Curled leaves on roses are not a pretty sight. But they are much more than visual flaws – in many cases, the scroll wasp is to blame.
Curled leaves on roses – signs of an infestation
The rose sawflies are tiny insects that grow to a maximum of 4 mm in length. The pest lays its eggs on rose plants and affects both shrubs and climbing roses and flowers. The many small, white dots on the underside of the leaves can hardly be seen with the naked eye. However, when the wasp larvae hatch, you can see them. They are about 1 cm long and have a yellowish-white body with geometric designs. These small larvae eat the rose petals and can cause damage. After the larvae get the necessary nutrients, they fall to the ground and hibernate in the ground.
The life cycle of the pest determines the time of infestation
The life cycle of the rose sawfly also determines when you can first see the damage to the roses. The insects appear in spring and lay their eggs on the underside of leaves around the end of April. The larvae hatch shortly thereafter – in May – and help themselves to the fresh rose petals. The second generation hatches at the beginning of July – then one can speak of an infestation for the second time.
Are your roses losing leaves? You must do this!
Rose sawfly larvae only eat the top layer of leaves, releasing chemicals that can damage the leaves. This is first noticeable with brown spots on the leaves, then individual areas of the leaf become transparent. Since the top layer of leaves is missing, the leaves curl up, slowly dry up and fall off.
The plants stop growing and put their energy into leaf formation instead. Although it is very rare for a badly affected rose to die, it will be weakened. Growth has stopped, the flowering period is shorter and the rose looks sleepy and sick. That’s why you should remove the pests (without killing them) if they are infested. Fortunately, this task is very simple. You have to cut off the affected leaves and throw them away with the household waste. This should happen once a week during the active periods – May and July. Otherwise the pests will hide in the ground. You must then expect another infestation next year.
So that the pests also attack the neighboring plants, you can transplant the rose. The minimum distance to other rose plants in tubs or to outdoor plants is 2 meters.
Prevent curled leaves on roses: Rainfarn-Sud protects against the pests
Tansy is a poisonous plant that can protect the roses from the pests. You can make a brew yourself. For this purpose simply:
1. About 50g tansy – it is best to use dried leaves and flowers in a medium sized pot.
2. Pour 500 ml of lukewarm water over the leaves and flowers and bring to the boil over medium heat. Then simmer for about 30 minutes. Remove the pot from the stove and let cool.
3. Strain the liquid and then pour into a clean screw-top jar. Store in a cool, dark place for about 2 months.
4. If there are signs of an infestation, fill a spray bottle with 60 ml of decoction and 360 ml of water and wet the rose petals and shoots well. Wait about a week and then repeat the process if necessary.
Fight the rose sawfly with natural enemies
Birds are natural enemies of the pest. You can keep the number of sawflies to a minimum, protecting the plants. So make your garden as varied as possible. Birds don’t need feeding stations in the summer, but you can place bird baths near the roses. Tall shrubs and hedges provide hiding places and nesting sites for birds.
Another way to get rid of wasps is to regularly loosen the soil. In this way, the birds can also find the larvae in the ground much more quickly.