Like many other pests they zero in on certain plants particularly, maybe try planting only those they do not bother noticeably in those spots where favored items are hopeless.

For a free download that may be of interest...

Here is a link that might be useful: Extension Publications -- Root Weevil Control on Rhododendrons

Goheen on root weevils...

Here is a link that might be useful: Weevils

I have fought root weevils for 25 years. I have sprayed with Orthene, and for four years put nemotodes on everything. I can't think of one plant that they haven't attacked. A tree farmer said to spray with a solution of Fels-Naptha soap--guaranteed to destroy them. But they were as bad as ever. This year I think I have found the solution. In early spring when everything was beginning to grow I applied a drench of Orthinex. It appears to be working. The best results appear to be where the drench was applied to the bare ground. I will try it one more season before I claim success, but the damage is notably less this year.
I know I am doing great damage to the beneficial forms, but I see no alternative. I want flowers in my yard and there are very few that haven't been shredded.

I can't bring myself to use chemicals at this point. Where do I find the nematodes? A shotgun will suffice, or maybe a hand gernade! - Paul

Ican't help thinking there must be some sort of ecological imbalance in your garden to have such damage done by weevils. Populations must be incredibly high. Having gardened in this area for going on 40 years, I have never experienced much more than cosmetic disfigurement of various plants, mostly broadleaved evergreens, that could be attributed to weevils. An occasional root crown of a smaller perennial that was devoured by the larvae now and again (heucheras are rather prone to this), but other than that, nothing that was actually killed by weevil activity and certainly no stems of woody or semi-woody plants like roses eaten through.

Nematodes are as good a place to start as any and the timing is still OK but don't delay. Many area nurseries will offer various beneficials - typically nematodes are sold in a sponge that you soak in a bucket of water and apply as a soil drench. The nematodes work on the larvae only - you still need to get adult populations in check or the problem will persist. And it generally takes several seasons to achieve measurable control.

Drenching your ground with stinking toxic instecticides I would think would also kill the enjoyment of the flowers there. Are you going to do this every year, indefinitely? Hope you are using appropriate precautions to protect yourself during mixing and application. But then there is still the problem of post-application exposure...

I can't speak for irmas, but I do not have a huge problem. The only time I have any problem, is at very specific times. All of these things have to come together to cause any real damage. When I have a just rooted rose, or other tender plant(I root many plants at a time, and always have a few "babies" around), mainly near a covered area(which I just discovered was a link), and the wrong time of year. I do have the typical notching that they cause on some plants, but they never hurt anything. Except the D%@N rooted roses. They are weak, and still soft and green below the ground. The evil little things have ringed a few of my rose starts. They also attacked a recently transplanted rose, until it was established. Now I know, and I would not use a chemical to treat something unless it was killing MANY plants. Because it was below ground level, I think the larvae were doing the ringing, so a nematode drench monthly would be just the thing for a unestablished plant that shows signs of attack. Am I wrong? Why do they like covered areas though? could I discourage them by simulating whatever it is in an uncovered area? All input is welcome - Paul

Yes, the grubs gnaw on the crowns of target plants. Heucheras (as mentioned) and primroses that wilt despite watering may come off at the soil line when pulled on, revealing numerous weevil larvae inside the husk, like maggots, some of which may fall out as you are standing there holding the carcass.

At least they don't wriggle around.

Maybe shelter afforded by overhanging roofs and branches is what encourages them.

Nematodes are only effective when soil temperatures are hospitable for them (50-55F), the soil is moist and the weevil is in the correct stage of its life cycle to be affected by nematode populations. Generally the recommended times for application are May/June and again in late August/September (preferred). Make sure the soil is moist before application and follow the directions on the package carefully regarding application rates. Nematodes are expensive - you don't want to waste using them when they will not be active or effective.

I plan to repeat the drench next spring when the roots are starting to grow and the larva are active. I don't know if the Orthanex gets on the larva, or the roots take it up with moisture, thereby poisoning whatever eats them. Last year the Ilex was shredded, this year not a nip. I will not repeat that area next spring but cover some areas that I missed and I see some chewing. I hope this is all I need to do--it is discouraging to see such destruction and after all these years battling them I'm ready for desperate measures.

