House Plant Pests and Diseases – Part 1
More and more people are discovering that growing indoor plants is a very satisfying and rewarding hobby. And because the homes in which we now live are lighter, warmer and more or less drought free, than they used to be, there is less chance of house plants suffering from dramatic changes in temperature throughout the course of the day, or night. So a whole new range of indoor plants from across the world can now be successfully grown indoors.
This article focuses on common pests and diseases found on indoor plants.
Ants are not necessarily harmful themselves, but they can carry aphids to the softer parts of the plant. Ants are attracted to the honeydew deposited by green fly and can carry these pests from plant to plant. Your local garden centre will have a pesticide in dust form, to control ants on house plants.
Aphid or greenfly is a familiar garden pest that can move indoors. These attack the plant by sucking sap from it and depositing sticky honeydew, which in turn can attract fungus. Leaves, stems and flowers may appear distorted. The aphid’s are not only green, but can also be grey, black or yellow. As soon as you spot this pest spray the plant with pyrethrum or permethrin. If neither of these can be obtained quickly, then use soapy water and repeat spray regularly. Also soak the soil with any of the above. Remove and discard distorted growths.
Leaf Miners often attack Chrysanthemums and Cinerarias by tunnelling through leaves. They leave tell-tale wandering narrow lines, or ‘mines’ and the grubs can usually be spotted if the leaves are examined closely. Remove any affected leaves and spray the plant with a pesticide suitable for grubs.
Mealy Bugs. These are little oval bugs, covered with a white fluffy substance, they are usually found under leaves or on leaf joints. Almost any plant can be attacked causing the plant to wilt and leaves to yellow. Pick of all the bugs that you can with a tooth pick, any nests can be wiped away with soft cotton wool or a fine paintbrush soaked with methylated spirits. Spray all top growth with a suitable pesticide and examine plants regularly for reinfestation.
Red Spider Mites. Distorted and dry looking leaves are a common sign that these tiny mites are present. Look under the leaves for a fine white web. The red or pink pests are difficult to see without a magnifying glass. Prompt action is needed to stop the infestation from spreading. Badly affected leaves should be cut away, then spray the plant with a liquid derris. Repeat after 5 days and again after 10 days.
Scale Insects. These creatures are a yellowish brown colour and can be difficult to detect. They cling to the underside of leaves and are covered with a hard waxy cover. They suck sap from the plant causing it to wither. They also secrete honeydew which in turn can attract ants. Remove by scraping with a tooth pick or the top of a biro pen. Then wash the leaves with soapy water and apply a pesticide.
Thrips or thunder flies suck sap from soft foliage. They move about by jumping and leave black dots on the leaves or white spots on flowers. Remove damaged foliage and spray with liquid derris or suitable pesticide.
Part two covers Weevils, White Flies and Worms, and includes common house plant diseases.