Chilli Thrips the Roses' Enemy - The West's Sabrina Hahn
Chilli Thrips are continuing to wreak havoc on rose bushes (and other plants) around Perth. Gerberas are often companion plants of roses. Given time, these thrips will also affect gerbera plants.
Sabrina Hahn wrote a comprehensive article in The West's Gardening section on Friday 8 April 2022 and made several interesting points.
Chilli thrips are very difficult to see with the naked eye (2mm long) - you need a magnifying glass to see them properly.
They are active in spring, summer and autumn with a life cycle of several weeks. The adult lays eggs in the buds or inside the leaves. When these hatch, the larvae feed on the underside of the leaves. They then fall to the ground, where they develop into pupa and later the winged adult. So basically they are are all over the plant and in the soil surrounding it.
Repeated attacks on new growth can severely affect roses to a point where they require constant pruning of the new growth.
Management takes commitment and perseverance with severe infestations needing treatment every 7-10 days to break the life cycle.
All pruning tools should be cleaned between roses.
Do not put cuttings into compost or leave them on the ground - bag before binning.
There are several organic chemical options but they require repeated applications - OCP eco-oil, Natrasoap, Insecticidal Soap Spray, Beat-a-Bug natural pyrethrum, Yates Nature's Way Vegie & Herb Spray, Searles Ecofend Natural Solutions mite and insect spray, Hortico Insact Killer for tomatoes and vegetables, Sharp Shooter Natural Pyrethrum.
More systemic sprays have a longer term affect on the infected plant but a detrimental effect on bees and other pollinating insects.