Michigan Right-of-Way Pest Management Practice Exam

The recommended time frame for trunk injection of gibberellin inhibitors in the Northern US is during bud break in spring and after leaf drop in fall. This timing is critical as gibberellin plays a significant role in the growth and development of many plant species, influencing processes such as stem elongation, flowering, and fruit development.

During bud break in spring, plants begin to emerge from dormancy, and gibberellin levels rise to promote growth. Injecting gibberellin inhibitors at this stage can help manage excessive growth and ensure that the plant maintains a desirable form and health throughout the growing season. Furthermore, applying the inhibitors after leaf drop in the fall allows for control of the plant's growth responses as it enters dormancy, thus preventing irregular growth patterns that might occur if the inhibitors were applied at other times.

This strategic timing helps to optimize the effectiveness of the treatments and ensures that the plants can respond appropriately to them, maintaining vigor and health while minimizing issues associated with overgrowth. Understanding the correct application period is essential for effective pest management and overall plant health in the Northern US.