Echinacea; Black, Sooty Rosemary
Answered by: Inge Poot
Question from: Jeff Hillyer
Posted on: April 5, 1998

I am the Botany Greenhouse Manager at Western Illinois University and have a professor interested in using Echinacea angustifolia for agroforestry. Could send me info on this plant; such as, ethrel treatment, other germination requirements, growing on and harvesting and handling the harvested plant material.

Echinacea needs to be stratified at 41 degrees Fahrenheit for 4-10 weeks and then sown in a sterile sandy potting mix, by pressing seed into surface and barely covering them. E. angustifolia benefits from a treatment with Ethrel as well which helps to quicken germination and make it more uniform. We offer an information sheet on the use of Ethrel (item no. D2281) which is available with an order of seeds.

Also have a question on rosemary. I have some with a black sooty substance covering the leaves and stems. I think it has something to do with mealybug. What can you tell me about this? Is there something I’m not doing right culturally? Is there something the plants can be treated with to clean them of this black stuff and not harm anyone that would use the plants?

Your rosemary must have something sucking its juices and leaving holes for the sap to seep out. Very likely you have a mealy bug or scale infestation. The sap is then colonized by a sooty mould -a fungus.

Spray with pyrethrum soap spray to kill the spider mites, scales or mealy bugs that are releasing the sap and when you have gotten rid of them the sooty mould will gradually disappear on its own. If your culprit are mealy bugs you will have to repeat the spray quite often and maybe even add a bit of alcohol to the solution to make sure the spray gets through the waxy covering of the bugs.

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