PPDL Picture of the Week

June 19, 2017

Freeze Damage in Red Raspberries and Blackberries: The Sequel

Bruce Bordelon, Professor, Department of Horticulture and Landscape Architecture, Purdue University

I wrote about freeze damage in red raspberries and blackberries earlier this year after we had a very warm February followed by a hard freeze event in March.  I noted that while damage to many plants was very obvious, damage to some of our fruiting plants, particularly red raspberries and blackberries was much less obvious. Well, now that the season has progressed, we are seeing the full extent of the damage.

The leaves of Heritage red raspberries were damaged by the cold temperatures in mid-March.  We noted that excised buds showed a dead growing point inside the main bud, but that multiple buds occur on raspberries. Now we are seeing that for many of the floricanes, the damage to the vascular system beneath the buds was severe enough that the fruiting lateral shoots are weak, and in many cases dying (Fig1) The damage is worst on the upper portions of the canes that were more advanced when the freeze occurred. Fruiting laterals from the lower buds appear normal. (Fig2).

Blackberries cultivars vary in damage. Some have significant damage to floricanes and reduced potential for a crop this season. Others have a partial crop. One major concern is that many of the fruiting lateral shoots have almost no leaflets (Fig3). Even though the flowers were undamaged and set fruit, it is unlikely the fruit will ripen normally since there is not enough leaf area to support the crop. Others have damage to flowers as well, with reduced fruit set and poor fruiting lateral development (Fig 4 and 5).

Primocanes on these damaged plants are normal and healthy, so there is potential for a good crop next year.

​Clic​k image to enlarge

 
Fig1: Heritage red raspberry canes with dead fruiting laterals

 

Fig2: Heritage red raspberry canes showing growth of fruiting laterals from healthy at the base to dead at the tip

 

Fig3: Natchez blackberry fruiting laterals with good fruit set, but few leaves.

 

Fig4: Ouachita blackberry fruiting laterals showing weak growth and poor fruit set


Fig5: Ouachita blackberry floricane showing many dead and weak laterals.