Professional Preen

Discussion in 'Pesticide & Herbicide Application' started by DMAN, May 2, 2002.

  1. DMAN

    DMAN LawnSite Member
    Posts: 76

    I recently purchased a bag of pro preen and i was wondering if it as good as the dealer says it is. I am in PA and thistle has become a major problem for me and i wanted to know if it is too late to apply it to the beds as past posts indicated that it has to go down early(March) or it will not work. Do you apply it before the new mulch goes down or on top of the new stuff?? any help or sugestions are greatly appreciated.
     
  2. tremor

    tremor LawnSite Bronze Member
    Posts: 1,476

    Dman,

    This will do a good job for you on most anual weeds if timed & applied properly (see label). You will get better results if it's applied prior to mulching. PreenPro contains Trifluralin which has a tendancy to bind with organic mulches. This has the effect of keeping the active higher up in the profile than the weed seeds you are targeting. In some extreme cases, it may be best to first pull out any excessive mulch from beds where pre-emergents have been known to fail. This isn't a very common condition though.

    Steve
     
  3. GroundKprs

    GroundKprs LawnSite Bronze Member
    Posts: 1,969

    Professional Preen is the same as Snapshot. Dow licenses Lebanon to use their own label on it. The Prof Preen is formulated at only 2.0% AI, compared to 2.5% AI for Snapshot, so watch your pricing. But this is a preemergent, only controls germinating weeds. Is your problem Canadian thistle?

    Snapshot or Prof Preen can effectively be used on top of old (last year's) mulch, to control the weed seeds that have landed in the mulch. To use mulch and a preemergent is a waste of chemical. If you properly mulch in the springtime, you are effectively smothering all the new weed seeds from last season. Just 1" of fresh mulch, spread evenly of course, will control all except tree seeds, which pre-ems won't control anyhow. Most all common weeds need light to survive immediately after germination, they do not have the energy stored in the seed to grow through an inch of mulch to get to light. Qualification: to me mulch is a finely ground, mostly bark product; if you are using all wood, or ground pallet type mulch, you will need the pre-em because reflected light will go through even 3"-4" of that junk.
     
  4. DMAN

    DMAN LawnSite Member
    Posts: 76

    Jim,

    Thanks for your response. The problem is canadian thistle in the beds.Also the mulch that is in the beds now is that colorized mulch(Junk!!!) with thistle growing rampant. I was wondering if i should spray the existing thistle with round-up and then apply pro-preen to prevent new germinations. I am considering using bark mulch as the new mulch however the lady likes the fact that this colorized mulch stays darker longer. I heard that this "new mulch" robs the soil of nitrogen, is that true?? Thanks again for your help.

    Dman
     
  5. GroundKprs

    GroundKprs LawnSite Bronze Member
    Posts: 1,969

    You will not control established Canadian thistle with any pre-emergent. It grows from an underground stem, 6" to 9" below the surface. This eliminates pulling it out also.

    Unless you want to dig out and throw away everytning down to a foot deep, Roundup is the only alternative. For open beds, repeat spraying of Roundup will eventually control Canadian thistle. Need repeated sprays because the underground stem will rejuvenate unless enough Roundup translocates from the leaves.

    In beds of ground cover, or if the thistle is mixed with desireable plants, hand wicking is the only way to get rid of it. Mix a container of Roundup, about 40% Roundup (commercial grade, 46% AI) and 60% water. Then put on a chemical resistant rubber glove, with a cloth glove over that. The cloth glove is your wick, dip fingers into Roundup mix, and wipe the leaves of the thistle. Make sure you get tops and bottoms of leaves wet. I like to have at least a foot of thistle stem above groundcover for first application, so you get a large amount of chemical into the plant on first shot. Then treat in future as new shoots pop up from still living areas of underground stem. Let them get tall enough to get a good dose when you wick. If you can get 3 apps during the year, you will have good control of it, and watch for stragglers after that.

    Hand wicking also works great for many weeds in ground covers: grass, poison ivy, wild onion, anything that sticks up above the ground cover. Try to treat when weed species is actively growing to get best control. This method is tedious, but a lot cheaper than digging out the offenders and replanting the bed, or pulling the weeds forever.

    Note: the above 40/60 Roundup ratio is my number for Roundup Pro. The original Roundup was mixed 50/50 and gave great results. When I mixed Roundup Pro 50/50, I got some burn on groundcovers around the target weed. Test the ratio for your own use and location; you may have to change it.

    Brief biological description at http://www.css.orst.edu/weeds/Canadian_thistle/biology.html
     
  6. tremor

    tremor LawnSite Bronze Member
    Posts: 1,476

    DMan

    You can control Canadian Thistle after it's up with Lontrel. Lontrel may be the only post emergent herbicide labled for over the top of "SOME" ornamentals that controls broadleaf weeds such as Thistle, Dandelions, etc.

    http://www.bluebooktor.com/Library/..\docs\label\L47578.PDF

    This is pretty cool stuff.

    Steve
     
  7. tremor

    tremor LawnSite Bronze Member
    Posts: 1,476

    Let me clarify that before someone beats me up. Lontrel is labled for "over the top" in the nursery/grower scenaio & even then only in specifically labeled plantings.

    When treating for Thistle (or any other labeled weed), use a "directed spray" to avoid contacting the ornamentals.

    Steve
     
  8. Tordonista

    Tordonista LawnSite Member
    Posts: 36

    DMan

    You can control Canadian Thistle after it's up with Lontrel. Lontrel may be the only post emergent herbicide labled for over the top of "SOME" ornamentals that controls broadleaf weeds such as Thistle, Dandelions, etc.

    http://www.bluebooktor.com/Library/...abel\L47578.PDF

    This is pretty cool stuff.

    Steve


    Steve, what's that cost? Looks like ornamental Transline.
    Clopyralid is wonderful stuff.
     
  9. Tordonista

    Tordonista LawnSite Member
    Posts: 36

    Oh-and---
    Round-Up on Canada Thistle, however applied, is a waste of time and money.
     
  10. Scraper

    Scraper LawnSite Bronze Member
    Posts: 1,656

    I can't say enough about how well Lontrel performs. At first I was hesitant as I believe I paid about $150/quart, but was money well spent as I was able to apply over many of the ornamentals in a clients landscape. It was a new planting and the thistle was so thick you would have thought it had been neglected for years. After two applications, control was achieved. This year with mino\r spot treatments no problems. I actually used "over top" liriope with no ill effects. I in no way condone this as they are not listed, but had no choice and took the chance.
     

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