-dwarfing rootstocks. Depending upon the vigor of the cultivar, it is not uncommon to find trees reaching a height of over 15 to 18 feet when semi-dwarf rootstocks are used. To best ensure that the total tree height will not exceed 10 feet, homeowners should select trees with fully dwarfing rootstocks such as M9, Bud 9, or M27 varieties. Full dwarfing rootstock trees are now available at independent garden centers.

The fruit on dwarf rootstock trees should be compa­rable in size to those found on semi-dwarf rootstocks. Full dwarfing rootstocks trees are not self-supporting. They require support either from a post or a wire trellis. Trees grown on full dwarf rootstocks typically bear fruit within 2 years, while trees on semi-dwarfing rootstocks may take 4 to 5 years.

Regardless of the rootstock chosen, overall tree size is best maintained by proper training and pruning.

For more information, see Organic Pest and Disease Management in Home Fruit Trees and Berry Bushes .

Submitted by Charles A. Brun, January 20, 2015


Vegetable grafting workshop – February 2015

Vegetable grafting workshop offered in February: Grafting 2015

The on-line registration address is

tom in clip


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