have some junipers, both as bonsai and as potplants. A number of
them are showing some serious dieback for unexplained reasons. They
get watered properly, yet branches slowly go a dull colour and die
off. Light feeding doesn't help either. Is there a soil disease
that might cause this and how would I treat it?
this plant just started showing signs of dieback or has it been
gradual? Junipers do not like hot, humid weather, so if you live
in Auckland, that could be (part of) the problem. It is also possible
the plant could be affected by a root disorder such as Phytophthora.
The most common cause of this is plants going through a period of
drought and then being watered.
Cut back the infected
foliage and dispose of it in the rubbish bin or burn it to stop
the disease spreading.
There is a spray to control
root disorders called Ridomil but I do not know of it being
available in small quantities for the home gardener.
Once the plant is infected,
there isn't a lot that can be done, other than cutting it back and
hoping it recovers.
Junipers do not need
regular feeding. Feed in spring with a controlled release fertiliser
such as Osmocote. A quality potting mix will have enough fertiliser
in it to feed the plant for up to three months, then feed again
the following spring. An occasional liquid feed with Nitrosol will
benefit the plant.
Junipers require full
sun and a well-drained potting mix or soil.
I would suggest a sample
of the dieback be taken to your local garden centre for identification
they should be able to assist in identifying the problem.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH