Seems like many gardeners are contending with rats these days. They eat vegetables and have been damaging citrus trees. They gnaw the bark off of citrus trees, or chew off twigs, or chew the rind from the fruit. As promised in this week's column, here is information that was in a recent column about rats, including links to two very good information sheets on the animals:
One reader reported good results from using an aluminum trunk band on a fruit tree trunk. Thsi can help if it is 12 inches wide and there is no other way into a tree. Repellent granules may also help. Traps are effective when used well, and pest-control professionals can be hired to set them. (One way to locate licensed trappers is through the Web site www.wildlife-removal.com). Rat bait is the worst idea, since the poisoned rats are likely to lbe eaten by cats or birds of prey, which will be killed by poisoned rats.
It is important to understand that urban rats are a community problem, not necessarily solvable by one gardener working alone to protect one tree or one vegetable garden. Rats multiply when they can get into houses, have access to food (garbage, pet food, birdseed, etc.) and have cover (ivy on fences, heavy ground cover, trash). As the lemon rind story shows, if you have rats, your neighbor does too.
City health department inspectors will survey a property for possible attractants and habitats, and advise on how to remove them. They will also cite individuals with documented rat-attracting conditions who refuse to remove them. (To report a rat problem in San Francisco, call 311.) But perhaps a better approach is a community effort, such as a block party to seal up buildings, clean up and get a neighborhood rat problem under control. I found two downloadable rat information sheets that explain the tasks necessary to make a neighborhood rat-unfriendly. One is at the San Francisco Health Department Vector Control site (www.sfdph.org/dph/files/EHSdocs/ehsPublsdocs/pests/Rats_and_Mice.pdf).
The second information sheet (www.hungryowl.org/rodenticide.pdf) is on the Web site of the Hungry Owl Project. This Marin County nonprofit helps Bay Area residents set up barn owl nests so these raptors can provide natural rodent control, and also offers good advice on other environmentally safe ways to control pest rodents.