Download Buxus diseases update February 2014

Buxus diseases – update February 2014
The humid summers of the last years have caused heavy mould infections on Buxus in entire Europe.
The disease is also spread in the United States, Canada and New Zealand.
Two different moulds occur : Cylindrocladium buxicola and Volutella buxi. Both moulds cause dying
leaves and branches. The disease usually starts with Cylindrocladium and may be followed by a
secondary infection of Volutella. Therefore both moulds need to be attacked.

Description of Cylindrocladium :
The infection starts with black spots on the leaves. After a few days all the affected leaves
start falling off and black stripes appear on the young twigs.

Description of Volutella :
The infection starts with the leaves turning brown, then wither and temporarily remain fixed on
the plant. The other side of the leaves pale pink mould spores appear.
These diseases can be controlled when treated correctly and on time. Gardens with a lot of Buxus a
preventive approach is recommended. When no treatment is applied, the damage can be huge. This
scenario usually begins with a few small spots, which turn into large infected areas the second year.
The biggest harm will be done in the summer and fall, especially in humid circumstances. Extra
caution should certainly be necessary especially after heavy rain.
Infected plants will recover complete after a proper treatment.
Treatment
 Multiple treatments are necessary to control the diseases. A good alternation of the used
fungicides is the best way to prevent resistance. There are not so many products allowed in
Europe and some products are not available for private gardeners.
 During dry periods you can extend the terms because there is less chance for diseases.
During wet periods you have to be extra vigilant, even until the end of October.
 Gardens with a lot of Buxus or gardens that already have been infected 4 à 5 treatments are
necessary. This is very important to stop the diseases.


The schedule below will give the best results at this moment:
P. Time
product
active substance
dose/10 liter water
remarks
May
Eminent
tetraconazool
7.5 ml
max.3x/year
June
Eminent
tetraconazool
7.5 ml
max.3x/year
July
Eminent
tetraconazool
7.5 ml
max.3x/year
August
Topsin M
+Sporgon
thiofanaat-methyl
prochloraz
20 ml
10 gr
September
Topsin M
+Sporgon
thiofanaat-methyl
prochloraz
20 ml
10 gr
Following products are also very effective: Candit ,Ortiva Top en products on base of copper
(preventif).
The phyto regulation in Europe changes a lot. Not all products are allowed in every country.
Prevention
By using a number of correct measures the disease can significantly be diminished.
 A good hygiene is advised but this is no guarantee that the disease will not occur. Avoid
contact between infected and healthy plants. Disinfecting hedge shears is not effective. A
good treatment with fungicides after clipping is a better way to avoid infection.
 In gardens with automatic irrigation it’s better, in periods of drought, to give a lot of water once
a week than spray every day.
This way the plants can dry better and the mould will have less chance. The use of drop
irrigation is also recommended.
 Judicious fertilizing can also prevent much harm. Plants that grow calmly are less susceptible
to disease. The use of coated fertilizers is therefore preferred. Over fertilizing must definitely
be avoided.
 The way we use Buxus also affects the preventing of these diseases. Tight solids, trimmed
shapes and clouds are much more sensible than naturally grown bushes. Some extra care in
such gardens is certainly advised.
 Variety in the assortment can also prevent a lot of problems. Avoiding sensible species must
be considered. Some sorts of Buxus appear to be non- or little susceptible.
Conclusion
We are confronted more and more with long, humid periods in the growing months, possibly as a
result of global warming. These circumstances in particular stimulate moulds on plants. Buxus is
affect by this as well. Because of the prejudice that nothing could happen to Buxus, these mould
infections are not or little attended to. Because of the poor knowledge of these moulds, wrong
advises were often given. An adequate follow-up and treatment are, according to me, the only
solution to keep this epidemic under control.
At this moment the use of less sensible Buxus species is recommended, especially when the
treatment schedule isn’t followed. On long term the best solution are resistant cultivars. We are
working hard on our breeding program and expect results in short term.
Buxus still remains one of the most grateful plans for the garden, in spite of these diseases. The
problem will occur less in dry summers are in dry areas. I therefore wish you a beautiful, dry
summer.
Didier Hermans,
Buxus grower
www.herplant.be
www.buxusshop.be
www.buxuscare.com