Spider mites usually attack hydrangea when the plants are overwintered indoors. The tiny little mites prefer dry air and can damage the hydrangea so badly that it even dies. Therefore, in the event of an infestation, rapid action is required.
Spider mites are very stubborn pests
The Pest
Spider mites are widespread pests with more than a thousand species worldwide, of which only two are important in our latitudes. These are the:
- Common spider mite (Tetranychus urticae)
- Fruit tree spider mite (Panonychus ulmi)
The approximately 0.5 millimeter large, oval mites are yellow-green, brown or bright red, especially in winter.
The bad image
Spider mites prefer to settle on the underside of hydrangea leaves. As a result, they are often only noticed when the leaves are covered with a fine white web in the event of severe infestation. The mites pierce the plant tissue to drink the sap. As a result, light green spots become visible on the upper side of the leaf, which enlarge and coalesce over time. Hydrangea foliage turns yellow and dries up. The animals protect themselves with fine white webs that look very similar to spider webs.
prevention
If the hydrangea is attacked by spider mites in winter, it is usually too warm. The animals prefer dry air, so you should water the plants regularly even in winter. Make sure the hydrangea is in good condition before moving to winter storage. Healthy and strong plants have a natural protection against harmful insects.
Check the undersides of the leaves cyclically with a magnifying glass. The animals are so tiny that you often cannot see them with the naked eye. If the characteristic webs appear, the infestation is usually already well advanced.
combat
Proceed as follows to combat the pests:
- Shower infested plants with a strong jet.
- Since spider mites don't like moisture, repeat this procedure every few days.
- Lower the room temperature or keep the hydrangeas cooler.
Is this not enough:
- Cut off infested plant parts and dispose of with household waste or burn.
- Treat hydrangea with a special pesticide.
Since the mites are mostly on the underside of the leaves, it is important not only to wet the surface of the plant, but also to spray all the leaves thoroughly from below.
tips and tricks
A good prevention are plant protection sticks that are stuck into the ground. Over a period of months, they release an active ingredient that is absorbed by the hydrangea. As a result, the hydrangea is excellently protected against pest infestation.