Drought affect on stone fruit flower bud formation

I’ve learned a lot about the effect of drought on stone fruit flower bud formation and fruit set in the following year. I’ve used water deficit to increase brix of stone fruit. Doing that can severely affect bloom the next year. The fruits most affected are sweet cherry and apricot. Pluots to a lesser extent. Japanese plums seem little affected. Peaches and nectarines none at all.

Flower buds are formed in early summer of the prior year so now is the time to be concerned about next years bloom.

The effect on apricots is normal appearing flower buds that begin to swell in spring but stop and eventually fall off without flowering. Crop loss can be nearly 100%. Sweet cherries in contrast bloom and appear normal. But flower buds have little or no pollen and the flower parts are abnormal. Crop loss in cherry can be 100%. Pluots being part apricot and part plum seem to be less affected than apricot but still 50% or more of buds may fail to develop in spring.

Achieving high brix and still having good bloom requires a balancing act which I need to work on further. At times I’ve gone too dry to even set a crop the next year.


Thanks for your observations.


Thank you for this info. Did you just water your trees less to observe drought? How often did you water them?

I deep water all my tree once a week, would you recommend going every 10 days instead, I have good mulching, i haven’t really checked under the mulch after 7 days I just do it consistently.

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Hi John: I can’t tell you how often or how much to water. You have to do this by trial and error. But I would say that to achieve high brix you may need to cut water to about half of full irrigation. So if you’ve been applying two inches a week try one. Then you can see if the fruit is sweeter and how the trees behave the next year. Do they bloom and set normally. You need to learn to read the trees. I can say that if they start to drop leaves they are too dry.

The greenhouse is a milder environment than outdoors. Water needs of the trees are less. I was applying about 3 inches a month.

Mainly my comments about deficit irrigation, drought, and bloom were to help those trying this growing technique understand how their trees might react. If your trees are so dry that they won’t bloom next year that’s too dry.

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I have a couple of 12 year old established apricot trees, they find their own water. The water table is about 10’ below ground. With no rain during the blooming season, almost all or many of the blossoms set fruit. more than half of the fruitlets needed thinning. In the past with heavy rains during fruit set, many or most would be lost, others to mildew. This year will be great on the other hand we are in a severe drought, East Palo Alto CA, less than a mile from the bay.

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