Mulch Ado About Nothing
Snopes urban legends reference page
Here's the Cornell Cooperative Extension Community Horticulture response from Lori Bushway, Senior Extension Associate, Department of Horticulture and Carolyn Klass, Senior Extension Associate, Department of Entomology. For more information contact the Department of Entomology's Insect Diagnostic Lab
This email has been making the rounds in cyberspace:
If you use mulch around your house be very careful about buying mulch this year. After the Hurricane in New Orleans many trees were blown over. These trees were then turned into mulch and the state is trying to get rid of tons and tons of this mulch to any state or company who will come and haul it away. So it will be showing up in Home Depot and Lowes at dirt cheap prices with one huge problem; Formosan Termites will be the bonus in many of those bags. New Orleans is one of the few areas in the country were the Formosan Termites has gotten a strong hold and most of the trees blown down were already badly infested with those termites.
Now we may have the worst case of transporting a problem to all parts of the country that we have ever had. These termites can eat a house in no time at all and we have no good control against them, so tell your friends that own homes to avoid cheap mulch and know were it came from.
Comments from Barbara Thorne, termite expert at the University of Maryland:
The risk of the Formosan subterranean termite (Coptotermes formosanus) moving north via mulch produced from Katrina and Rita debris has been a lively topic of discussion. The state of Louisiana imposed a quarantine in early October that prohibits movement of wood products and debris in order to prevent the spread of the Formosan termite, but people are understandably concerned because it is impossible to enforce this type of quarantine despite the best of intentions.
Regarding mulch, termites do not have a very long half-life in a shredder, so fresh mulch is not a problem. Mulch that sits in one place for a period of weeks or months could become infested from termites underground, but based on reports from New Orleans and the gulf coast, wood is being chipped and then moved out fairly quickly to make room for more. Once mulch is bagged and stored at a distributor's or at the destination property, termites residing in the soil may pierce the plastic bags and colonize the warm, moist wood chips within. It is not uncommon to find termites within bags of mulch, especially bags lying directly on the ground, but that scenario has been going on for decades and involves local termites. A key thing to remember when mulching is to make the application as thin as possible, especially near a structure. Mulch creates a hospitable, warm, moist environment for termites to travel in or under, so to reduce the risk of structural infestation it is best to keep mulch away from buildings.
The higher risk for termite hitchhiking north from the hurricane zone is movement of construction debris, tree stumps, logs, etc. that might be infested with termites. Intact wood could readily transport termites. Movement of infested rail road ties has long been pegged as the primary mode of spread of the Formosan termite within the U.S.
Comments from Michael Merchant, Urban Entomologist Texas Cooperative Extension:
I have just conducted a little research today on the subject of this email in response to some media requests. I spoke with Louisiana termite researcher Dr. Gregg Henderson, Louisiana State University, and he informed me that there is indeed a quarantine on all wood waste from hurricane devastated areas of southern Louisiana. The quarantine specifically addresses the concern about Formosan termite-infested wood products being shipped to new areas. The state is currently debating how or whether large quantities of wood material can be treated prior to shipping to overflow landfills in Mississippi that do not currently have Formosans. However, the bottom line is that Louisiana neither encourages nor condones the sale of wood waste in mulch from the hurricane damaged areas.
If anyone is chipping, bagging and selling mulch from southern LA it is being done under the radar and illegally. The same would be true for Texas where there are also large quantities of wood from Hurricane Rita-affected areas that also have Formosan termites.
Part of the email message circulating around the Internet is accurate at least the part about Formosan termites being found in damaged trees and the POTENTIAL for Formosans to be transported in wood mulch. However, the mulching process is highly destructive to termites and the likelihood is low of transporting a viable mini-colony of Formosans in this manner. Having said that, Formosan termites have been known to be shipped in this manner at least once.
The essence of this email is a hoax, in my opinion. I believe it very unlikely that the large retailers mentioned would be buying and distributing termites from illegal sources. A far greater, and better documented risk is the sale and distribution of recycled railroad ties.
Railroad ties are commonly sold throughout the south for use as landscape timbers. Unfortunately, despite their creosote treatment, Formosan termites can easily inhabit the center (untreated) areas of railroad ties. Texas recently enacted a quarantine for this type of wood coming from Formosan-infested areas; however we are still in the process of developing enforcement protocols and I am unaware of whether inspections and stop-sale orders have yet to be enacted.
Despite the fact that I consider risks of Formosan termite infestations in mulches to be low, I am recommending that consumers be alert to the presence of termites in bagged or bulk mulches. If you open a bag and find it infested with termites you might consider resealing the bag and placing it in a larger black plastic garbage bag and exposing it to the hot sun for several days. Raising mulch temperatures to 120 degrees Fahrenheit for an hour or more is generally sufficient to kill all insect life.
Another way to ensure that you dont introduce unwanted termites into your landscape is to purchase garden mulch from a reliable, local source. Many municipalities now produce and sell mulches produced from city yard trimmings and landscape waste. This should be a safe source for mulch and is a great way to close the circle and encourage recycling of a valuable resource that would otherwise end up in a landfill.
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