Laidback Gardener Tip of the Day

Bugs that Spread Plant Diseases

Spittlebug larvae live in a mass of bubbles commonly known as frog spit or snake spit.

Insects that feed on the sap or grate or eat the leaves of our plants sometimes have much more serious consequences: they may well be carrying an incurable plant disease that will cause more damage that the insect itself ever did. Plant viruses and their relatives, viroids and phytoplasmas, are mostly transmitted by insects that inject them into plant tissues as they eat. However, there is no treatment for viruses in the home garden except to pull out and destroy the plant. This is why it is important to act quickly when a plant is attacked by any insect. Among the insects that transmit viruses are aphids, flea beetles, leafhoppers, whiteflies, thrips and spittlebugs (froghoppers).

Grass infected with a mosaic virus… but few plant viruses are this visible.

Viruses (and other related diseases) sometimes have visible symptoms: for example, a specific discoloration of the leaf (mosaic or marbling) or deformed foliage or flowers, but most often not… except the plant becomes weak and less productive. The two classic cases are strawberries and raspberries. Both are very productive for 2 or 3 years, then go so far downhill due to multiple viral infections that the only logical solution is to destroy them and start anew with “indexed” plants (plants confirmed to be free of viruses).

A good way of reducing the attacks of virus-carrying insects in the home garden is to maintain a good biodiversity in your plantings. Monocultures, where a single plant species is grown over a large area, attract and retain predatory insects of the crop being grown. When plants are grown in mixed plantings, though, these insects have a harder time finding their favorite host and your plants are therefore less often infested with debilitating diseases.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

1 comment on “Bugs that Spread Plant Diseases

  1. If I can add just a light bit of humor that the real world authenticity of your post inspired–everybody talks and writes with so much romantic revery about the garden–but as you demonstrated in this post–it is a real war out there–so on to the humor–facts of life step into the garden–could be a good satirical movie with lots of laughs, no?

    Thanks for the post and love your laidback gardener photo!

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