SAN FRANCISCO (AP) – As wildfire risks heat up, Silicon Valley startups are starting to take notice. Companies face multiple barriers in this field, including stodgy utilities and government agencies, but investors are encouraged that activity is picking up. One startup makes a fire retardant spray that is safe for plants and designed to keep fires from spreading. Another using artificial intelligence technology to spot fires as soon as they break out. One more uses drones to replant trees after a fire ravages a landscape. Founders are hopeful more tech companies will get involved as wildfires continue to occur in California and Australia.