[NAFEX] Blackberry fruits that are white or won't developfully

Brungardt, Sam Sam.Brungardt at state.mn.us
Fri Mar 12 12:37:17 EST 2004


Thanks for your observations, Jim.  Your comments led me to use some different terms in my Google search and I found the answers.  Overhead watering could indeed play a role, since water setting on the berries and exposed to strong sunlight and high temperatures will become overheated.  

This morning I happened across a source (http://www.ppdl.purdue.edu/ppd/expert/Blackberries.html) that mentioned "blond" drupelets on blackberries.  It said several causal agents have been implicated as the cause.  One is sunburn or sunscald from UV radiation and exposure to high temperatures. Another possible cause is feeding by tarnished plant bugs.

Chapter 2 of the "Midwest Small Fruit Pest Management Handbook" (http://ohioline.osu.edu/b861/b861_34.html) says, "Malformed berries or failed druplets result from tarnished plant bug feeding on mature fruit....Other plant bug species and stink bugs can cause similar damage."

As to what causes berries that never mature properly, cause is sunburn (and this makes sense, since these small, hard berries on my 'Illini Hardy' plants are at the end of the floricanes, where the foliage is sparse.)  One source (http:extension.oregonstate.edu/news/story.php?S_No=580&storyType=garden&cmd=pf) said about sunburn: "In blackberries, the dark colored fruits absorb heat, especially on the sun-exposed side.  When sunburned, droplets [sic] of trailing varieties can become red and soft and taste overripe.  But they are still edible.   In erect varieties of blackberries, the fruit may become hard and dried, rendering them inedible."

Sam Brungardt, Saint Paul, Minn. (USDA Zone 4b) 

-----Original Message-----
From: nafex-bounces at lists.ibiblio.org
[mailto:nafex-bounces at lists.ibiblio.org]On Behalf Of Jim Cooper
Sent: Wednesday, March 10, 2004 11:21 AM
To: nafex at lists.ibiblio.org
Subject: Re: [NAFEX] Blackberry fruits that are white or won't
developfully

I think the white color is related to overhead watering. I have had the
same problem, but in only some areas. These areas are open to the taller
sprinkler and the water sits on the fruit too long. I've gone to using a
soaker hose, or low sprinker near the ground.
Jim In Idaho
growing Navaho thornless Blackberries
zone 6

1. Some of the developing 'Illini Hardy' fruits turn partially white,
making them very unattractive.  Is this weather or cultivar related, or
is there something I can do to remedy this?

This may also be related to water???

2. As the picking season ends, many of the last fruits set do not
develop as they should.  Instead, they never get large, and they are
hard and tasteless.  Again, can I do anything about this, or should I
just accept that the last fruits to set often do not develop fully?

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