Powdery mildew can decimate an acorn squash crop, but now there’s a solution - Royal Ace PM. Royal Ace PM produces big yields of high quality acorn squash. The fruit are uniform for size and shape and have an attractive dark green color. The color retention is good in storage and its flesh qualities are rated high. The large semi-bush plants have thicker foliage than other acorn varieties, but their yields and intermediate resistance to Powdery Mildew are second to none.