How destructive are Colorado Potato Beetles?

[marches]

We rarely see them in the UK (although they've infested Europe and could easily naturalize here if given the chance).
What parts of the plant do they attack and how destructive are they?
How can you control them without chemicals?

[Tom Wagner]

CPB otherwise known as Colorado Potato Beetle is very destructive. Back in Kansas where I spent the majority of my life it made potato production problematic. We used to use sparingly chemicals like Sevin dust and/or arsenic of lead, but it made gardening organic tough to use that stuff. So we mostly didn't and let nature take care of the potatoes outside of just picking off the darn things. They eat the majority of the leaves and the yield can be horrible if they are heavily infested. I controlled them somewhat with selecting for germplasm that was high in foliar alkaloids.

[tickledtoad]

I can only suggest what has worked well for me. As an example of how destructive they can be, some spuds planted in a neighbors garden about 4 years ago, were completely denuded...essentially no leaves and a fair portion of the stems as well were simply gone. Without some kind of controls, or handpicking, this kind of damage is very common in our area. Less than 150 feet away, my potatoes were not touched. I have very honestly and literally only picked a single adult "potato bug" from my plantings in the last 15 years. Yes...15 Years, and I do plant a fair number of spuds...they take up about a third of my food gardens...BUT, they don't get that space alone, and that seems to be where a part of my success with them lies.

As soon as any greenery breaks ground, I start mulching with a light layer of straw...about 2 inches (but prior to that, I make sure I have planted a bunch of beans as a collaborative crop). Something like this is typical:

A row of bush beans on the outer edge of a raised bed, a row of spuds, a row of pole or semi-runner beans in the middle, another row of spuds, and a last row of bush beans. The beans only need to stay off the ground...who said they must have poles or trellises to climb on? Both the beans and spuds do just fine with the beans rambling through them. Although I do often use a few poles and some twine to help with the very heavy (and taller) more aggressive pole types.

I'm experimenting with multiple other plants to grow with or near spuds to try see which are most effective in mixing up the chemical signals which are telling the Col. Potato Beetle where the goodies are at.

Back to the straw. It has been my observation that the spud bugs LOVE to see bare soil when those first egg layers make their appearance 2-3 weeks before the babies start munching. If there isn't any bare soil around the young spuds, they get downright inhospitable and take their appetites elsewhere The straw seems to help point them to those that garden without mulch, with the not too shabby side effect of keeping the spuds a bit cooler and more moist (slugs do a bit of damage to lower leaves, but has not been too much for a decent toad population). When the spuds are a few inches tall, I'll throw 2/3 shovels of compost around each plant then add as much straw as the spuds can handle without burying them completely.

I took a few pics earlier today and will try get them loaded within a day or so. so you all can see how this methods has worked for me. As an example the best Muruta TPS plant is 40 inches tall, and 35 inches across, with the 5 next best right on its heels (and other than a couple of runts, most of the other 16 are no slouches)...a bed of 11 Squat Orange TPS progeny average 18-24 inches tall by 12-26 inches across, etc.

Oh, by the way, bare soil in neighboring raised beds (18 inches away) in no way has made any difference in convincing the spud bugs to try my restaurant out.

Nasturtiums seem to be promising...not sure yet about radish, cukes and melons, and since I already use a lot of radish as an attractant for beneficials, and it doesn't have a decent canopy to shade the area under it, I likely won't try crowd my potatoes with them to try chase potato bugs...the beans have worked great for me, and it happens to be about the right amount we use in a year. I do plan on trialing a bit more with the cucurbits though.


Enjoy!
tickledtoad

[marches]

Aug 22, 2014 18:46:57 GMT -8 tickledtoad said:

I can only suggest what has worked well for me. As an example of how destructive they can be, some spuds planted in a neighbors garden about 4 years ago, were completely denuded...essentially no leaves and a fair portion of the stems as well were simply gone. Without some kind of controls, or handpicking, this kind of damage is very common in our area. Less than 150 feet away, my potatoes were not touched. I have very honestly and literally only picked a single adult "potato bug" from my plantings in the last 15 years. Yes...15 Years, and I do plant a fair number of spuds...they take up about a third of my food gardens...BUT, they don't get that space alone, and that seems to be where a part of my success with them lies.

As soon as any greenery breaks ground, I start mulching with a light layer of straw...about 2 inches (but prior to that, I make sure I have planted a bunch of beans as a collaborative crop). Something like this is typical:

A row of bush beans on the outer edge of a raised bed, a row of spuds, a row of pole or semi-runner beans in the middle, another row of spuds, and a last row of bush beans. The beans only need to stay off the ground...who said they must have poles or trellises to climb on? Both the beans and spuds do just fine with the beans rambling through them. Although I do often use a few poles and some twine to help with the very heavy (and taller) more aggressive pole types.

I'm experimenting with multiple other plants to grow with or near spuds to try see which are most effective in mixing up the chemical signals which are telling the Col. Potato Beetle where the goodies are at.

Back to the straw. It has been my observation that the spud bugs LOVE to see bare soil when those first egg layers make their appearance 2-3 weeks before the babies start munching. If there isn't any bare soil around the young spuds, they get downright inhospitable and take their appetites elsewhere The straw seems to help point them to those that garden without mulch, with the not too shabby side effect of keeping the spuds a bit cooler and more moist (slugs do a bit of damage to lower leaves, but has not been too much for a decent toad population). When the spuds are a few inches tall, I'll throw 2/3 shovels of compost around each plant then add as much straw as the spuds can handle without burying them completely.

I took a few pics earlier today and will try get them loaded within a day or so. so you all can see how this methods has worked for me. As an example the best Muruta TPS plant is 40 inches tall, and 35 inches across, with the 5 next best right on its heels (and other than a couple of runts, most of the other 16 are no slouches)...a bed of 11 Squat Orange TPS progeny average 18-24 inches tall by 12-26 inches across, etc.

Oh, by the way, bare soil in neighboring raised beds (18 inches away) in no way has made any difference in convincing the spud bugs to try my restaurant out.

Nasturtiums seem to be promising...not sure yet about radish, cukes and melons, and since I already use a lot of radish as an attractant for beneficials, and it doesn't have a decent canopy to shade the area under it, I likely won't try crowd my potatoes with them to try chase potato bugs...the beans have worked great for me, and it happens to be about the right amount we use in a year. I do plan on trialing a bit more with the cucurbits though.


Enjoy!
tickledtoad

Wow, interesting stuff. Maybe some sort of low ground cover other than grass could be sowed.

[paquebot]

Spinosad is highly effective and also organic. I was skeptical since CPBs readily develop immunity to many of the usual chemicals. On the market in the US, it's in "Colorado Potato Beetle Beater". Our local 1½-acre community garden complex used to be rampant with CPBs and were totally eradicated in two seasons. None showed up at all this year.

Martin