Handling Mites in the Greenhouse

I am writing this message in response to Frank’s frustation with mites in his greenhouse.

Frank, I have had great success with Floramite. Sorry it is not working for you. I get great coverage and long residual time.

My only problem is that the plants in small pots are hard to spray on the under side. Instead, I mix a 5 gallon bucket of spray solution and then (with nitril gloves on both hands) I turn the 3 inch pots upside down and dip them in the bucket of Floramite solution. This gives a total kill and seems to last for more than a month in my house. On larger plants in taller pots, I simply spray the underside conventionally.

As a side note, I do use a surfactant (Indicate 5).

I would be very interested in what others are doing.


I love everything about my greenhouse except the spider mite problem. I’ve been able to keep them under control using Avid + Stirrup, but haven’t been able to eradicate them. I emailed Baldo Villegas for advice a few weeks ago. Here is an excerpt from his reply:

_"I am one of those that when I have a serious infestation of a pest I take care of it with a pesticide in order to reduce the inoculum/remnants of the pest (eggs) present. I might spray 2-3 times as recommended on the label until pest is under control and I monitor to make sure that they are under control.

"Afterwards I try to figure out why I had the problem and nonchemical means to stop it from happening. Monitoring is next to godliness when it comes to spider mites in the greenhouse. Properly placed misters to increase the humidity and “wash” the undersides of the leaves are important. This is how I do it and I have not sprayed a miticide for at least 5 years.

“At work my technician fumigates the greenhouses when they totally get out of control with Nicotine Sulfate. In fact she is supposed to have done it in the last few days at night as the County Pesticide Inspector wanted to come over and monitor the application. It had to be done at night when temperatures are under 85 degrees F in the greenhouses. Nicotine Sulfate is a permit pesticide and is restricted because of its high toxicity (Signal Word: Poison)!! After this she uses predatory mites which we used to get from Glenn Scriven in Riverside County. I am not sure where she is getting them now. We get monthly shipments of predatory mites which we use in our greenouses as prophylactic treatments.”

I wonder if it would help to fumigate the greenhouse with tobacco smoke?

I wrote an article in the newsletter a bit back about breeding roses in the greenhouse. I had asked around about mites before I got started. I have bred roses in my greenhouse 3 summers now, and used 3 different control combinations, which means that I haven’t really got a complete handle on any of these methods, but here it is for what it’s worth:

year 1) di-syston systemic granules in the pots and Isotox (containing the miticide Vendex), the miticide kelthane, and insecticidal soap. The soap was once a week, with the miticides added in rotation less often. I got complete control.

year 2) I used Avid, along with the soap, but only every other week or less. By the end of the season I had to use insecticidal soap more often along with Isotox to reestablish control, because the mites had become resistant to the Avid (I should have rotated it with another miticide, but they are all so expensive).

year 3: this year) I’m focusing on taking care of my seedlings, so I haven’t started to breed yet. I am only using water sprays every 2 to 3 sunny days, and I have had good control. If I can figure out how to continue the water sprays while I am pollinating, I may not go back to miticides again.

I am certainly not a professional on pest control, but I don’t think that mite eradication is possible. Water and insecticidal soap are remarkably effective for control, often better than miticides. The problem with water and soap (and contact miticides) is that you have to get the undersides of the leaves. I use a “Y” valve on the end of a short wand to direct water up under the leaves, and I always spray using an atomizer, which covers he whole leaf very well. One weird thing I have found out is that I can’t use my well water with insecticidal soap, as it is too hard, and the soap comes out as solution as “gunk.” For any of our members who are unfamiliar with greenhouses, I just want to mention that extreme measures for self-protection are needed whenever spraying in an enclosed area like a greenhouse: respirator, goggles, full clothing that can be quickly removed, etc… Obviously, the water spray is safe, but I usually end up drenched.

Spidermites have been especially bad this year in my garden. I have used Avid and Floramite without much success. Maybe a few drowned in the spray. However, in my greenhouse I have used Floramite with good results.