Q: Several dogs with unknown owners have been pooping and peeing on my front lawn. Is there some ultrasonic gadget that would keep them away? — Josh Swaney, Conyers
A: Sound repellers have been tested almost invariably on rodents and insects — which are not analogous to dogs. The first issue, of course, is that these repellers are making only sound. The theory is that dogs will be surprised and irritated, and therefore will avoid the area. Rural dogs might try to avoid ultrasonic sound, but canines in urban areas hear extremely high sound frequencies all the time and can become conditioned to them.
It’s not the frequency of the sound that makes a difference to a dog: it is how unusual and threatening it is to them. If he finds the sound frightening, a dog will theoretically stay away. The second problem is that, the higher the sound frequency, the smaller its beam width, so it covers only a limited area. So it’s not particularly useful if you are trying to cover a large area. Ultrasonic repellers do not work to repel any animal unless you throw it at them.
Q: Do you have any resources for pesticide-free wheat straw near Atlanta? — Corinne Matthews, email
A: Just like you can’t know the food you buy at the organic grocery is truly organic unless you know everyone down the line to the farm from which it came, you can’t know your straw is pesticide free unless you know everyone in the chain of production all the way back to the farm.
You may choose to work with a person due to their good reputation, but every step of production is as important as the last, much like the links of a chain. If you have the time and the storage area, you could conduct a bioassay. Put a couple of bean or tomato seedlings in a paper cup that has been filled with a mixture of your chopped straw and potting soil. If these plants grow weirdly within a couple of weeks, that straw should not be used near garden plants.
Q: I have what I think are three Frazier fir trees; one has no green on it at all. I assume it had a fungus. Is there something I should spray on the others to keep them from getting whatever it is? There are some kind of white patches on the trees. — Lisa Hynson, email
A: The tree that doesn’t have green is dead. It will make good firewood. Without knowing what kind of trees you have and more details on symptoms, it’s impossible to tell what killed the first tree or what you should do with the others. I remain at your service by email each week at The Atlanta Journal-Constitution.
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