Articles from the November/December 2008 HortIdeas

Click on the highlighted titles to read full text.

  • “Extreme Genetic Engineering”: Farming's Future?
  • Dr. Marc Cathey, R.I.P.
  • 2009 Garden Calendars for the North and the South
  • American Garden Award Polling at Gardens in 2009
  • “Line Blaster” for Unblocking Drip Irrigation Systems
  • Seed-Propagated Lowbush Blueberry Cultivars
  • On Fertilizing Herbaceous Perennials in the Southeast
  • An Extremely Simple Solar Food Dryer
  • Online “Backyard Composting Basics” Course
  • Straw Mulch vs. Onion Thrips
  • Effects of Onion Set Size on Bolting and Bulb Yields
  • Rose Cultivars Evaluated in Texas with “Minimal Inputs”
  • Update on Mistletoes
  • Phellodendron Bark Extracts versus Brown Rot of Peach
  • “Vegan” Gardening Gloves
  • Managing Weeds in Large Pots Using Pine Bark Mini-nuggets
  • Yellowing of Japanese Holly Fern Foliage is Due to a Virus
  • “Easy” Vermicomposting
  • The Greenprint Initiative
  • Research on Using Predator Boxes for Pest Management
  • How Fast Does Dieback Due to Emerald Ash Borer Spread?
  • Sea Buckthorn Yield Trials
  • High-Temperature Drying Cuts Kale and Spinach Carotenoids
  • New Urban Agriculture Alliance
  • A Thread to Black Walnut Trees in the West (and the East?)
  • “Largest Selection of Plants from Australian Seed Sources”
  • A Case Study: Moving to More Sustainable Ag Methods
  • Composting Can Reduce Greenhouse Gas Emissions
  • Plant-Pathogenic Bacteria as Potential Bioweapons?
  • Book Review: Planthropology: The Myths, Mysteries, and Miracles of My Garden Favorites, by Ken Druse
  • Book Review: The Complete Book of Garlic: A Guide for Gardeners, Growers, and Serious Cooks, by Ted Jordan Meredith
  • Book Review: Medicinal Spices: A Handbook of Culinary Herbs, Spices, Spice Mixtures and Their Essential Oils, by Eberhard Teuscher
  • DVD Review: Proper Methods for Pruning Grapevines (2-DVD Set), by Lon J. Rombough
  • The PrestoPlanter
  • Compost Comfort® Compost Bags
  • Praise for the Oasis Automatic Indoor Plant Waterer
  • Tubtrugs(R)
  • PredaLure(R) Attracts Beneficials
  • OnLine: The Human Flower Project
  • Reduce Mowing Frequency to Cut Your Lawn's CO2 Output
  • Crapemyrtle Pruning Methods Compared
  • Overwintering Survival of Multicolored Asian Lady Beetles
  • A&UF Special Issue on “Assessing Urban Forest Structure”
  • OnLine Publication on Fire and Nonnative Invasive Plants
  • Squash and Gourd Bees Are “Good News” for Growers
  • Lots of Phytoestrogens in Pumpkin Seeds
  • “Composting Is the Best Bang for the Buck” ...
  • Flawed Produce Is No Longer Illegal in EU Groceries
  • World Wildlife Fund's Living Planet Report 2008
  • Book Review: The Informed Gardener, by Linda Chalker-Scott

Straw Mulch vs. Onion Thrips

Entomologists at the New York State Agricultural Experiment Station report that shredded wheat straw applied as a mulch (at a rate of 3.5 pounds per 100 square feet) resulted in lower densities of onion thrips (Thrips tabaci) in commercial onion fields in western New York. The fields received no insecticides during the experiment. In laboratory trials, straw mulch was found to interfere with the development of onion thrips, resulting in greatly reduced adult emergence from container-grown onion seedlings that had been inoculated with immature thrips.

The entomologists conclude: “Both conventional and organic farmers should consider the use of straw mulch for T. tabaci.”

Reference: E. Larentzaki, J. Plate, B. A. Nault, and A. M. Shelton (Dept.of Entomology, New York State Agricultural Experiment Station, Cornell University, 630 W. North St., Geneva, NY 14456), “Impact of Straw Mulch on Populations of Onion Thrips (Thysanoptera: Thripidae) in Onion,” Journal of Economic Entomology 101(4), August 2008, 1317-1324. (Entomological Society of America, 9301 Annapolis Rd., Lanham, MD 20706.)

