A: Realistically, there are no rodenticides that are completely safe for nontarget species like owls, bobcats and coyotes. Poisons such as brodifacoum, bromadiolone, and difethialone are single-dose rodenticides. These poisons kill quickly, usually within a day of ingestion. Once eaten, the drug is stored in the liver and prevents blood clotting. Since these drugs are not excreted before the rodent dies, predators and scavengers can be poisoned. If you have any of these rodenticides, please do not use them, and dispose of them properly.

Older poisons such as warfarin, chlorophacinone and diphacinone are multiple-dose rodenticides. These are generally considered to be less harmful to wildlife but can cause problems if a predator or scavenger consumes multiple rodents that have been poisoned. To minimize the risk of secondary poisoning of wildlife or pets, follow the instructions on the label closely. Promptly remove and dispose of any dead rodents by sealing in a plastic bag and disposing in a secure trash container. Don’t handle dead rodents with bare hands. Buried rodents can be exhumed by dogs or coyotes.

If possible, find other ways to kill rodents. I prefer the electrocution-type traps since they are humane and easy to use. Never use sticky traps outdoors since they are more likely to catch nontarget animals and are inhumane. For more information on rat control, see ipm.ucanr.edu (search “rat pest notes”).

Q: My New Year’s resolution is to clean out my garage and get rid of any pesticides that are expired, not needed or harmful to wildlife. How do I find out what I should get rid of? Do fertilizers have an expiration date?

A: This is an excellent New Year’s resolution! If you have any pesticides that are expired or not needed anymore, make sure they are labeled (hopefully with the original) and place them in a sturdy box so you can take them to your nearest hazardous materials disposal site. Fertilizers don’t really expire, but they may become clumpy and unusable, so these can be disposed of in a similar way.

The laws concerning pesticides change frequently, so it’s always a good idea to take inventory and get rid of any chemicals that are no longer considered safe to use. Take note of the active ingredient(s), which should be listed on the front of the container, and look them up on the University of California’s IPM website (ipm.ucanr.edu, search “pesticides in homes and landscapes”). There you can find an active ingredient index that will give you information on precautions, how it works and possible adverse effects, . There is also a list of less toxic alternatives.

When you are ready to dispose of your old pesticides, fertilizers and other household chemicals, you can find a drop-off site by searching “Household Hazardous Waste + (your county)”. Alternatively, your waste management company’s website should also have this information.

Have questions? Email gardening@scng.com.