   2002 Wildfire Season - June 5, 2002 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County As I write this column on May 30, 2002, I am reflecting on our current wildfire risk. Right now, the Bullock Fire is burning in the Catalina Mountains north of Tucson and has impacted 20,800 acres. Mt. Lemmon has been evacuated and that fire still threatens homes and communications equipment. Earlier in May, five home were lost to the Indian Fire in Prescott. This fire burned about 1,300 acres and has prompted many citizens to take action to reduce wildfire risk around homes and landscapes. Cooperative Extension continues to handle these calls and answer landscaping and fuel reduction questions. Some of the non-gardening questions I have been asked refer to weather forecasts, fuel treatments, and fire retardants. These are addressed below. Monsoon season is still more than a month away and, depending on whom you believe, it is expected to bring below average rainfall. The long range forecast also indicates above normal temperature can be expected through October 2002. There is some good news: El Nino conditions are building in the Pacific and it appears that we may see above average precipitation next winter. If this trend continues, it will likely be a weak to moderate El Nino rather as opposed to the strong effects experienced in 1997-98. This may help us out next year, but, for now, we are still facing drought conditions. Folks living in the wildland/urban interface (residential areas adjacent to wildlands or open space) should consider reducing fuels around their homes and assessing other parameters such as access for firefighters, flammability of existing landscape plants, roofing materials, etc. Earlier this year (February 20, 27, and March 6), I wrote a series of three articles on firewise landscaping and creating defensible space. These are available on the Backyard Gardener web site or by request from Yavapai County Cooperative Extension offices (contact information is at the end of the column). The news media has been showing lots of images of planes dropping fire retardant during firefighting efforts. Have you ever wondered what the red slurry material is made of? There are several types, but many have ingredients in common. In general, they are mixtures of diammonium sulphate, diammonium phosphate, monoammonium phosphate, gum thickeners, iron oxide as a coloring agent, and preservatives to prevent spoilage. As you can see, the first three ingredients are also considered fertilizers. These materials are shipped in bags, which are mixed with water and pumped into tanks in fixed wing aircraft. The retardant slurry is dropped from planes onto fuels in or near the fire. The slurry forms a combustion barrier after the evaporation of the water carrier, and their effectiveness depends on the amount of retardant per unit surface area. The retardant remains effective until it is removed by rain or erosion. The ammonium salts chemically combine with cellulose as the fuels are heated effectively preventing the treated fuels from igniting. Coloring agents are usually omitted when firefighting in wilderness areas. Short-term fire retardant materials are also used in firefighting efforts. These are typically applied to structures and adjacent fuels by ground-based pumper trucks. Unlike the long-term retardants, which remain effective after the water has evaporated, short-term fire retardants depend on the water they contain to retard or suppress the fire. These materials contain water, surfactants, foaming, and wetting agents. The foaming agents affect the rate at which water drains from the foam, and how well it adheres to the fuel. The surfactants and wetting agents increase the ability of the drained water to penetrate fuels thus reducing their ability to ignite. Fuels are insulated from heat, and air contact is also reduced. These retardants lose their effectiveness once the water has evaporated or drained from them. We have a variety of tools available to us to minimize our wildfire risk. Unfortunately, fires will likely continue to burn across the west this season. Arizona's National Forest and State Trust Land closures should help, but I fear we should expect more fires and be ready for them. Are you prepared? The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/. |