Aster Yellows
Growth turns yellow or an odd red-purple, twisted and stunted, and the flowers come out wrong rather than merely faded. Petals stay green and leafy, or a coneflower throws small extra flower heads straight out of its old cone. Carrot roots go thin, hairy and bitter.
Disease checklist
Four things to look for. If most of them match what you are holding, you are in the right place.
What gets rid of it
Gentlest option first. For most backyard cases the first one is enough, so try these in order and stop as soon as it works. If you do spray something, the product label tells you how — please read the notice further down.
1Remove infected plants
There is no cure. Dig them out and destroy them so they stop being a source.
Try this first2Clear perennial weeds
Weeds around the garden carry it over and feed the leafhoppers, so keep the edges cut.
3Row cover on carrots
Cover carrot beds early in the season to keep aster leafhoppers off the crop.
insect netting row cover4Replant with less susceptible plants
In a bed that keeps getting it, use plants that shrug it off such as geranium and impatiens.
5Do not save infected garlic
Never replant cloves from a bulb that showed streaking or dieback.
6Skip insecticide in a home garden
Trying to spray aster leafhoppers out of a garden generally does not work and does not protect the crop.
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Which plants get aster yellows
Every plant we cover that gets aster yellows, grouped by type — tap any one to open its page. A note beside a plant came from that plant’s own entry, because the same disease can be a minor nuisance on one plant and a serious problem on another. Plenty of plants we do not cover get it too.
perennials4
biennial1
annuals4
Plant families hit hardest
Related plants often share the same problems, so if one plant in a family has it, check the others. The largest group here is Asteraceae, with 6 of the 11 affected plants.
- Asteraceae6 plants
- Apiaceae2 plants
When to treat
Pull suspicious plants the day you spot them, because leafhoppers pick the phytoplasma up from them and carry it down the bed.
Timing only — the label is the law
This page tells you when to watch for aster yellows and when treating is worth considering. It is not a recommendation to apply any particular product. Read and follow the product label before you spray — under federal law the label is the legal instruction, and using a pesticide against it is illegal.
- Check the pre-harvest interval. Every product that’s cleared for an edible crop sets a minimum number of days between spraying and picking. Find it on the label before you spray anything you intend to eat.
- Check the re-entry interval before you or anyone else works in the treated area again, and use the protective equipment the label names.
- Confirm the product is registered for your crop in your state. This page groups many different crops together, and a product legal on one of them is not legal on all of them — state registrations differ too. Your state pesticide agency or local extension office can confirm both.
- Rates and mixing instructions come from the label, never from us. We don’t publish them because they differ by product and formulation.
Other problems on the same plants
If a plant gets aster yellows, these are the problems it most often gets as well, so they are worth checking for while you are out there. They tend to appear together; one does not cause another.