Lavender Issue

Asked August 18, 2020, 3:26 PM EDT

My Lavender plant has the bottom stems turning brown. I cut these away and notice some very small white bugs on the ground. I’ve also noticed a rabbit resting under the plant. Not sure why this vibrant plant just two ago has taken a turn for the worst. Can you help me figure out what I can do please. Thanks

Baltimore County Maryland

1 Response

Lavender does not get a lot of insect problems and we cannot say what the white bugs are that you are noticing. The rabbit resting under the foliage will not hurt the plant.

Lavender grows best in full sun in a well drained soil. Raised beds are a good choice. This plant does well in very dry areas of the country with soil pH that is neutral to slightly alkaline.

Lavender is beautiful but it just doesn't grow very well or for very long in Maryland. Lavender tends to be short lived in our area. Our climate is the main problem in that the plants need great drainage, especially in wet or severe winters and wet summers (which we are having). They also do not like our humidity.
They can be prone to root rots, a web blight https://extension.umd.edu/hgic/topics/rhizoctonia-web-blight and southern blight https://extension.umd.edu/hgic/topics/southern-blight, all disease issues.
If the site gets soggy, then lavender is not a good plant choice. The plants will eventually decline.

All you can do is check for southern blight. This fungus can attack probably all herbaceous perennials and is favored by hot weather.
It generally causes the top of the plant to collapse with quite visible fine white mycelia and mustard seed like fruiting bodies on the stem and at the base of the plants. Oxalic acid is released and girdles the tissue but does not kill the roots. The plants and fungus comes back. It can filter down into the mulch.

If you see this, we recommend that you remove the mulch and plants, including the top several inches of soil to help prevent more infection. Minimize the use of a deep mulch and keep away from the stems of the plants. Practice good sanitation and Do not compost material killed by southern blight.

Also, check the soil drainage and make sure it drains well otherwise the plant will be prone to root rots. Make sure mulch is thin and away from the base of the stems. Thin the plants to increase air circulation, remove fallen debris, and prune affected stems to help reduce the amount of moisture trapped and will promote faster drying of the planting bed. You may have to plant another type of plant that grows well in your site conditions taking into account mature height and width.

Here is a link from the U of Illinois with more information http://extension.illinois.edu/herbs/lavender.cfm

Marian