What could be the cause of this bud drop.

[davidwood]

The last 6 buds on my Think Pink have all just fallen of. As the photo shows and they are all the same it seems to break of about an eighth of an inch down the stem.  Any ideas please.

[helixturnhelix]

Thats frustrating David, it looks like they are still green, so that probably means no pests.  I know that I get lots of bud drop when the environment changes quickly, like one random day of being triple digits in a month that has been in the 80s.  Any sudden weather changes in your area?

[davidwood]

Actualy there has been a lowering of temperatures but this has now gone on for a month, very strange as there is nothing happening to any of the other cv's. The only blooms i have had [2] are from buds that where on the plant when it arived. All new buds are just falling off.

This is a slightly smaller bud from last week but as you can see it seems to break in the same place.

Chris now i think about it what you say about change may have a bearing, since it has arived i have been protecting it from to much sun. It will be interesting to hear Charlies view, and if its sun and needs more i can soon put that right.

[Charlie]

This is one of those "scratch your head and wonder why" problems. Normally I would say it is thrips since they can saw off the bud right at that spot - its part of the reproductive behavior that sends the egg implanted bud into the dirt where the larvae can burrow down. But, they are on the small side for buds with thrips to fall, and thrips rarely bother only 1 plant when others are also available. Whenever I suspect thrips even if the evidence is not all there I treat with spinosad and have found that the problem clears up more times than not.

So if not thrips, then what? Environmental stress is most likely because it can cause release of the plant hormone abscisic acid (ABA) which in turn can cause abscission (dropping) of buds. Another hormone, auxin, works against the action of ABA so that suggests that spraying the hibiscus with Supernova which has auxins in it might stop the dropping of the buds. I suggest trying that next. You can both mix it into the irrigation water and spray it on the plant. Spraying has the quicker result. Spray daily for a week to see if this stops the bud drop.

I doubt it is the lack of sunlight - if there is enough for the plant to form new buds then that should be enough for the buds to continue to develop to blooming. Even so it might help to move them to a slightly sunnier spot. Keep in mind that low water is a stressor that can activate ABA so don't let them dry out completely in the sunnier spot.

Let us know what happens.

Charlie