Control pests in ornamental horticulture

Nematodes are used in ornamental horticulture both outdoors and in greenhouses. They can be applied via Dosatron fertilizer mixes, via drip irrigation and via overhead irrigation.

Our expert: Sabrina Sieger

I will be happy to advise you on the use of nematodes in ornamental plant cultivation.


Protected cultivation - fungus gnats, thrips, butterfly caterpillars, and root borers.

The main pests in protected ornamental cultivation are fungus gnats (Bradysia paupera), thrips (Frankliniella occidentalis) and butterfly caterpillars (e.g. Duponchelia fovealis, Opogona sacchari). Caterpillars that feed on above-ground plant parts are controlled with nemastar® (Steinernema carpocapsae). nemaplus® and nemaflor® are effective against thrips and fungus gnats, nematop® and nemaplus® against the small rootworm (Pharmacis lupulina).


The caterpillars feed on the above-ground plant parts and develop several generations per year. nemastar® should therefore be sprayed every 10-14 days, 4-5 times per season. The application rate is 125,000 - 250,000 nematodes per m² or 1 million nematodes per liter of spray broth. Ideally, plants should be sprayed in the evening hours until just before dripping. Air temperatures should be above 14 °C during the day.



California flower thrips (Frankliniella occidentalis) is one of the most dangerous greenhouse pests. It attacks almost all greenhouse plants and especially flowering ornamental plants. Direct damage is caused by sucking activity and resulting deformations, and indirect damage is caused by the spread of viruses.

For pupation, 95% of the penultimate nymphal stage (commonly referred to as the prepupa) migrates to a soil depth of 1.5 - 2 cm. The presence of predatory beneficial insects active above ground increases the proportion of prepupae migrating into the soil. Thrips spend 1/3 of their development in the soil.

This is also where the nematodes come into play. 125,000 - 250,000 nematodes are applied per m² with at least 100 ml of water. The application is done by drip irrigation or with a foliar application without wetting agent, so that the drops can roll off the leaves. The nematodes attack the thrips present in the soil, but hardly reproduce in them, so this application must be repeated every 10 days, because new thrips are constantly migrating into the soil.


Sciarid flies

The fungus gnat belongs to the family Sciaridae and is a common pest in ornamental plant cultivation.

Fungus gnats are very small black gnats, only about 3 mm in size. They are easily identified by their two long wings and sluggish, lurching flight. Their larvae are about 5 mm long, legless, slender, glassy translucent with a dark head.

Fungus gnats or fungus gnat larvae can be well controlled with nematodes of the species Steinernema feltiae. The nematodes must be applied into the top of the substrate. The dosage is based on 10,000 nematodes/m³ substrate or 500,000 nematodes per m². As a rule, it is recommended to repeat the treatment after 10 days. Preventive nematode use has proven particularly effective for poinsettia young plants.


Field crops - weevils, leather jacket larvae, root borers.

The main pest in field crops is mainly the black vine weevil, Otiorhynchus sulcatus. It is susceptible to nematop® or nematodes of the species Heterorhabditis bacteriophora. In addition to weevils, larvae of the genera Tipula paludosa and Tipula oleracea can also cause problems in field crops. They are well controlled with nemastar® or nematodes of the species Steinernema carpocapsae. Against the larvae of the common swift moth (Pharmacis lupulina), nematop® or nemaplus® can be used.



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