Blackberry canes are biennial, living
for two years. Blackberries send up new shoots (primocanes) from
crown or buds formed on the roots. These canes produce no flowers or
fruit the first year. The second year these canes are called
floricanes. These are the canes that flower and produce fruit.
Floricanes gradually die after fruiting. Old floricanes should be
removed and burned immediately after fruiting, usually late June or
early July in Louisiana.
Pyzner recommends severe summer pruning on varieties that are highly
susceptible to rosette disease and are located in areas where rosette
disease is prevalent.
The horticulturist says that removing the new primocanes with the old
floricanes immediately after harvest eliminates spring rosette
infections in the primocanes. One way to do this is to mow all the
canes to the ground.
Apply fertilizer immediately after harvest as a band on both sides of
the row at a rate of one cup of ammonium nitrate or three cups of
13-13-13 fertilizer per 24 feet. of row. Fertilizing will force new
cane growth.
New primocanes should be topped in the summer when they reach a
height of 3 to 4 feet. Growers will need to top the canes throughout
the season since the canes emerge at different times. Topping the
primocanes in the summer promotes self-supporting plants and
encourages lateral branch development, which increases fruit
production the following year.
Select four to six canes per lineal foot of row for next year’s
fruiting wood. Cut lateral branches back to about 12 inches before
growth starts in the spring.
Prune trailing blackberries by selecting the best four to eight canes
and tying them to supports. Remove extra primocanes and old fruiting
canes.
For related horticulture topics, click on the Lawn and Garden link at
the LSU AgCenter Web site,
www.lsuagcenter.com.
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