A rat guard is a simple, non-toxic physical barrier designed to protect the lower trunk of trees from rodent damage. This guard acts as a shield, preventing rats and other climbing rodents from accessing and chewing the tender bark. The primary purpose is to safeguard the tree’s vascular system, which is located just beneath the outer bark. Creating an effective guard at home is a straightforward, budget-friendly project that ensures the long-term health and survival of your trees.
Understanding the Threat to Tree Health
The damage caused by rats and other rodents, such as voles, is a serious threat to a tree’s survival, particularly during winter or periods of drought. Rodents seek the inner bark for its moisture and concentrated sugar content when other food sources are scarce. When a rat chews the bark, it scrapes away the phloem and the cambium layer, which transports nutrients and water between the roots and the leaves.
This damage is known as girdling, where the bark is removed in a complete ring around the trunk. If girdling extends all the way around the trunk, the tree’s internal communication system is severed, and the tree will likely die. Young trees with thin, smooth bark are especially vulnerable because the protective outer layer is easily breached.
Essential Materials for DIY Rat Guards
The foundation of a durable rat guard is galvanized hardware cloth, a metal mesh that rodents cannot chew through. For maximum protection against smaller rodents like mice and voles, select a 1/4-inch mesh size, though 1/2-inch is effective against rats. Choose galvanized material because the zinc coating resists rust and corrosion, allowing the guard to last for many years outdoors.
You will need heavy-duty wire cutters or tin snips to cut the mesh, and a tape measure for proper sizing. For assembly, use durable securing mechanisms like heavy-duty zip ties, thin rubber-coated wire, or hog rings to fasten the edges. Always wear thick work gloves and safety glasses when handling hardware cloth, as the cut edges are extremely sharp.
Step-by-Step Guard Construction and Installation
Start by determining the necessary dimensions for your tree guard. The height should be 24 to 36 inches, accounting for deep snow cover and the climbing ability of rats. To calculate the length, measure the trunk circumference and add an extra two to three inches. This allowance ensures the guard does not rub against the trunk and provides room for the tree to expand.
Using tin snips, carefully cut the measured piece of hardware cloth from the roll. Overlap the two vertical ends by at least one inch, or two to three mesh squares, to create the cylindrical form.
Secure the overlapping seam by threading heavy-duty zip ties or wire through the mesh squares at the top, middle, and bottom. Pull these ties tight to lock the overlap in place, creating a firm, rigid cylinder. The finished guard must have a diameter significantly wider than the trunk, allowing for several inches of air space around the tree.
To install the guard, slide the completed cylinder over the trunk and center it. Gently push and twist the bottom edge one to two inches into the soil surface. This burial prevents rats, voles, and other burrowing rodents from tunneling underneath the guard. For added stability, secure the guard to the ground using U-shaped sod staples pounded through the bottom mesh squares.
Ensuring Long-Term Effectiveness and Fit
For the rat guard to remain effective, it requires annual inspection and occasional adjustment. The guard must always maintain a loose fit to accommodate the tree’s natural expansion. A guard that is too tight can cause damage by physically constricting the trunk, which is a form of self-girdling.
Check the guard every 12 to 18 months, especially before the winter season when rodent activity increases. If the trunk is pressing against the mesh, the wire ties can be removed to allow the guard to expand slightly, or the entire guard may need replacement. Confirm the bottom edge remains slightly embedded in the soil to deter burrowing, and clear away any accumulated debris or mulch from inside the guard, as this can provide cover for rodents.