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Are there any issues with preemergents in hot weather?

Discussion in 'Homeowner Assistance Forum' started by nolo, Jul 23, 2018.

  1. nolo

    nolo LawnSite Member
    Messages: 101

    It's has been in the 90's lately. I called Sta-green (Pennington Seed) to ask about spreader settings for crab ex. Crab ex is a dimension type product in granular form. The lady was saying that it can't be applied in weather over 85 degrees. I wasn't sure if she was confusing the product with a weed and feed with atrazine in it. Are there any issues with using dimension in hot weather?
  2. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 15,470

    Nolo, I think you are right. As a granular, I do not see any issues with a granular Dimension product if the temperature is over 85. Do you want post-emergent control?
    It is very late, however. Why not wait until next spring?
    As a second pre-emergent or split application June would be about the proper time.
    Myself, I would not expect much effect from the Dimension as a post emergent. Only effective up to the three leaf stage--and that is probably optimistic.
    Actually, I have a test for this. Dimension granular at maximum rate on a patch of crabgrass on July 22, 2018. I will check on the results in a couple hours. Is the crabgrass supposed to turn brown? Distorted leaves? Just stop growing?
    hort101 likes this.
  3. takervader

    takervader LawnSite Senior Member
    from Alabama
    Messages: 349

    I dont know of any problem using a preemergent in the heat, unless its extreme heat and the grass is showing drought stress I wouldnt hesitate.
    hort101 likes this.
  4. OP

    nolo LawnSite Member
    Messages: 101

    I do want some post emergent control, but it isn't that necessary. I'm concerned about getting another explosion of crabgrass. I'm not sure if it is possible this late in the year, however. I didn't think I would need to apply this many apps of preemergent. I applied 1 full app in late February of prodiamine. One app in mid May of Dimension. I'm thinking about hitting it again with dimension and then prodiamine in late September early October.

    Let us know your results on how it did as a post emergent.
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 15,470

    So far, no results from the post-emergent application of fert with Dimension granular. Crabgrass was at about the 4-leaf stage. I used about 8 pounds--double the usual 4 pound rate--still within label rate for short cut turf. Photos and details later. 8 sqft.
    Is the crabgrass supposed to turn brown? Wilt? just disappear?
  6. That Guy Gary

    That Guy Gary LawnSite Silver Member
    Messages: 2,413

    I'd double check the label on the granular, if I remember correctly the window for control with granular is a lot smaller.

    Like the zero tiller stage if I'm remembering correctly.
  7. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 15,470

    Gary is right, you need to apply it a bit heavier to get post-emergent effects. And heavier still if the crabgrass is bigger.
    I used 30-0-3 with .137 % dithiopyr. Used one ounce on 8 sqft.
    I applied about .5 pound of dithiopyr per acre. If my calculations are correct.
    So far no visible effect on the crabgrass.

  8. That Guy Gary

    That Guy Gary LawnSite Silver Member
    Messages: 2,413

    I thought the liquid had a broader range but I just looked at that label and it says pre tiller (5 leaves or less) as well.

    It's all just theory but I think it offers some early control because it's a root growth inhibitor and crabgrass isn't the best rooting grass out there. While other plants seem to prioritize some root development ahead of vegetative growth when they sprout crabgrass seems to like to do it backwards.
  9. That Guy Gary

    That Guy Gary LawnSite Silver Member
    Messages: 2,413

    I think I sprayed it all but I'm going to check the cabinet tomorrow to make sure, if there is still some 2EW in there I'll mess around with it while I'm out cleaning up the mess a few scalpers have made at some lawns I treat.
    Walker56 likes this.
  10. CLJ1020

    CLJ1020 LawnSite Member
    Messages: 2


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