Trouble for Fava Beans

Citrus Bud Mites Deform Lemons

Deformed lemon copy 72

This is the photo that was submitted to go with my SF Chronicle ( Golden Gate Gardener column today. How could they resist printing this wonderfully sculpted Eureka lemon? But resist they did, so I thought you'd like to see it here. The image was taken by Dagmar Zidek, whose lemon tree has the problem. 

This happens because some mites enter the flower buds and start sucking out the sap. The ovary of the flower is misshapen, so the fruit is, well, outlandish. Citrus bud mite is apparently particularly a problem near the coast in our area, just where we depend on lemons for most of our garden citrus. 

The goal, in managing the pest, is to kill it without killing too many of its predators, in particular predatory mites. You have to spray when the bud mites are active and not yet inside the buds, which is May and June, then again in September through November. Use a summer oil spray. Some summer oil formulations are still based on petroleum, but apparently studies showed that vegetable oils worked fine too, so now a lot of the newer ones are based on vegetable oils, like canola or soy. So keep your lemons looking like lemons by keeping this pest under control!

Or maybe you'd rather go for the Deformed Lemon Hall of Fame.  


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Pam Peirce

I assume that the juice of citrus mite infected lemons is fine to eat. If you use the peel, to make zest, for example, you could eat some mites. However, I think they are not present in smooth, convex portions of the peel, only deep in the crevices of the deformity.

Karine Yong

Are infected 'alien' lemons OK to use in cooking? I would think just the juice would be OK? Any comments? Was given some alien Myer lemons😊. Ok to use the juice?

Kyle B.

Can you eat the deformed lemons? Or will I like die or something?

Jane Veeder

Thanks for this article. I just discovered on my reliable Meyer lemon quite a number of new, barely fruits looking deformed and "multiple" like citrons even at less than an inch in diameter. I will look for the summer oils you mention. This tree is over 25 years old and has never had this problem before. I will be trying to figure out what makes these mites more of a threat - weather? change in amount of sun (a neighbor's pine tree keeps getting bigger and cutting off more of the afternoon sun), etc.

Pam Peirce

Summer oil acts by smothering the insects, including the eggs. The reason it is called "summer" oil is that petroleum oils containing sulfur would damage or kill leaves, so can only be sprayed on dormant woody plants. Summer oils based on petroleum are formulated to be free of sulfur, and there isn't any sulfur in the various botanical oils used in the sprays, so they can be sprayed on leaves.
Horticultural oil sprays typically contain an oil and a sticker-spreader. I suppose one could find the sticker-spreader sold separately, but you'd need to figure out how much oil and sticker-spreader to use, which I have always thought not worth the trouble to figure out. If you search around in nurseries or on the web, you can probably find a ready-made product that you'd want to use. I don't know why you'd object to canola oil in the tiny amounts it would exist in an oil spray, but if you do, I have seen summer oils based on soy or even on jojoba, a desert plant that is the source of an oil often used in shampoos and the like.
You could also use neem oil. It is the oil of neem seeds, from a tree native to India. This oil contains some of the botanical toxin the tree produces that is so unappealing to insects that they often stop feeding. If they do keep eating, it is toxic to them. It lasts only briefly in the environment. Many gardeners use neem oil, but often any summer oil would probably do the job they are trying to do.
In any case, oil sprays are all generally sold as concentrates, so you'd dilute the product with water before you spray. If you made your own, you'd need, In addition to figuring out the proper proportion of ingredients, to figure out the proper dilution of what you made. While I'm sure some gardeners have figured this stuff out, I haven't, and would rather just buy a bottle of pre-formulated product every once in a while.


What does "summer oil" do? What is typically in it besides petroleum products? What makes it effective? I would like to make my own free of petroleum or canola.

Pam Peirce

Hi Rebekah, I don't think there is any reason not to use the juice of the lemon that mites have infested. They attack the flower, causing the ovary to develop poorly. There probably aren't very many actual mites in the mature lemon, since they don't lile the big, tough lemon as well as the tender flower. If there were any, they'd be in crevices in the peel, not the juice, so you might not want to use the peel in cooking. In any case, I don't think the mites would be harmful to eat. There is only the "yuck" factor to consider.


Hi all-

My lemons started looking a lot like this picture..........some are normal and some look so weird! this is the first year it has happened.....

That being said, are they still OK to use when they ripen, or should I just cut them off and focus on the 'normal' looking fruit? Does anyone know that answer? I would greatly appreciate some info......



wow indeed! Can't believe that Citrus bud mite can create such problems in flower buds.
I too believe that SF Chronicle should have published this one. It would be helpful in controlling this pest problem.

Thanks for sharing.

Kathryn Fairchild

In the print copy of this article you refer to another column written 2/15 about the rat gnawing problem. Can you direct me to that post because I missed it in the paper and can't find it on my own on your blog? I believe that must be what is causing our lemon trees to look "pruned", and I'd like to know what you wrote about it. We live on a canyon in Belmont. Thank you.

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