pre-emergents and post-emergents

ralph_d(6b)September 28, 2012

Any known issue with using pre-emergent herbicide around a newly planted potted tree (thujas, hollies, junipers, spruce)? Any active ingredient preferences or issues?

Also, any advice for which broadleaf herbicide poses least risk to conifers? I am planting the privacy screen so the mature tree drip line will be ~1ft inside a perimeter fence, but I know a good part of the root system could be vulnerable to herbicide treatments along fence (e.g., 2,4-D). I want to stay on top of weed control along the fence so the fence lasts longer and so neighbors would have fewer reasons to apply their own random herbicide along the fence lines. Thanks for any guidance.

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jalapenos

Herbicides containing Triclopyr do not affect conifers nor grasses. It is a selective herbicide that is used for the control of woody plants. I have found it especially useful in controlling creeping charlie when applied at the right moments.

As with any herbicide, please read and understand the label fully before applying as Triclopyr is immensely hazardous to aquatic creatures and the animals that prey on them. However, Im with you in keeping the neighbors from doing more harm by indiscriminately spraying...

    Bookmark   September 28, 2012 at 12:27PM
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ken_adrian Adrian MI cold Z5

i would avoid pre-emergents in a pot .. especially newly planted ... just because ...

do you have so many pots.. that you cant pick a few weeds once a month???

i use generic roundup above the soil .. there are tricks to using it.. bottom line.. ULTRA low pressure with big drops which gravity pulls to the early ... roundup becomes inert when it hits the soil.. only works on green tissue [the weeds] .. irrelevant to the roots ...

you said: the mature tree drip line will be ~1ft inside a perimeter fence

size estimates are at 10 years ... so at 20 .... they have the potential to be twice as wide ... so i wonder about your statement.. should you wish opinion on such.. provide some facts ... like what cultivar you are using ... and the size of the yard ... etc ...

ken

ps: a conifer is sexually mature when it is old enough to cone .. really has nothing to do with size potential ... i think you are confusing 'mature' with 'size' .. as trees.. conifers never really stops growing ... though they slow down with extreme age .. long after you will be dead ...

    Bookmark   September 28, 2012 at 12:31PM
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davidrt28 (zone 7)

Be careful. Some forms of triclopyr can affect some conifers, such as pines. In a home garden there really should be no need to overspray an entire area as in forestry. Just use a hand sprayer, and if a little bit his a conifer, you have nothing to worry about it. (If it hits a non-conifer, you better have some water handy to wash it off)

I've used preemergent around all sorts of plants (assume you mean surflan?) and it doesn't affect them. Likewise, there's no reason to directly overspray them though. A handful of plants are listed as sensitive though it probably wouldn't kill them, just deform their growth for a year. I believe douglas fir and deutzia are on the list.

Here is a link that might be useful: http://pnwhandbooks.org/weed/other-areas/forestry-and-hybrid-poplars/recommendations-area-spraying-using-boomless-ground-equipmen

    Bookmark   September 28, 2012 at 1:41PM
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davidrt28 (zone 7)

"? I am planting the privacy screen so the mature tree drip line will be ~1ft inside a perimeter fence, but I know a good part of the root system could be vulnerable to herbicide treatments along fence (e.g., 2,4-D). I want to stay on top of weed control along the fence so the fence lasts longer and so neighbors would have fewer reasons to apply their own random herbicide along the fence lines. "

This must be a rather small property. In that case, just use a couple rolls of weed barrier fabric. I think reports of their harm to soil or plant health are exaggerated in most cases; certainly, conifers are tough enough that they will be fine.

If it's a larger property >=0.75 acre, why in the world are you putting the plants so close to the fence? Remember, what grows past the fence your neighbors will have the right to trim, so you could end up with some very lopsided plants. 3' makes more sense with something that has a fastigiate habit, and 6'-10' more sense for things that do not.

    Bookmark   September 28, 2012 at 1:46PM
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ralph_d(6b)

Thanks for the suggestions. We have a few acres, but the land was divided such that the house is close to one of the property boundaries that needs some visual/sound screening. I planned on using shorter and narrower conifers for this part of the yard, but I will also increase width of the buffer between the estimated 'final' tree spread and the fence for future generations. A wider buffer will also better protect against improper herbicide treatments near the fence line.

