For a few weeks in April the palo verdes along the Salt River bed go off like slow yellow fireworks, and then they drop every bit of it onto the lawns below. Tree Pros keeps those shaded Phoenix yards mowed, edged and trimmed, raking out the blossom, seed pods and leaf drop that collect under mesquite and ash. Grass beneath trees is a different animal — thinner, patchier, dappled all day — and it asks for a lighter, more attentive cut. Done well, a yard reads as one piece from fence to fence, with the shade a gift instead of a problem. It is good work to finish in the cool under a big canopy, the river bed running green in the distance.