Is the damage you are seeing on your rhododendrons what you would describe as severe, or minor and cosmetic as a light infestation would be.

I did find the article you quote (Nov 2005) Checking the online label for the above product and I find (Ortho Home Defense MAX Termite & Destructive Bug Killer Concentrate - 2.4% bifenthrin) "do not spray on edible or ornamental plants. Accidental drift onto plants should be rinsed off immediately."
Talstar, as I understand it and hope Rhodyman or someone will correct me if I'm wrong, is used in the growing media - a container drench, or as granules applied topically to container 'soils', not as a spray to the plants themselves.

A more conservative approach (s) to weevils (if severe enough they need attention) is to cut back any branches touching ground, then apply a barrier like Tanglefoot low on main stems to block access of adults. Going out in the evening (flashlight) and hand picking - and I fully admit to being repelled by the crunch they make when mashing them. Beneficial nematodes applied to the soil in earliest Fall when the soil is still warm but rains have begun again.

I think I've seen one, possibly two, photos here over the years of a weevil infestation on a rhododendron severe enough the plant was in decline, that I felt like I could recommend a chemical approach....

Moderate damage, I have probably 75 rhodies on my property, some have no weevil damage, some are pretty extreme. This isn't new damage, they have been eaten up like this for years. I just want to start fighting back against the weevils to give the rhodies a chance.

As many rhodies as I have and as big as some of them are a chemical treatment is preferred, not realistic to go out at night and pick them off.

Speaking of that, as I stated I'm not familiar with weevils. What times of year are they active? When is the appropriate time to apply Ortho Home Defense MAX? I found it at Home Depot in granular form. Since it's marketed mainly to put around your house's foundation I'm not sure what people recommend re: what times of year to apply and how frequently and even how much per plant.

I may do the Tanglefoot thing too when I get a chance but want to get some attack started if they're already chewing this time of year. Can the Tanglefoot be applied directly to the bark? Or I need to find some way to wrap the bark then apply (more work/more time consuming)?

Thanks!

I can see where both hand picking and Tanglefoot could be time consuming with that many plants. You might find it interesting that some rhododendrons appear to taste better to weevils and are more susceptible than others - suspect it may have to do with the thickness of the leaf on a particular variety, and how much indumentum present on the leaf underside.

Harold Greer, Greer Gardens Oregon- "For the home gardener the most often used control is Orthene which should be sprayed on the foliage at about three week intervals from about May to October, depending on the weather. This is done to control the adults but is not fully effective because the weevil may lay eggs under the plant before they eat the foliage that has been sprayed. Better control was possible with long lived chemicals which could be placed in the soil under the plant, preventing the eggs from hatching, hut these chemicals are no longer available for environmental reasons. There is a biological control in the form of a nematode which can be applied in the fall to control the larvae. While this approach 1s promising, it has limitations in that the beneficial nematodes are very sensitive to temperature and moisture extremes and will not live over winter. If applied to soil that is too cold, too wet, too dry or too hot, they will die and provide no control. Best control is achieved by using both chemical and nematode methods with proper timing."

If it helps you to plan an attack, although I really don't know the best time to apply the bifenthrin and someone else here will have thoughts on that, when or even if you could time it -
"The adults emerge in May to June and feed on foliage from twenty-one to forty-five days before they lay their eggs"

Here is a link that might be useful: Helm-Bainbridge-rhody weevils life cycle PNW

In answer to your other question, you can apply Tanglefoot directly to bark, but its going to stain and you will see it for a number of years, longer than it will actively be working for you.

Thanks for the info morz8! I think what I'll do is apply the bifenthrin May 1 and June 1 and also on May 1 make sure eaten rhodies have no branches touching ground and apply Tanglefoot. Let's see how the weevils deal with all of that!

wynsworld, when applying a product in an off-label manner, you should call the toll free number on the label and ask for specific directions. Some off-label uses of pesticides are legal, as long as the use follows the intent of the label. You will find that a quick call will result in some good information.

Since that article suggesting the use of it for weevils and rhodies was from 2005 I thought some members here would have already tried it and could report application, how well it worked, etc. I highly doubt calling Ortho would yield as much information as someone who has rhodies and has used the product themselves. And if it doesn't work well do you seriously think Ortho would say that? They're not objective, they're selling a product...

You are dead wrong in your supposition, wynsworld. The people you will talk to when calling the information hotline are in the business of helping people like you use their products properly, safely, effectively, and legally. They are one hundred percent willing to tell a caller that they MUST NOT use their product in a certain way because it may: damage the plant, not do the job the user intends, harm the user, harm non-target animals, harm the environment, or be illegal. Ortho has nothing to gain from people who get themselves into trouble by misusing their products and a great deal to lose.

That number is the very first place you should go to for good information. Look on the label and call the number listed. If you have never done so, you might be surprised. I've called them many times over the years, mostly to see to what they had to say about certain off label uses. I've never had a sales job pulled on me, but have been given a great deal of good information....mostly in the form of "NO, you cannot use our Ortho product for that use." But plenty of times to explain how to safely use it for something that might not be listed on the label.

Chemical companies spend multimillions of dollars in research in order to produce their products and the labels that are considered federally legal documents. They want their customer to be successful and will help you to that end. On the other hand, if someone wants to do something dangerous or even non-effective with their product, they'll tell you immediately that you cannot.

I suspect that they will be happy to bless your use of this pesticide for your purpose, and why not take advantage of their insight? They have an awfully lot at stake that you will be satisfied with their pesticide and live to tell the story. ;-)

I'll try it but if 50 people are interested in using this product for Rhodies isn't the point of this forum to SHARE information???! This suggested use was a posting from 2005 and I'm posting this in a Rhody forum, I'm quite surprised I'm the first person in this Rhody forum since that posting in 2005 to show interest in this product.

I would feel much more comfortable hearing experiences from Rhody lovers who have used this product on their Rhodies to share what they've learned vs. call a company that makes chemicals who may or may not have any knowledge of its use on Rhodies.

As far as it being illegal, makes no sense, product is sold locally and is used to treat pests listed outdoors so the legality makes no sense at all.

can anyone tell me what the dilution rate is for Ortho Home Defense for a soil drench?

ricard0: I'd be very cautious about using Ortho Home Defense as a soil drench at all. The original article advocating its use for vine weevils is 9 years old. In that time, there have been many changes in formulas and ownership (Ortho products are now owned by Scotts, for example, even though the original Ortho name is still used). If vine weevil is such a serious problem as to require treatment with a pesticide - most rhododendron growers just live with weevil damage - you'd be better off contacting your County Extension Service or State Agriculture Department for their advice and recommendations.

I agree. Weevil damage is 99% cosmetic and is only harmful to young plants in a very small number of cases. I always encourage my clients to just live with it.......the weevils are omnipresent in my area and treatment would need to go on ad infinitum. I am much more willing to live with a few holes in plant leaves than I am to toxify the planet unnecessarily.

If the damage is so severe as to be unsightly, simply relocate that plant to a less visible location. There are many rhodies that are not bothered by root weevils at all - substitute one of those.

I have never used a chemical on my rhodies. Very few seem to be susceptible to the weevils to the point the plant looks bad. Those that are, I make sure the branches aren't touching the ground. That solves most of the problem right there. I can see where Tanglefoot can take care of the rest.
I did have a purple flowered rhododendron I got off a landscape job once that was showing a lot of weevil damage. The owner said, "Get rid of it". I took it home and put the root ball in one of my ponds for a couple of days and then planted it after removing branches that were touching the ground. Result; no weevil damage the following year on the new growth. Apparently the larvae can't hold their breath for two days,... and drowned.
Mike