According to ANSI Z60, which type of shade tree does not meet minimum quality requirements?

The correct answer pertains to a Type 2 shade tree that exhibits co-dominant stems occurring within the lower half of the crown. According to ANSI Z60 standards, minimum quality requirements for shade trees mandate well-formed structures that promote healthy growth and aesthetics. Co-dominant stems, particularly in lower portions of the tree, can lead to structural weaknesses, competition for resources, and eventually an increased risk of failure.

Such structural flaws are generally indicative of poor training or selection practices, which are specifically noted in the standards. In contrast, Type 1 shade trees with a single trunk or a clear trunk are expected to meet quality guidelines because they typically exhibit superior structural integrity and growth form. Meanwhile, a Type 2 shade tree categorized as having a moderate trunk would still generally be accepted if it aligns with other quality criteria. Therefore, the presence of co-dominant stems in the lower half of the crown disqualifies the tree from meeting the minimum standards outlined in ANSI Z60.