Technically you're supposed to look to the label for such guidance. Other than that, since fall is the recommended time for blackberries that is probably when it would be most efficient to spray honeysuckle also.

i dont understand.. because i dont know what JHsuckle is ...

is it an invasive weed.. ???

is it evergreen??? you have to spray green leaves ...

yes .. roundup works in winter.. though.. depending on how cold it is ... the plant may not 'appear' to start yellowing and dying.. until it is warm enough for the plant to show the effects ...

on the other hand... if its a problematic vine.. i would suggest the expensive applicator at the link.. with 100% [aka 41%] roundup ... cut the vine at ground level ... and apply/drip on the cambian layer ... and keep at it for a year or two.. until the vine understands who is in charge ...

return undiluted roundup to its original container for storage ... and clean out the applicator ...

in my hosta beds.. in theory .. with them all dead to the ground.. i can go out there right now.. and obliterate the perennial weeds ... but they will remain green until about 4/15 .. and as the soil warms ... and the plant gets active enough to 'use' what i sprayed.. and die ...

do insure you buy the product with sticker/spreader in it ...

ken

Here is a link that might be useful: the applicator form, not the brand name ...think dollar store

from the label: "Use any time weeds are actively growing. For best results, apply on a warm sunny day when daytime temperature is above 60 degrees and no rainfall is forecast for 24 hours."

That wouldn't be referring to woody plants like blackberries, which are sprayed in fall so the overwintering buds in the crown are (hopefully) killed.

Even with vining non-woody perennial weeds like giant morning glory a recommendation that is made is to wait until flowering has commenced, indicating the top is large enough for enough chemical to be taken up to damage the roots.

i googled: eradicating Japanese Honeysuckle

got about a bazillion links.. and chose the one below .. and it clearly IDS how to use roundup in this fight ... where it says:

Glyphosate herbicide (tradename Roundup) is the recommended treatment for this honeysuckle. A 1.5-2% solution (2-2.6 oz of Roundup/gallon water) applied as a spray to the foliage will effectively eradicate Japanese honeysuckle. The herbicide should be applied after surrounding vegetation has become dormant in autumn and before a hard freeze (250F). Roundup should be applied carefully by hand sprayer, and spray coverage should be uniform and complete. Do not spray so heavily that herbicide drips off the target species. Retreatment may be necessary for plants that are missed because of dense growth. Although glyphosate is effective when used during the growing season, use at this time is not recommended in natural areas because of the potential harm to nontarget plants. Glyphosate is non-selective, so care should be taken to avoid contacting nontarget species. Nontarget plants will be important in recolonizing the site after Japanese honeysuckle is controlled.

Here is a link that might be useful: link

effectiveness of glyphosate declines under 70 degrees F. 2,4-D is highly effective against woody plants without the temperature reducing efficacy

immediate effect is reduced..

until the plant warms and becomes more active.. and then it becomes effective...

and the 'sticker' means it will stick to the plant.. until the plant becomes active ..

i dont think we are disagreeing at all ...

and just to be sure.. you can NOT allow spray on ANYTHING ELSE GREEN.. or it will die also ... and that why i prefer the hand cutting and dripping ...

ken

"immediate effect is reduced..

until the plant warms and becomes more active...and then it becomes effective..."

Glyphosate/RoundUp will quickly break down and bond so that it will no longer be effective. You can't apply the chemical for later effectiveness.

Mine still had green leaves last time I checked but it sounds like fall would've been a better time to spray. It's easier to see when it's the only thing that's green twining up through my other shrubs.
Since I missed spraying it in the fall, I still may try later this month if I can catch a day when it's warm and sunny. I'll let you know if it works.

Hi, christie:

You certainly can apply glyphosate to effectively kill Japanese Honeysuckle in late winter/spring. Simply follow the label recommendations for appropriate concentrations and climatic conditions.

Restoration ecologists and land managers do this all the time - and have been doing this in Louisville this month.

Good luck in eradicating this pest.

VV,

There was another discussion a few months ago about the effectiveness of glyphosate during winter months. I think it was Ken that was asking about it. The general consensus was that it was much less effective during colder periods (as Sam and Strobiculate alluded to above) when the plant was dormant. Of course, less effective is a relative term, so that doesn't mean it wouldn't work. What's your experience been regarding the relative effectiveness during dormant periods? Do you apply it any differently (rate, etc)?

I suppose the debate surrounds "relative effectiveness during dormant periods", and what is/isn't dormant.

I don't know that I would have any recommendations for glyphosate treatments on dormant deciduous plants during winter months - haven't tried that.

christie is looking to eliminate Japanese Honeysuckle (Lonicera japonica), which is an evergreen vine at her location, as it is here in the Ohio River valley. The rate at which it is translocated through the plant will be different, depending on the biological activity of that plant. The warmer the weather is (and the warmer the soil is), the more activity and thus the rate of translocation.

The treatments performed in Louisville's parks vary, depending on what part of the plant is being treated. The recommendations pertain to using 44% glyphosate concentrate as the source of active ingredient.

Foliar application calls for 2% concentrate and 98% water, with surfactant. Application to cut stems calls for 25% concentrate and 75% water.

Temps above 40F (meaning overnight, not just daytime) is the benchmark for winter work.

I believe the previous comments are not passing judgment on effectiveness by the rapidity at which death is observed.

I can't believe I'm posting a picture of honeysuckle!
As the OP pointed out, it roots at the nodes. I took this picture today. Forget about waiting for warmer weather and do what I did. Trace back to the main stem. Uproot this and the secondary stems will come up with it. Lonicera japonica is found from California across southern and midwest states to New England and the Great Lakes region. It's spread is relentless and aided by the road crew mowing equipment. {{gwi:242622}}