&middotDrought damage - needles gradually turn yellowish-green and then light brown. This starts at the top of the tree and progresses downward and from the outside in. &middotAnimal injury - dog urine can cause some browning and dropping of lower branches on arborvitae and junipers.
There are many different brands of cat flea collars. Generally, flea collars work by either emitting a toxic gas to the local area (head/neck of the pet) or by exuding chemicals that are absorbed into the animal's skin. Some flea collars have an Insect Growth Regulator (IGR), to prevent development of cat fleas, eggs and larvae.
| The Bug Squad that concerns about flea collars. The link said there are many types of flea collars like absorption-based, gas based and etc. It also describes the positive and negative effects. I never attached flea collars on my dogs, plus it can instill long term problems on my pets.