Is there a good way to get rid of spider mites from a Star Fruit tree? I've tried insecticidal soap with limited success. The soap also damages some of the older leaves. The tree's leaves are delicate, pubescent, and sensitive to movement. This presents a challenging problem when treating the mites with a liquid. The leaves fold up like a mimosa plant before I've had a chance to drench their undersides. Even if they didn't fold up, the down on the leaves make it difficult to coat their surfaces. A brush cannot be used without causing damage. The mites aren't a problem this time of year when the humidity is high and temperatures are low but I know they'll be back next year when the conditions are right. The tree is about 3.5' tall and is containerized. Any ideas?
I think you've already answered your own question. Others might disagree but in my opinion spider mites in the Northwest are mostly a cultural problem. Plants outside exposed to the rain and with the natural predatory mites around never seem to have a problem, it's when they are inside or under eaves or in too much sun that it is a problem. Being root bound can make it worse too. Can you raise the humidity and lower the temperatures?
No - the tree is indoors. It would be difficult to modify the environment to any great extent. Spraying with water over multiple sessions using less forceful sprays may work though. I'll try that if a solution doesn't present itself.
So I guess you don't have an outside area you could move it to for summer? Most of my houseplants move outside for the summer. I guess you already know about humidity trays, where you have a layer of gravel in an extra large saucer and you keep the gravel wet [but below the pot level]. You could try that. I like using the new ultra fine spray oils for a lot of pests but wouldn't recommend it for that plant because, like you say, the kind of leaf it is makes it really challenging. Always read and follow the directions on the label before using any pesticide. If you do a search on the web for predator mites there are companies who sell them. They are not cheap but that's about the only alternative I can think of.
Outside is not an option here. I've thought of predatory mites as well but they're expensive here too. Too bad there isn't some sort of trap for these nasties.
Spider mites indoors is much worse than they generally are outdoors. The problem is that many of the mites are misidentified as there is a false spider mite that seems to attack Carambola - Star Fruit in other locations than they will for us here where the spider mite is not considered a problem yet for our Star Fruit. Best control is predatory mites but growing this plant indoors is a real issue as I went through a spider mite outbreak with one of our Orchids that I brought in from a nursery that caused some real havoc including the death of the Orchid. This is not what you are going to want to read but you have to go after this insect or it will spread like wildfire onto other indoor plants you have. Citrus is a prime target for this insect. Insecticidal soaps do nothing for these insects indoors but wash them off and force them to move and they will be back soon when sprayed indoors. Repeated washings with jets of water alone can be successful if done outside and leaving the plant outside until the leaves dry. If that is not possible then you may have to use a chemical spray like I had to (I used Sevin) and it is better to spray for the insect outside and leave the plant outside until the leaves dry and then bring it back into the house. Jim
I think the problem with insecticidal soap is it only works against the juvenile and adult mites and not the eggs. Therefore it is effective in eradication only if applied in multiple sessions over a period of time. In this way the eggs are allowed to hatch and then dealt with by the soap before they've had a chance to grow and lay more eggs. I find the soap to be effective if used in this manner. It works even better if forceful sprays of water can be incorporated into the process; this physically removes many of the mites and their eggs in one go. (Of course this has to be done outside to avoid having them simply crawl back onto the plants.) I currently use Safer's insecticidal soap but I've been told the newer formulation End-All which contains pyrethrin is more effective.
I agree with Jim. I have two star fruit trees, a 6-foot and a 8 foot tree (in a greenhouse). Both trees have had infestations of spider mites in the past. Actually, I find spider mites not much of a problem to control. I take a garden hose with a common brass adjustable nozzel attached and adjust the nozzel to the beginnings of a cone shape spray. With a forceful water spray, I spray the tree from the top down, and then turn the nozzel up side down and spray from the bottom up. I do it three or four times. I repeat this proceedure for two or three days in a row. Has worked for me. If you can't take the tree outside, then spray it in the bathtub. - Millet
Looks like a healthy dose of patience and persistance will be required for this tree. I'll hose it down in the bathtub over an extended period when the mites show up again. Thanks.
What about spraying Lime Sulfur during its dormant season? This does control many types of mites. And of course there is a great Miticide called Monitor 480, its systemic through the roots, just mix and pour into your planter pots. Being your from Vancouver, the best place to get some Monitor480 is under the counter at most hydroponic grow stores. Just ask at the counter person for a bottle of "Stink" as its commonly known as. Growercental.com will have label rates. Just a suggestion. Jim.
I would stay away from using a systemic insectice on a plant the produces eatable fruit. The lime sulfur, I don't know how it would effect star fruit leaves. The leaves of star fruit are VERY delicate. I would certainly try it first, on a very small test area. For me water works 100% of the time. - Millet