If the spoiled plants look like confetti, the leaves having had semicircular notches chewed out of them that is definitely weevils. The adults straddle the margins of the leaves and chew pieces out with their jaws. If the "shredding" has a different pattern then something else is happening.

If your garden is mostly out in the open it does seem unusual to have so much damage. If you have alot of evergreen trees and shrubs in close around/over the afflicted plants then not so unusual. Some deciduous trees also seem to host them, for example birches.

bboy, can you tell me why I find them in the house? I have just a couple of things with minimal damage outside this year (dwarf solomons seal, for one), have never found a houseplant notched, but I think I've flushed as many as 4 or 5 in the last month. Including 2 from this computer room. I don't think I move slow enough they could climb aboard or be on my shoes ( :) ) to be coming in on me, but I rarely find a spider or bug (everything screened) and I'm mystified about the weevils.

They are generally thought to be searching for moisture, as the only time you tend to see them indoors is in the middle of our dry summers and they also tend to be located around moisture sources - sinks, baths and showers, etc. How they get inside is a bit of a mystery. I have thought they might have hitched a ride on the coat of one of my dogs, but I suspect tiny cracks or gaps in walls, etc. are just as likely. They are harmless indoors, only living a few days if you don't find them first :-) This temporary invasion phenomenon is pretty common.

We get black vine weevil coming in here. Seems like it's more towards fall, but I've never taken notes. Haven't seen any yet this year.

Thanks....I'm so glad you didn't tie the intrusion to my housekeeping skills...

It is estimated that over 90 percent of the insects in a garden are beneficial insects or innocent bystanders. Even the ones you consider pests have a role in nature by turning weak, sick, diseased and over-fertilized plants into compost. When you use toxic chemicals, you kill all the insects and not just the few notching your leaves.

Given a choice between a healthy plant and an unhealthy plant, most pests will follow nature and try to eliminate the unhealthy plant.

If the plants under your eaves are attacked more frequently than others it could be that they are weak from drought stress or poor soil because of being too close to the foundation or pieces of concrete from the foundation under their roots.

Regardless of how important the rose plant is to you, you need to consider your own health, the health of the people and animals in your garden and the health of the world below your garden.

I can't think of any reason that a home garden should poison the environment.

I've had an organic garden for 22 years in this location. I have some weevils in one section but I leave the balance of the garden to take care of things. If a plant is too much of a problem, I jerk it out and put something different in. I did have some black aphids on an abutilon the other day but when I looked again, they were all gone.

The chemicals you're using require that you wear a mask and goggles and cover all of your skin. As you grow older and continue to associate with gardeners, you will observe a variety of ailments in common among those who used chemicals in their gardens. Cancer and Parkinson's Disease are the two I see most often.

A friend's late aunt was thought by her doctor(s) to have died from spraying her roses. Hope it was worth it.

I do not recommend the use of chemicals in the garden in most cases. I realize that damage is being done but feel that I have no choice. I do believe I have a rare situation--none of my gardening friends have the problem. They started showing up in around 1962 when an azalea died. I paid no attention to them at that time but noticed that over the years they were spreading to more areas of the yard. In the past few years they have just about taken over everything. And I have determined to stop them if I can.
As far as my health is concerned I don't worry. If Orthonex is handled properly there should be no trouble. At age 90, I think I'm safe.

You're doing very well to be using a computer at 90, Irma. My parents and in-laws didn't keep up with technology.

I have lost a lot of little mini-roses and a few other roses, but was ignorant of weevils so I will have to keep a look-out to see if I see any signs. I saved a lot of mini's that were little 3" sticks with no leaves by digging them up and putting them in pots where they would flourish and bloom.

I am an organic gardener and feel that by planting a wide variety of blooming plants and tolerating dandelion bloom, which if you study it is a succession of maybe 5-6+ different species set up by a Designer to provide food for bees and other beneficials, tolerating wasps, and not poisoning my environment, the harmful bugs can be kept in check. Sorry about your situation but my FIL who used pesticides at will got lymphoma and leukemia in his late 80's or early 90's and it really decreased his quality of life.

