Mites on raspberries

lifespeed(9B San Jose)August 18, 2009

I have a 15' row of Heritage red raspberries that appear to have a mite infestation. They are small, teardrop-shaped and whitish. Some of the raspberry 'kernels' are completely white instead of the usual red-purple. Perhaps the mites are sucking them dry?

Anyway, this is looking like a problem that is getting progressively worse, not better. I am under the impression that miticides are a specific product, and that many insecticides are not useful against these pests.

Are there any products that can bring these pests under control? What about minor details like toxicity, pre-harvest interval, etc. I have seen lots of miticides for flowers, but I'm not sure they are acceptable for food crops.

I don't suppose there is any chance soap and/or oil will kill them? What about this non-toxic miticide?

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lifespeed(9B San Jose)

Just thought I should mention these mites are fairly fast-moving, if that helps with identification. I looked at http://www.sel.barc.usda.gov/acari/index.html and read that yellow mites are notably fast . . .

    Bookmark   August 18, 2009 at 12:37PM
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fruitnut Z7 4500ft SW TX

I'm sure SucraShield is safe enough. So far I've only tried it on aphids. At label rates it wasn't very effective. Maybe it would work well at higher rates.

There are very effective miticides that are approved for fruit. But they are very hard to find. I'm like you and not sure how safe the ones we can find would be on fruit.

The active ingredient in Avid, abamectin, is also avaliable in Agri-Mek. Agri-Mek is approved for fruit, I don't think Avid is. I was lucky to get ahold of some Agri-Mek. One spray controls spider mites in my greenhouse all yr long. I find that amazing since I have a 300+ day growing season.

Some other miticides approved for fruit are Acramite, Zeal, Envidor, Mesa, Nexter, Fujimite, Kanemite, and I'm sure there are more. But I couldn't find a source last I looked.

Wish I could be more help.

The Fruitnut

    Bookmark   August 18, 2009 at 12:49PM
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larry_gene

Your white drupelets may be the result of UV damage from the sun. It appears as random white drupelets. If the kernels are white but still plump, they have not been sucked dry; this would cause them to shrivel and turn brown, and UV damaged kernels also do this eventually. It results in a slightly crunchy berry when eaten.

    Bookmark   August 18, 2009 at 11:24PM
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lifespeed(9B San Jose)

I had a suspicion of sun damage. Thanks for confirming. Yeah, they are still plump, but some appear to have shriveled. Perhaps just more time.

Raspberries are strange. They seem to want sun, but not too much.

I'm still not too keen on the mites, tho.

    Bookmark   August 19, 2009 at 12:24AM
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glenn_russell(6b RI)

lifespeed-
Right. I was going to say the same thing as larry_gene. You can Google "White Druplet Disorder" for more information. It seems that some varieties are more susceptible than others.
-Glenn

    Bookmark   August 19, 2009 at 9:03AM
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larry_gene

Recent temperatures above 90 degrees have induced a second, although minor, outbreak of white drupelets on my blackberries.

The neighbor's everbearing raspberries have not had any white this summer, but the plants only get sun from 1:00 to 2:30.

Try shadecloth in the future if practical.

    Bookmark   August 19, 2009 at 11:19PM
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Beeone(4 N. Wyo.)

Are you sure you have mites? They are difficult to see with the naked eye, and really need a magnifying glass to ID. Typically they are found on the undersides of the leaves and infestations move from the bottom of the plant upwards. Infested leaves will tend to have webbing on the undersides which is easier to see than the mites. The leaves will also take on a slightly speckled appearance on top, kind of like they were lightly sand blasted, and the undersides get a greyish cast. When looking at them through a magnifying glass, they tend to look like very tiny spiders or ticks.

Although heavy infestations can develop on their own, an infestation often occurs after heavy use of insecticides which kill off their predators. Another reason to spray only when you have a problem that needs spraying. Drouthy conditions and dry areas also tend to be more susceptible to mite infestations.

There are predatory mites which you can purchase and release which will keep the pest mites under control if you avoid other insecticides that would kill them.

Many of the regular insecticides will also control mites, although they aren't necessarily labeled for that. Kind of like many insecticides will "control" humans and they aren't labeled for that either! Sevin will knock the mites out(it is frequently recommended for mite problems on conifers), usually one spray is all that is needed when signs of mites move above the bottom 1/3 to 1/2 of the plant. Bifenthrin will also control them, but don't know that it is labeled for raspberries. It is currently being sold under the label of SuperMax in a red bottle. It is a highly effective pyrethroid insecticide, but should be used sparingly and in rotation with other non-pyrethroid sprays to prevent resistant pests from developing and building up. I don't think the label mentions anything about preventing resistance, but it is such an incredibly valuable insecticide for some agricultural crops. It's effectiveness makes it prone to developing resistance in target pests, so I only use it with a second insecticide with a different mode of action to help prevent resistance. It still reduces total insecticide use dramatically because of its effectiveness. I don't know what the clearance time is with these before picking the fruit, probably 3-5 days with Sevin and a week to 10 days at least for bifenthrin. So you may not want to spray this year and look more at going after them before the fruit ripens next year. Insecticidal soap might be something you could use while the fruit is on, though.

    Bookmark   August 20, 2009 at 2:14AM
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