I do have a lot of fence line to maintain (some currently lined with eastern cedar). I thought I was OK using 2,4-D (amine) since it doesn't transfer via evaporation, but I've read internet postings that this broadleaf herbicide can wash off foliage and be absorbed by tree roots. I'll check into the triclopyr - it sounds like a better choice for spot treatment along the fence line since I want to avoid killing grass growing on the other side of the fence.

I am planning for a large early spring planting using some variation of the staggered row approach. The next big task is to refine the cultivar list of what's available (local and internet) after meeting all my initial criteria. If the research doesn't go well, I'm sure I'll be back to the forum to decrease the chance of major disappointment.

Thanks,
Ralph

    Bookmark   September 28, 2012 at 3:20PM
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jth97381

So this is what I do. I try to treat twice a year.say November and March. I use Goal(oxyflurofen) and Surflan(Oryzalin). Works in containers and in the field. You can spray directly over the foliage, while dormant, and you wont even get any burn. The ground does need to be fairly clean, however small weeds will be killed on contact. It needs to be sprayed with about 1/4"-1/2" or rain expected within 48-72 hours or irrigated in. Things stay incredibly clean. It works by killing the weed seeds as they germinate. Now dont take my word for it and like always you should do a small scale test before you go hog wild.

    Bookmark   September 29, 2012 at 1:24AM
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ralph_d(6b)

In practice, what's the difference between using Surflan versus Goal as a pre-emergent? I'll try to read up, but it would be good to get a practical summary before I try to sift through the more technical details. I am trying to learn the differences so I have more options. Keeping the seeds from germinating in the first place would result in considerable less post-emergent treatment. I imagine none of the pre-emergents help with weeds that sprout from roots.

    Bookmark   September 29, 2012 at 3:34PM
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dcsteg(5 Shawnee, KS.)

The myth about landscape cloth.

Dave

Here is a link that might be useful: Landscape cloth.

    Bookmark   September 30, 2012 at 8:46AM
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davidrt28 (zone 7)

Dave, I think they they may be overused and are useful in a limited set of circumstances. A row of conifer screening happens to be one of those uses. Yes, the fabric (and I was only recommending a geotexile type, not a roll of impervious black plastic) will degrade. By the time it degrades completely, the conifers will have grown large enough that their shade will start to cut down on weed germination. In my observation, they undoubtedly increase soil moisture retention and reduce the need for watering. And in their first couple years, they do keep weeds down, which is the most crucial period for reducing weed competition as the plants are getting established. Later on, the few weeds that start growing in the mulch are easy to rake or pull out.

I've had some in my landscape now for 5 years, all the plants around it have grown just fine, I've never had to water them in the past 3 droughty summers, and I expect in 5 years it will probably mostly degrade but by then it will be filled in with mature plants and there will be less light for weeds to grow.

One size does not fit all and the article you posted has some good points, but I stand by my recommendation.

BTW Ken's recommendation to not make a screen of a single plant type is good too.

    Bookmark   September 30, 2012 at 6:10PM
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dcsteg(5 Shawnee, KS.)

davidr28

Just presenting some unbiased facts and not in anyway suggesting you or anyone else are wrong for using landscape fabric.

If you are comfortable using it that's fine with me.

Dave

    Bookmark   September 30, 2012 at 8:40PM
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jth97381

I use goal and surflan together. A good combo that controls 95% of weeds. If you have a lot of really established weeds, it will take some work to get those taken care of first. Probably with roundup and some other stuff depending on what your weeds are.

    Bookmark   October 1, 2012 at 2:01AM
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jth97381

I use goal and surflan together. A good combo that controls 95% of weeds. If you have a lot of really established weeds, it will take some work to get those taken care of first. Probably with roundup and some other stuff depending on what your weeds are.

    Bookmark   October 1, 2012 at 2:09AM
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jth97381

I use goal and surflan together. A good combo that controls 95% of weeds. If you have a lot of really established weeds, it will take some work to get those taken care of first. Probably with roundup and some other stuff depending on what your weeds are.

    Bookmark   October 2, 2012 at 1:54AM
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jth97381

I have no idea how that posted 3 times. Dang smart phones.

    Bookmark   October 2, 2012 at 8:42AM
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davidrt28 (zone 7)

I'm just glad it stopped!

    Bookmark   October 3, 2012 at 9:41AM
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