Bad news in Prince Edward Island

Controlling pests of bamboo

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ShmuBamboo
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Re: Bad news in Prince Edward Island

Post by ShmuBamboo »

Malathion, Sevin and some pyrethrins are usually not the best products for spider mite control, and they may even make the problem worse. Malathion and Sevin (carbaryl) are both broad spectrum and they kill off mite natural enemies and can lead to greater spider mite outbreaks if the mites are not all killed, or if they return from some other place. UC Davis studies also show that mites exposed to Sevin can reproduce faster than untreated populations. Carbaryl, some organophosphates, and some pyrethroids appear to favor spider mites by increasing the levels of nitrogen in leaves. Malathion can actually aggravate spider mite problems, even though it is advertised as effective for mite control. Sprays like Sevin and malathion are also contact sprays and they are not systemic. This means that you have to contact all the mites when spraying to be effective. Spraying the undersides of bamboo leaves can be difficult, as that side of the leaves are more water repellant and that is where mites usually reside. The sprays also have to penetrate the fine mite webbing to contact the critters.

When spraying for bamboo mites, it is better to use a selective systemic miticide such as Avid or Floramite designed to kill the various stages of mites and eggs, or an insecticidal soap or an insecticidal/agricultural oil which will kill all all stages of mites and their eggs on contact. Avid or Floramite are both systemic insecticides, meaning that they pass into and through the leaves and remain there for a period of time for better control of mites, as you do not have to contact all the mites with spray to be effective. Petroleum-based horticultural oils and plant-based oils such as neem, canola, or cottonseed oils are also good. There are also a number of plant extracts that are effective on spider mites. These include garlic extract, clove oil, mint oils, rosemary oil and others. Oils and soap sprays must contact all adult and imature mites and their eggs to be effective. For this reason complete coverage, especially on the undersides of leaves, is essential when spraying with oils and soaps. Multiple applications are usually more effective. It is best to spray oils when temperatures are below 60 degrees F. to reduce leaf stress and damage.
Happy trails...
tncry
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Location: Prince Edward Island Canada - Zone 5

Re: Bad news in Prince Edward Island

Post by tncry »

Great info shmu. I'll use an oil, soap mixture next year when I spray. I used the malathion because I wasn't really spraying any bamboo but just the ground below plants I cut down and mainly because of accessibility. In other words, I found some malathion in the barn.

If the mites survive the winter and seem to have spread to other plants, I'll be looking to buy some Avid off the net.

TC in PEI
stevelau1911
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Re: Bad news in Prince Edward Island

Post by stevelau1911 »

Well, I cut all the culms on two spectabilis, one japonica and one nuda plant. I also cut out all the old growth on two aureocaulis plants. Then I sprayed the ground and surrounding plants with a miticide. Hopefully that helps contain the mites for this year and I'll have to be vigilant next Spring.
I don't think cutting down all the culms would have been necessary since you don't have that much plant material to spray. One idea in preventing mites from having any access to the underside of the leaves is by using wilt-pruf which makes it so they can't live underneath the leaves.

Also, only a little bit of miticide does a long ways so if you get a couple ounces of it, it should be enough to eradicate your infestiation with multiple applications. It only takes a few drops to make an effective spray with a gallon of water.
ShmuBamboo
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Re: Bad news in Prince Edward Island

Post by ShmuBamboo »

tncry wrote:If the mites survive the winter and seem to have spread to other plants, I'll be looking to buy some Avid off the net.

TC in PEI
I would nuke them with oil spray now while things are 'warmer', and then let zone 5 cold kick in. Fewer numbers this time of year will mean even fewer or none on the other side of winter. Its a balmy 36 F. outside here now. I may get early snow this year. It was 85 F. here just 2 weeks ago.
Happy trails...
johnw
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Re: Bad news in Prince Edward Island

Post by johnw »

Have been in Newfoundland so apologies for the delayed response. I agree an oil spray would make a great deal of sense.

I don't think Malathion will have any effect on mites whatsoever. As for carbaryl (sevin) as Schmu says avoid it like the plague. When I worked for a west coast nursery that specialized in conifers, when a new dwarf spruce find was trialed they would spray it and all surrounding spruces with sevin, that way if the new spruce cultivar was susceptible to mites they were bound to get them in a big way. Albertas were notorious mite magnets and the brooms on Alberta like Gnom and Pixie et al even worse. The mites would go crazy with sevin, killed all the predators. They did not want to introduce any spruce that had a susceptibility to mites.

May get a light frost tonight.

johnw
johnw coastal Nova Scotia
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