Tropical Hibiscus flower buds appear to be cut off
My 20 year old tropical hibiscus is loaded with buds, but they appear to be cleanly cut off and fall to the ground before opening. Every bud stem on the entire plant seems to have about a 60 degree bend in the stem about an inch below the bud. Eventually, the bend develops a faint ring-type line around the stem at that bend point and the bud seems to break off cleanly--like it's been cut off. I am seeing no insects of any sort on the plant. I have recently worked Bonide granular insect control into the dirt because the Extension garden expert on WCCO on Sun. mornings was posed this question and she said it could be an insect in the dirt. Other than the buds dropping off, the plant looks very healthy. I keep it watered and have apply Miracle grow in the water a couple times a month. I have never had this issue in the 20 years I have kept the plant. Any suggestions? Other than sending a photo on my phone, I am computer illiterate and don't know how to attach a photo.
Steele County Minnesota hibiscus
The bud drop is probably due to temps above 90 F. I don’t think thrips are causing it because thrips eat the bud from the inside out. If the buds fall off after we get some cooler weather I would look harder for insects, although the systemic insecticide should kill them once it spreads through the plant. https://www.bhg.com/gardening/flowers/perennials/hibiscus-buds-falling-off/