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Mulching is one of the most beneficial practices you can do in the landscape. Each year when I teach the Master Gardener class, I challenge them to come up with at least 20 things mulches do in the landscape that would be considered beneficial.
Somehow, we always get the question about the use of certain types of mulch and the concern for the health and safety of pets and if there are any other concerns about using mulch around the base or foundation of a house.
This week I am focusing on some of the things that may influence the type of mulch you choose, based on certain characteristics of the mulch.
One legitimate concern is about the use of cocoa bean mulch. I have researched the use of cocoa bean mulch and have found the following from the American Society for the Prevention of Cruelty to Animals (excerpts only—for the full report, go to the ASPCA Web site): “Cocoa Bean Mulch as a Cause of Methylxanthine Toxicosis in Dogs” by S. Hansen, H. Trammell, E. Dunayer, S. Gwaltney, D. Farbman and S. Khan
Cocoa bean shells, a by-product of chocolate production, are sold as mulch for landscaping. Homeowners find cocoa mulch desirable because it degrades into an organic fertilizer and provides an attractive color and odor. Unprocessed beans, derived from the Theobroma cacao plant, contain 1 to 4 percent theobromine and 0.07-0.36 percent caffeine; whereas, cocoa bean mulch contains 0.19-2.98 percent theobromine. Some dogs find the mulch attractive and eat small to large quantities.
Dogs consuming cocoa bean mulch may develop methylxanthine toxicosis. Retrospective case data suggests clinical signs following ingestion include vomiting and muscle tremors. Although oral doses could not be quantitatively determined, clinical severity increased with increasing qualitative dose descriptions; therefore, treatment should be directed at controlling clinical signs until recovery and preventing further exposure. Pet owners should avoid use of cocoa bean mulch in landscaping around dogs with indiscriminate eating habits.
1) Low doses of methylxanthines in dogs cause gastrointestinal upset;
2) High doses cause tachycardia, muscle tremors, seizures and even death;
3) Drolet documented the death of a dog after eating a large amount of cocoa bean shell mulch containing 0.46 percent theobromine;
4) Cases managed involved dogs that developed vomiting, tremors, tachycardia, hyperactivity, or diarrhea with full recovery;
5) Clinical severity appears to correlate with increasing qualitative dose descriptions;
6) Treatment of affected dogs includes multiple dose activated charcoal (2g/kg PO) and tremor control with cardiac monitoring;
7) Urinary bladder catheterization may reduce reabsorption of methylxanthines;
8) Other potential exposures include pesticides and mycotoxin-producing mold;
9) Dogs may experience clinical effects from large ingestions of cocoa bean shell mulch but life-threatening signs were not reported; and
10) It is recommend to avoid use of cocoa bean shell mulch in landscaping around unsupervised dogs.
There are still other concerns with other mulches. Termites feed on decaying organic matter and mulches that are from organic sources could be eaten by termites. Whether they get inside a house or not depends on many other factors. The short answer is they are not likely to eat down a house because of mulch and they may never cause damage to the house, but wood coming into contact with soil plus moisture will be attractive to termites. Simply keep the mulch from direct contact with wood construction materials of the house and inspect for termite tunnels periodically to avoid problems with termites. Each home should have some type of termite bond treatment for added insurance.
The use of certain types of mulch could be deemed to have more fire risks associated with them as compared to other mulches. Inorganic mulches such as rock or gravel have no fire risk since they are inorganic materials.
When all is said and done there are advantages and disadvantages in selecting the right mulch for you; however, all mulches do two great things: They conserve moisture and suppress weeds.
Next week, I will focus on the other 18-plus good things that mulching does for us.