[Arid_gardener] Re: Tangelo Blossom Drop

[Olin Miller]

----- Original Message ----- 
From: <mariasmate at aol.com>
To: <arid_gardener at Ag.arizona.edu>
Sent: Saturday, March 31, 2007 10:41 AM
Subject: [Arid_gardener] Question from Home-Hort WWW page
> allen bleicher
> 85032
> mariasmate at aol.com
> tangelo tree showing more blossoms than in last several years.   please,
> what can i do to help them set and not fall off before fruiting as they
> have in past.  thanks so much
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Some considerations:

1.  Pollination - Most citrus varieties are self-fertile but many of the
mandarins, including tangelos ,and mandarin hybrids, are only weakly
self-fertile and require pollination by insects to be very productive
according to a University of Florida article "Pollination of Citrus by
Honeybees" at
http://edis.ifas.ufl.edu/AA092
Thus it helps to have another mandarin pollenizer tree close by.  According
to the article, Minneola (Duncan grapefruit and Dancy mandarin) and Orlando
(Duncan grapefruit and Dancy mandarin crosses) tangelos require cross
pollination.  With crosspollination, there will be more fruit with more
seeds and the tree will bear every year.  With no or very little cross
pollination there will be less fruit with fewer seeds and the tree will tend
to produce only every other year.  Planting an appropriate pollenizer tree
would help but there isn't much one can do about  the bee problems.  The
beekeeping industry is already fragile from the varroa mite problem and is
now becoming threatened again by the Colony Collapse Disorder problem that
may be even more serious.

2.  Citrus flowers are sensitive to cold and a cold spell after the flowers
started to appear could also result in some blossom drop.  Unfortunately
there isn't much one can do about this either.

3.  Citrus flowers are sensitive to water stress so be sure to water
correctly at all times but especially during the flowering period.  Refer to
the publication "Irrigating Citrus Trees" at
http://cals.arizona.edu/pubs/crops/az1151.pdf
for the U of A irrigating recommendations.

4.  Winter pruning can reduce spring flowering.

5.  Homeowners in Youngtown and in some Southern areas of Sun City believe
that high winds last spring caused blossoms to drop prematurely.

Olin Miller, Master Gardener Volunteer, Maricopa County AZ

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