I was given 2 small fig trees (7 leaves on one, 3 on the other). Carefully planted them outside. The smaller one (3 leaves) is growing and doing great. But, the bigger one is struggling (but still growing). The lower leaves are mottled, getting yellow and curling. Undersides have gritty, dirty looking black particles that easily wash off. I thought it was insects, so I sprayed with water and they washed off. Back again in 2 days. Sprayed with neem oil/detergent/water spray. Back again in 3 days. The other fig is planted only 20 feet away and is fine, The same thing happened to a potted tropical hibiscus, but one treatment with the neem spray solved the problem. Help! I care for both figs in exactly the same way.