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