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Gladiolus thrips can cause a mottling on foliage and flowers of gladiolus.
Gladiolus thrips (Thrips simplex) on gladiolus
Gladiolus thrips are small, narrow 2mm long, brownish-black insects that suck sap from gladiolus and some other plants including crocus, freesia, iris and lilies. Other species of thrips are unlikely to affect these plants.
White flecks on foliage and flowers of host plants. In heaver attacks, flower petals turn brown and buds fail to open. Rough, grey-brown patches form on the surface of infested corms.
When storing corms from affected plants cut down and dispose of the top growth (either by burning or council green waste) before the corm is fully dried to reduce the number of overwintering thrips, reducing the likelihood of infestation in the following season.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
Adult gladiolus thrips are 2mm in length, brownish-black and have narrow, elongate bodies. Adults can lay up to 100 eggs at a rate of one or two per day. These are often deposited on the younger leaves or in flower buds of host plants. The immature stages, known as nymphs, are pale yellow. The nymphs have three stages of development.
The first two stages, like the adults, feed by sucking sap and are entirely wingless. ‘Wing buds’ develop on the third stage which does not feed and is known as a pre-pupal stage. The pre-pupal and pupal stages take place in the soil and in sheltered places on the host plant. Wings are not fully formed until the adult thrips emerge.
Gladiolus thrips usually has two or three generations a year but may have more during hot summers. The thrips overwinter concealed on stored corms and can even continue to reproduce as long as the temperature remains above 10°C (50°F).
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Chemicals: using a sprayer Chemicals: using safely and effectively
Glasshouse red spider mite
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