Which statement is true regarding TGRs (Tree Growth Regulators)?

Tree Growth Regulators (TGRs) are substances that influence the growth of trees, primarily by inhibiting certain growth processes. The statement that TGRs are most effective when applied to slow-growing trees is supported by the fact that slow-growing trees often have more pronounced responses to growth regulation. When applied to these types of trees, TGRs can help control height, reduce excessive growth, and improve overall tree structure and health.

Slow-growing trees typically have a more manageable growth rate, which allows TGRs to effectively reduce apical dominance (the phenomenon where the main central stem grows more actively than other stems) and promote a more balanced growth habit. This is particularly beneficial in settings where space is limited, such as urban landscapes, allowing for better management of the tree's size and form over time.

In contrast, TGRs are not as effective on fast-growing trees, as these trees may not respond in the same way due to their naturally rapid growth rates. There’s also the misconception that they are ineffective for slow-growing trees; however, this overlooks the specific benefits that TGRs can provide in optimizing growth patterns and health for these varieties.

Thus, applying TGRs to slow-growing trees can lead to improved structure and stability