A Happy Seedling
Green Thumb
Posts: 303
Joined: Fri Jan 30, 2015 6:41 pm
Location: USDA Hardiness Zone 7a

Spider mites on hibiscus

Okay, so I have a hibiscus. I believe it is tropical. I got it from a nursery near me. It bloomed prolifically over summer, spring, and fall, and before the frosts came I brought it inside.

It was doing fine until, two weeks ago, I noticed a few small black mite-size bugs on the plant. I sprayed with soapy water; they have not come back. Then I saw some beige and white dots/mites covering my very young buds; they did not die so easily when sprayed, but they did not spread and are still isolated to one area of the plant. (My hibiscus actually has three stems, maybe three plants?) Now, I noticed A LOT of tiny white mites ALL OVER my hibiscus, covering young growth, and leaves, but not mature flowers. Buds, though, are also covered. There are spider webs stretching between leaves, but no spiders, and I suspect spider mites.

Could you guys help me confirm my ID and treat this heavy infestation?
Diagnostic information:
Blossom color: Light yellow
Blossom diameter: Maybe 5 inches
Leaves: Not particularly glossy
Mite color: White
Leaf health before mites: Good, a few leaves yellowing and dropping
Leaf health after mites: Speckling on leaves, speckles are brown or dark green with yellow rims, sometimes streaks instead of speckles. Increased number of yellowing and dropping leaves; some leaves just straight-out dry up and fall.

Any help?
~AHS
When I wait 3 months for my mango seedling to sprout, and then it damps off.
:evil:

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applestar
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Posts: 27486
Joined: Thu May 01, 2008 11:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M

Re: Spider mites on hibiscus

It does sound like mites. I imagine with the rapid drop in temperature recently, your heater has been cranking away and depleting the humidity in the house.

If you can, it will help to put the plant in the shower once a week and treat it to a nice tepid shower (shouldn't feel warm to you). Cover the top of the pot/soil with plastic bag.

If this isn't feasible (I have too many plants and some are too big to lug upstairs), thoroughly mist with hand or pump sprayer every morning until dripping wet (put something under the plant to protect surfaces that can't take wetting down.) I use filtered water because minerals in the tap water leaves white residue on the leaves as well as any other surfaces.

If you have access to willow, you could make a decoction/boiled tea of bark and twigs -- Willow water has been shown to improve plant health and immune system.

I'll leave the mite eradication advice to others since I have not had much success. Best results for me have been when, nearing end of winter and spring is arriving, I can put the plants outside and the outside Garden Patrol takes over. I'm working on NOT sabotaging importing the mite predators with the plants when I bring them in, and NOT killing off the predators by treating against mites. So far only a partial success.
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.

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digitS'
Super Green Thumb
Posts: 3460
Joined: Sun Sep 26, 2010 5:10 pm
Location: ID/Wa! border

Re: Spider mites on hibiscus

I have never seen white spider mites.

They can be a huge problem in my dahlia garden during the heat of summer. I have noticed that the evergreens in the neighborhood can also have multitudes. They are red mites but so tiny, they take require close inspection.

The webbing is a give-away to the minuscule critters. However, the mites are fairly easy to kill with insecticidal soap. The webbing remains.

I say that they die with the soap spray but I have to hit them with it. That's difficult because the mites are usually on the underside of the leaves or between flower petals.

If you can see these pests how about removing them with your digitS'? Could you give your plant a good rundown?

Steve
But relax and do not rue:

For the Other, too 'tis You! ~ Peter Rosegger

imafan26
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Posts: 11121
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Spider mites on hibiscus

spider mites are usually a problem where air circulation is not that good and during the hot dry days of summer. Usually a good rain knocks them off. If you can get them outside or even in a garage and jet the bottom of the leaves especially with water to knock the spiders off. If the plant is small enough you can soak the top of the plant in bucket of water + oil (horticultural oil or neem) 1 tbl per gallon of water for about 10 minutes. Cover the pot with a plastic bag and tape it up to keep the soil from falling out. The oil will help to smother them.

You can also use Bayer disease, insect, and mite control but only on ornamentals. It contains imodicloprid and is a short acting systemic that lasts about 30 days.
Merit or Bayer tree and shrub control also has imodicloprid but lasts up to a year. It is also very harmful to bees and beneficial insects so I only use the shortest acting and only when other controls don't work and I disbud while it is active so that bees are not harmed. Mite control does list that it can be used on houseplants. Bayer tree and shrub for outdoor use only. When I have to use it I isolate the plant. My hibiscus is in a pot and I treat it where the run off will not get into the ground or other plants nearby. I use it for erineum mites and I only need to cover April-June when they are the most active or the hibiscus will have only stunted deformed leaves.

http://www.bayeradvanced.com/~/media/Ba ... %20oz.ashx

Soaps don't work that well and oil only works if you get good coverage. For spider mites you really need a miticide since they are arachnids not soft-bodied insects.

Outdoors, predatory mites will eventually control the spider mites and rain takes care of the rest. It is a seasonal problem so I just regularly jet the leaves with water in summer to knock off the dust and insects. I only treat the erineum mites when the damage is severe. It is either that or get rid of the plant since it is an imported pest without good biological controls. The problem with using any insecticide is that it does not descriminate and harms the good bugs as well as the bad. You need to be diligent later on to make sure the area is sanitized; get better air circulation, and you hose off the leaves regularly. Otherwise there will be a resurgence in the problem or other insects will appear since their predators have been killed off.
Happy gardening in Hawaii. Gardens are where people grow.

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