Control of Botrytis in peonies is a long term case. Not taking care of protection after the flowering especially, is an important factor for Botrytis causing so many problems. Make sure to spray against Botrytis so that the damage of cutting the flowers will not cause any infection. Add Magnesium (bitter salt) to the Botrytis spray to harden off the plants.
In the fall the fungus will form winter spores which will winter on the soil/air. This is also the spot where the infestation starts in the spring. Thus control is needed in the spring, but the basis lies in the after-summer. The now much used Collis in the spring is absolutely not a total solution, but a part of the solution. Research has shown that not cutting the plants too short (+/- 10 cm above the soil) in the fall, has a Botrytis preventive effect and thus will decrease the chance of falling over of the stems the following spring.
On the left: Example of damaged in Peony. On the right: Left Botrytis and right leaf spot damage.
Weeds
Leaf nematodes in weeds can infect a parcel.
It is important to totally control weeds during the summer. Especially with street grass, this weed control cannot be used in peonies. This product is taken by the plant through the roots. For a weed infected parcel the only product left is Basta. It is possible to add some ureum. If a lot of street grass is present it is useful to add a small quantity of Chloorprofam to the Basta.
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