Down south here in the San Francisco Bay Area, I find that of the plants mentioned so far, only Heuchera are really susceptable to the grubs. It seems that they are much more prone in clay loam soils than in sandier soils, and I suspect that the Heucheras are somewhat stressed by my growing conditions, and would also prefer sandier, faster draining soils. The other problem plant types for me with weevils are Aeoniums and especially Echeverias. It pains me to catch them too late, when the weevils are alreay so far up the stems of these succulents, that there is no saving the plant. Again, it seems mainly linked to my stressing the plant by too much/too little water and a soil mix in long term containers that have not been refreshed often enough. So I would suspect that weevils further north are also a sign of not enough attention to what your plants prefer for healthiest growth. Not a lecture, just a personal observation. This is really emphasized for me when I talk to other gardeners locally with the same plants, and they never are troubled with weevils... Could it be just deserts for living in Berkeley?

a couple of free-ranging chickens will get rid of your weevils and any other garden pests in pretty short order.

I grow named tuberous begonias and weevils are the worst problem to deal with. I have found that the best and most effective measure is to use Provado weevil killer. It is just watered into the pots or baskets or surrounding soil and kills the maggots of the weevil. It is therefore harmless to insects and bees as it is not a spray.A word of caution - as it is persistant in the soil do not use on edible crops or put the used compost onto your re-cycling bin that would likely be used as a mulch around edibles.Hope this helps.
Hazel.

"I need THIS plant to grow right there." You want to go 'natural' and yet you aren't taking clues from nature. Nature is telling you 'right there' is not a good location for that plant. A small amount of a systemic insecticide would probably work if watered in around the plant.
You assume weevils ate the stem of the very young rose. Could it have been a slug?

I don't use insecticides either, but I don't grow roses. If bugs eat a plant to the point of having to drench it or the ground, with chemicals to keep it looking good, I don't grow it.

Some varieties of rhododendrons are more suseptible to weevils than others. I have read that it's flat leafed vs. curled leaf. Flat being the most suseptible. In some cases though, the cause is many branches touching the ground giving the adults many paths to the leaves. Given a single trunk the weevil damage is usually much less.

Last March I felt a little creepy when it appeared that a heuchera had moved over a few inches. I lifted a leaf and the whole plant came off, just like a toupee! That's when I learned about root weevils. Then I had two affected plants, this year five, in the same area. I never actually saw any larvae or weevils, though.

My questions:
Might this to spread to other plants near by (euonymus, viburnum, hebe, vines)? If I just take the heucheras from this area, can I reasonably expect the problem to stop?

Thanks,

Maro

I favor the use of nematodes, when we first bought them, we were told not to use them until the temperature was up in the 60/70's, and if we did it for 2 or 3 years the nematodes would multiply in the soil so we wouldn't have to do it for quite awhile. I also grow named varieties of Begonias and they also get watered with nematodes in June/July.
Now I don't know if this works, this winter while searching the internet for information on Fuchsias I found this hint, someone read in a Dutch book to stop Vine Weevils: put halves/slices of raw potato on the soil. The weevil lays its eggs in the potato instead of the soil. Change the potatoes every 10 days. Also another tip he mentioned was to water, not spray with a Pyrethrum based insecticide, repeat watering 2-3 times, wait 1 week and water 2-3 times again. I'm going to try the potato method myself, curious to see if it works.

A......

Thank you for your reply -- interesting about the potato!

I read the rest of the post earlier, and I will get nematodes for later this year. But I did wonder about spreading to other nearby plants, and my other question.

I know I can ask on the pests forum, too.

Was weeding yesterday. Touched Heuchera 'Lime Ricky' the entire plant moved, it was chewed off at soil level.....I have never had this happen before.

I've got plenty of notched Rhodies but never the entire Heuchera.

Safer's has a relatively safe product called "Trounce" which you can drench into your affected plant and the soil around it. That will take care of the root maggots, but I imagine once they are established you will want to drench very early in the season for a few years in a row to get the resident pest population down to a manageable level.

I have since lost about ten Heucheras to root weevils. :(

Some of my dwarf Rhodies are damaged so badly that they don't bloom much at all and they look awful. I hate to rip them out because there aren't that many small enough for my garden.