Red spider
| Red spider | ||||||||||||
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Red spider |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Panonychus ulmi | ||||||||||||
| ( Koch , 1836) |
The red spider or fruit tree spider mite ( Panonychus ulmi ) belongs to the spider mites and causes damage to grapevines , apples , pears , plums , gooseberries and currants, among other things . The red velvet mite from the genus Trombidium , which is often referred to colloquially as the red spider, must be distinguished from it.
biology
The species overwinters in the egg stage on fruit trees. The majority of the spider mites hatch in spring and sex animals and summer eggs appear from May / June. The females are about half a millimeter tall, brick-red and have characteristic white bristles on their backs. Around 20–40 eggs are laid per female, around five to seven generations are formed each year. In the grapevine, the females overwinter in the area of the winter buds.
Damage
Dark leaf tips are initially visible on grapevines in spring after budding. There are also dark stitch marks on the unfolded leaves. The leaves curve upwards, stay small and fall off. The drive remains short. In summer the leaves turn bronze-brown.
Combat
The use of chemical-synthetic agents can be kept low with suitable control. The red spider has numerous natural opponents such as predatory mites , predatory bugs , lacewings and ladybugs . The targeted use of the predatory mite Typhlodromus pyri has proven effective for biological control . Since P. ulmi is also increasingly found in greenhouses and garden centers in greenhouses, the predatory mite Amblyseius californicus can also be used, whereas the predatory mite Phytoseiulus persimilis can not achieve sufficient control success. In exceptional cases it may be necessary to spray with phosphoric acid esters or with specific acaricides after the animals have migrated into the herd. The best control results are achieved when the majority of the mites hatched from the winter eggs and no summer eggs have been laid by the first generation of mites.
Combating indoor plants with predatory mites is often unsuccessful because they require unusually high levels of humidity. The use of chemical pesticides, on the other hand, can often damage the plant more than the mites. In the case of an infestation on, for example, Ficus religiosa , only the radical reduction of the plant to a stump that can be sprout again helps.
Web links
- Red Spider - Rebschutzdienst Lower Austria
- Panonychus ulmi at Fauna Europaea. Retrieved May 4, 2011