Peony Care Newsletter May 2016

Dear Peony grower / breeder,

Herewith we send you our Peony Newsletter. Information currently relevant to the crop of peonies will be given special attention. We trust that this information will be helpful in achieving a successful crop. For questions or remarks please feel free to contact us.

Botrytis Control

Botrytis in flower buds is the same Botrytis causing flower buds to fall over. Falling over of flower buds in peonies is  an important disease every year. Although Botrytis is spreading fast during wet and warm weather, most problems are caused during cold and wet weather,  just before the flowering time. The flowers will not mature and are in a vulnerable stage too long. In this stage the mould will grow from the small leaf under the flower into the flower bud. When the weather turns warm and humid, the flower buds will fall over just before flowering time.
By spraying preventively the development of flower bud Botrytis can be stopped. Teldor Switch and Collis are strong products for the flowering, and this year Luna Privilege and Signum  have also been admitted. Use a fluid to make sure the product is applied well around the flower bud.

Botrytis in the crop

Common Swift Moth

Common Swift Moth

This year the common swift has been very active. The first moths have been spotted in the greenhouses, and they will show earlier in the fields this year than normal. The moths have flown out if the empty shells can be seen at the soil around the peony plants.

Common Swift Moth

The moths will lay eggs immediately,  from which the larva will grow. About 3 weeks after the first flight of moths the larva will hatch. For control it is important to start with Botanigard 3 weeks after the first flight of moths.

Advice: 1,5 kg Botanigard WP, after that repeat 2 times using intervals of 10-14 days. It is very important that Botanigard is applied to a moist soil and watered after application sufficiently. This because the product needs to be well soaked into the upper layer of the soil. Botanigard is available in fluid and powder. The powder (Botanigard WP) will obtain admission for the outside growth of peonies. The dosage of Botanigard fluid is 3 liter/ha. The dosage of Botanigard WP (powder) is 1,5 kg/ha.

Picture bank expanded with shortage diseases

The picture bank diseases, pests and weeds has been expanded with a new category. Shortage diseases in nursery stock:

Weed Control

At the moment products are used from which it is assumed that they will not cause damage. These products have not been used very long and not much experience has been achieved. Try to control weeds under a spray hood as much as possible. The most important problem is the accumulation of certain products. Peonies are being grown in the same spot for an extended period of time and every year the same products are being sprayed. It could be that the effect of some products will not be the same after a few years. Try variation in products.


Nitrogen is the element which is absorbed the most and the most easily by the plant. At strong growth like in the first weeks the plant needs a lot of nitrogen. With a shortage of nitrogen the leaves will turn light green, have less growth in length, plant is flowering too early and is sensitive for fungal diseases. More nitrogen allows for greater flowers.

Phosphate has a good effect on the formation of the main root system. A couple weeks before flowering phosphate in association with kali has a positive effect on the flower, they become fuller and bigger. That's why we advice to give extra phosphate and kali for the growth. With a lack of phosphate the leaves will stay smaller and the flowers will be more pale. Also there is a possibility of red / purple coloring of the leaves. (at low temperatures there can appear deficiency symptoms. Excess symptons are not likely to appear because phosphate is easy to bind to the ground particles. When applying too much phosphate it causes the plant to not take in magnesium anymore.

Kali takes care of the firmness of the leaves and the stem. Together with phosphate it will make the flowerbuds bigger. When enough kali is applied the plant can defend itself better against bacteria and fungi. With a lack of kali the edges of the leaves will turn yellow, starting with the older leaves at the bottom. The leaves will also become smaller and the stems will be thinner. Too much kali will give salt damage and the plant will grow slower. At a high dosis the plant will absorb less calcium and magnesium.
Magnesium gives the plant a healty and fresh green appearance. It also increases the strength of the celwall. It is a building stone for various enzymes. With a lack of magnesium the leaves turn yellow while the leaf veins will stay green. There is almost no excess possible.

Calcium is used by the plant for the solidity and the build-up of cells. It is the backbone of the plant. Calcium is very important for the water balance of the plant and is indispensable at high temperatures. At high temperatures the plant will eveporate a lot and has to take in more water. A shortage of calcium will arise at a too rapid growth and a too high humidity. Because of this the plant can evaporate to litlle or not at all. If a plant can not evaporate then it will also not take in any water or nutrition. With a lack of calcium the young leaves will die and the plant will be more sensitive to fungal attack. In the greenhouse there has to be given extra calcium.

Trace elements does not get enough attention in the cultivation, trace elements are the vitamins and minerals for the plant. Trace elements are: Fe = Iron, Mn = Manganese, B = Borium, Zn = Zinc, Cu = Copper and Mo = Molybdenum. Al these elements have an important function and are also the building blocks op the plant. Trace elements are important for the water balance, cell division and metabolism for the plant. The trace elements are absorbed by the plant via its roots so it is important to have enough of them. There are almost no trace elements in the nutrition that we buy so it is extra important to give extra during every feeding.

Measurement = Knowledge 
Take at regular intervals a soil/leaf sample so that you will get a better view on the needs of the plant.

Normal fertilizer applications kg/ha for peonies on yearly base
(at normal soil levels)N- needs: 150 kg/ha
Phosphate, kg P2O5: 100 kg/ha
Kali, kg K2O: 225 kg/ha
Magnesium, kg MgO:100 kg/ha
Shortly before flowering fertilize correctively with:
Nitrogen by leaf spraying for larger flower buds
Magnesium by leaf spraying for color
Calcium by leaf spraying for hardness
Trace elements (manganese and iron) for color

After flowering, fertilize for the next season.
* Straw half of potassium
* Nitrogen minimal 50 kg
* Magnesium

Make sure that there is enough water for the plant during this period. Drought will cause damage to next years flowerproduction. An active soil life is very important. Moist soil and organic content are very important to further take in the fertilizers mentioned above.