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A Threat to Black Walnut Trees in the West (and the East?)

Colorado State University plant pathologist Ned Tisserat has published overviews of what he terms “walnut decline” at the web site—ominous overviews, in our opinion.

As related by Dr.Tisserat, the history of walnut decline begins in 2003, when rapid decline and death (sometimes in less than a year) was first seen among the black walnut (Juglans nigra) trees planted as ornamentals in and around Boulder, Colorado. Most Boulder-area black walnuts were dead by the fall of 2007. Deaths of black walnut trees have also been reported in other areas of Colorado.

The walnut twig beetle (Pityophthorus juglandis), native to the southwestern U.S., has been “consistently found in declining trees” in Colorado, and in the fall of 2007, a particular fungus (genus Geosmithia) was found to be associated with the beetle. In trials conducted this year, when black walnut seedlings were inoculated with the fungus, cankers appeared on the seedlings within three weeks.

Black walnut dieback correlated with walnut twig beetle infestations has also been documented in New Mexico, Oregon, and Utah. Dr.Tisserat writes: “We are not aware of any reports of black walnut decline in its native range [which does not include the West], but certainly we should increase surveillance throughout the eastern United States and the English walnut [J. regia] production areas of California to insure that this pest complex has not been introduced.”

For updates on walnut decline (also known as “thousand cankers disease”), see the Phytosanitary Alert System’s web site at

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Compost Comfort® Compost Bags

To us, this is one of those “why didn’t I think of it?” ideas that makes a lot of sense: put materials for composting in durable fabric bags that are permeable to both air and water! It could make handling compost much less messy at all stages, from gathering the materials to applying finished compost to garden beds. Perhaps most significant, compost is extremely easy to “turn” by just flipping and shaking its bag. And, when needed, water can be added through the bag.

There are two sizes of Compost Comfort® bags available: 9 gallons (1.13 bushels) and 18 gallons (2.25 bushels). For a large compost pile, you can pile up several bags. The bag fabric is Coolaroo® outdoor “knitted shadecloth” with a 10-year warranty against ultraviolet damage. Special long-life TENARA® thread is used for all sewing. The bags are made in Arkansas.

To learn more, call Less Work Gardening Inc. at 410-781-8856 or visit As of late November 2008, online ordering at the web site was “under construction.”

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Reduce Mowing Frequency to Cut Your Lawn’s CO2 Output

Based on trials conducted in Canada, one way to reduce carbon dioxide emissions from turfgrass is to mow less often. Mowing turfgrass plots (mainly Kentucky bluegrass, annual blue grass, and red fescue, with considerable clover and various weeds in some cases) every week during the growing season resulted in up to four times as much carbon dioxide emissions annually as mowing only three or fewer times during the growing season. In fact, the Canadian researchers measured annual emissions of about 0.4 pounds of carbon dioxide per square foot of frequently mowed turfgrass. That might not sound like much, but the area of turfgrass in the U.S.alone is around 50 million acres (roughly triple the acreage of irrigated crops), with total annual carbon dioxide emissions possibly as much as around 900,000,000,000 pounds if mowed frequently versus only around 220,000,000,000 pounds if mowed infrequently.

If your lawn has an area of 2,000 square feet, reducing mowing frequency might cut its annual carbon dioxide emissions by as much as 600 pounds. Since carbon dioxide emissions resulting from burning a gallon of gasoline amount to nearly 20 pounds, the annual reduction in emissions due to less-frequent mowing is similar to the reduction in emissions due to cutting back driving of a gasoline-fueled vehicle that averages about 20 miles per gallon by 600 miles.

Reference: S. E. Allaire (Centre de Recherche en Horticulture, Université Laval, Quebec, CANADA G1K 7P4), C. Dufour-L’Arrivée, J. A. Lafond, R. Lalancette, and J. Brodeur, “Carbon Dioxide Emissions by Urban Turfgrass Areas,” Canadian Journal of Soil Science 88(4), August 2008, 529-532. (Agricultural Institute of Canada, Suite 1112, 141 Laurier Ave. W., Ottawa, Ontario, CANADA K1P 5J3.)

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