The most effective deterrent for any cat is a spray of water, and that's exactly what happens when the Contech CRO101 Scarecrow Motion Activated Sprinkler is used. Place this device into the ground using the included stake, attach it to an outdoor hose faucet, turn it on and let the motion activated sensor do the work. When a cat triggers the sensor, a sharp blast of water sprays the cat. This motion activated sprinkler will cover up to 1000 square feet, and any cat within that radius will get sprayed, depending on the water pressure in your water system. There is no finer and more effective cat deterrent than this one, but just remember to turn it off before you go outside, or you will be in for a wet surprise!
For a hi-tech solution to problem cats, try the Yard Sentinel Ultrasonic Outdoor Pest & Animal Repellent. This unit emits pulses of ultrasonic sound that can be heard during coverage of up to 5000 square feet. There are several different settings, like continuous, motion sensor activation or a sweep mode, that will fit the needs of your property. It runs either on an AC adapter, a vehicle 12 volt socket or it can be battery powered for places that have no readily available electricity, and for the utmost in convenience, the battery will continue to work the device if the AC power goes out.
For the best in an organic spray, get Messina Wildlife CA-U-016 Cat Stopper. This formula sprays on vegetables, shrubs, dirt, sand and anywhere else a cat may be partial to. Its totally organic ingredients make it safe to use in virtually any situation, and it is resistant to rain washing it off. It stops a cat from spraying, leaving droppings, scratching and bedding down. It dries clear in about 20 minutes, and works by small, taste and feel. It will not stain clothing or other materials, and this is the best bang for the buck product here.
For the most unique idea in a cat repellent, look no further than U Scram Cat & Chipmunk Deterrent. This system puts up an invisible fence around an area that you want protected, and allows you to target specific places, like gardens or sandboxes, using only scent as a deterrent. U Scram employs essential oils that cats hate, placed on little triangular cork trees that press into the ground around an area you want protected. One whiff and the cat will take off running. The oils will not wash off and they can be easily re-soaked with essential oils when their effectiveness wanes. Organic, non-toxic and biodegradable, it will keep cats from entering any area where the cork trees have been deployed.
To target specific areas where cats congregate, use Liquid Fence Dog & Cat Repellent. This repellent works by altering the scent of any specific area that it is sprayed on. For example, if sand doesn't smell like sand, a cat will not use it as a litter box. Biodegradable and earth friendly, it can be sprayed on plants, trees, gardens or anywhere a cat may want to use or reside in. Although resistant to rain, reapplication should be done weekly for maximum effectiveness. Always check on small pieces of woodwork or material to make sure it doesn't stain before application, but it is non-toxic for both plants and animals and it is easy to use.