Friday, March 3, 2017

Warm spring, challenging pruning and cold temperatures ahead



Pruned field of Navaho blackberry, Guilford Co. NC
Yesterday the NC Cooperative Extension County offices in Guilford and Rockingham Counties held a joint blueberry and blackberry pruning demonstration in Guilford County. The pruning demo had been planned in the fall of 2016, with the thought that the first few days of March would be ideal time to prune. That is, plants are transitioning from winter dormancy to spring but buds are not yet swelling or opening. But February 2017 was much warmer than usual, so bud break had already occured on blackberry and blueberry. This is NOT a good time to prune because as you prune, you pull those removed canes through the canopy and you may accidently rub off buds on canes that remain.  The grower was wise and had already pruned all but 3 plants earlier this winter (see picuture above). 

A close up of these canes shows that the buds that are furthest out on the canes are more advanced on some canes (foreground), while other canes had very little bud break (background). The open buds could easily be broken or rubbed off during pruning.

With the predicted lows into the 20's this weekend, there is a potential for damage to flowers in the blackberry buds.  Research has shown that unlike strawberry or blueberry ALL stages of flowers in blackberry are killed when the plant temperature is at 27 F. 


Growers should monitor their fields and record the low temperatures. Check buds the day after the freeze and look to see if there is any damage in the center of the buds. See images below. 
Damaged blackberry bud (photo taken 2014).

Healthy blackberry bud (photo taken 2014).

We have posted lots of information on this site before. Here is a quick link to some of that information.


 




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