Organic fertilizers after flowering!

After flowering it is possible to serve fertilizers in various ways. DCM sells slow working organic fertilizers work perfectly for the cultivation of peonies. After flowering there is a need for nitrogen and kalium for production and the growth of the plants for next year. Fertilizing the plants can be done in various ways. One way is to apply the combined fertilizer DCM Mix 6 (6-3-18+3MgO) or apply the elements seperate from each other. When applying the elements seperate is the combination of Vivikali with regular nitrogen well known. The advantage of Vivikali over for example patentkali is the much lower salinity. That means that this fertilizer is much softer for the roots. This is very important in a period of extreme drought. Vivikali also contains trace elements, hormones and increases the soil life.The dosage of Vivikali is normally between 400 and 600 kg per ha. Because of the dry circumstances the plant will not take in all of the trace elements. A leaf fertilizer is a good solutions to keep the plant in a good condition.


Free-living nematodes: The nematodes appear on sand soil and light sulfur. Free-living nematodes have a lot of host plants. Economicly seen are the free-living nematodes the most important cause of problems. All free-living nematodes are able to carry over the 
tobacco rattle virus.

Root knot nematodes: when buying or processing be alert on attacks of root knot nematodes. Strong branched roots or visible nodules are signs. A warmwater treatment will resolve this issue.

Leaf nematodes: A deterioration of nematodes can clearly be seen at the deformity of the leaf. The leaves are grown half round and the tissue looks deformed. Sometimes the young growpoints can  dry out.

At the same time drying out of the flower buds can appear. This can be known by spoiled flower leaves surrounded by healthy top flower leaves. The flower buds can dry out in every stage. Sometimes the flower bud will open up but the flower will be deformed.

For spreading in the plants the nematodes need water. The nematodes move to other parts of the plant by means of water left on the leaves after watering the plants or during high humidity. Spreading also occurs during working with and maintenance of the plants. Because spreading takes place when the leaves are wet, do not walk or spray between the plants but from the paths between the rows of plants. The nematode will actually only do damage in the season after the infection. Nevertheless the infection can be detected in the first year. The leaves will show blue spots, fixed inside the veins. After a rain shower this will spread to the next spot in between the veins. During the winter nematodes are on wilted leaves on the ground and in the young grow points of the peonies. In the spring the nematodes will move with the growing plants or they will move up the plants using water. They feed on the plants. Doing this they cause toxic material to enter the cells. This causes deformed growing points, drying out of flower buds and total retarding of the growth. Nematodes can also lift on weed (seed) and infect the parcel.


  • Keep parcel free of weeds.
  • Remove the dried out flower buds.
  • Spray with Vertimec Gold 3 times at night, when the leaves are wet with dew, because then the nematodes will be at outside of the leaves.
  • Cut back the plants around the middle of August and discard the plant rests. Only do this during dry weather.


Tobacco rattle virus
The virus is spread by free living nematodes in the soil. The damage is usually limited to spots. Often healthy shoots appear next to damaged shoots. The virus will spread during dividing of the plants. The virus appears in a wide variety of host plants, like flower bulb varieties and weeds, among others Stellaria, Polygonna and Shepherd’s Purse. The virus can also be spread from a beech hedge.


  • The leaves have yellow spots, often circular, single or more circles and wave lines
  • On the leaves and sometimes also on the stems brown to black stripes and spots
  • Sometimes compact growth, leaves with bubbles, squeezed together
  • The virus can also be present and cannot be detected on the leaves, e.g. in peonies


Precautions organic material in the form of compost can lower the danger of infection.

  • Healthy plant material (go see the plants before you buy them)
  • Control weeds, especially root weeds, because these are host plants of nematodes
  • Discard diseased plants
  • Do not grow plants on soil that is known to be infected by the tobacco rattle virus
  • Steam the soil

Cucumber mosaic virus (CMV) can be spread by a large number of leaf aphids, among which the green peach aphid. Leaf aphids can take up the virus by sucking on the foliage of a diseased plant for only a few seconds. When after this they visit a healthy plant, the virus can be transferred immediately. Spreading of the virus will especially occur to the plants in the direct surroundings. The virus will spread during dividing up the plants. Cucumber mosaic virus has a very wide range of host plants among which weeds like: Stellaria, small ragwort, white and purple Lamium, button herb and black Solanum.


  • The leaves have light green to yellow circles, figures and spots on the leaf
  • Often a decrease of growth and misshapen leaves


  • Healthy plant material (go see the plants before you buy)
  • Weed control
  • Discard diseased plants
  • Spray against leaf aphids

Tortricidae moth (large apple moth)
Large apple moths nestle themselves in between the leaves. This makes the leaves roll up. In peonies this small fast moving black larvae eats to the flower bud of the plant. The larvae is not only hard to spot but also causes damage to the flower bud immediately. Regular control is necessary. Apple moths can be controlled with Decis, Runner, Turex and Xen Tari.

Green Works Care™

After extensive testing and research together with various institutions in The Netherlands and abroad we introduce Green Works™ Care for peonies.
The difference between a warm water treatments and Greenworks Care™ became very clear after our tests, read the benefits of Greenworks Care™ below.


  • No damage caused by warm water treatments
  • Because the treatment is carried out in-house the plants are less dehydrated
  • Special preventive treatment against root knot nematodes and leaf nematodes
  • Plants retain more content and vigor
  • Plant grows better in the first year
  • Blooming more in the second and third year


When interested or if you have any questions please contact: 

Check out the Peony assortment per variety: