3:39 Now HLB is in California. It has been detected in 2,000 trees but not yet in commercial orchards. But there is hope on the horizon. University of California Riverside (UCR) researchers and their partners are perfecting a fruit that may be resistant to the greening disease. Through genetic engineering, UCR scientists like Mikeal Roose is crossing U.S. varieties with Australian ones. A fruit down under similar to a lemon or lime, seems to have some resistance. Roose is crossing the U.S. variety with an Australian one and then again with an American citrus fruit. "It's still a little bit difficult but it's doable," he says.