Are white or black flies swarming around your painstakingly tended tomatoes? That's no reason to fret. Find out here how you can scare away the pests instead - with natural means and in the long term.
Fight whiteflies without chemicals
They spare tomato plants neither in the field nor in the greenhouse. Whiteflies (Trialeurodes vaporariorum) are 1-2 mm small, floury insects that multiply explosively in summer. Females lay hundreds of their white eggs on the underside of leaves. Tiny larvae hatch from this and feast on the leaves. If the infestation pressure is high, the plant dies. How to deal with the pests:
- protect the tomato plants in the bed with a close-meshed insect net
- plant marigolds and nasturtium as underplanting
- Spread beneficial insects in the greenhouse, such as parasitic wasps, (22.99€) ladybirds or the assassin bugs Macrolophus caliginosus
- Hang yellow boards
- shake the plants to catch the rising swarm of flies with the vacuum cleaner
- Do not plant tomatoes too closely, no more than 2 copies per square meter
To prevent this, make a broth from oak leaves and nettle leaves and sprinkle over the bed soil. Also, incorporate neem seeds into the soil, a natural pest control agent.
Repel black flies from tomatoes
If black flies infest your tomato plants, it is mostly thrips (Thysanoptera), also called thunderflies. Silvery blisters on the upper side of the leaves and black droppings on the undersides indicate an infestation by the 1-2 mm small insects. Their larvae develop in the root area and cause considerable damage there. How to ward off the plague:
- hang blue glue boards to catch the adult flies
- Remove and destroy infected plant parts
- apply lacewing larvae or predatory mites in the greenhouse
- brown soil attracts thrips, so mulch with light-colored straw
- fertilizing with nettle manure prevents thunderflies
- Repot tomatoes in tub culture into fresh, disinfected substrate
tips and tricks
Potting soil is often infected with insect eggs. The substrate is disinfected beforehand so that fly larvae do not attack tomato seedlings during sowing. Put it in an ovenproof dish with the lid on for 30 minutes in the oven at 180 degrees or in the microwave for 10 minutes at 800 watts.