Crabgrass?

timtsb(7a)July 5, 2014

I know this is the most basic of questions, but as a first time homeowner I want to make sure I'm identifying this correctly and do the right thing to fight it. I believe it to be crabgrass, correct? If so I have two questions:

What did I do wrong? I put down Scotts Turfbuilder with Halts crabgrass preventer in the spring. Up until a couple weeks ago, I hadn't seen any crabgrass in my lawn, now it's popped up in all the weak spot of my lawn; mostly near the edge of my driveway and in a few spots where trees were removed last year and the grass won't grow. Should I have done two applications of Halts?

What do I do now? I know it's too late for preemergent...do I still put some down to prevent new growth AND apply a post emergent? I spot sprayed with weed b gon today...do I need to be more aggressive and put something over my whole lawn?

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dchall_san_antonio(8 San Antonio)

That is crabgrass. What you did wrong is either 1) you watered too frequently and not deep enough, or 2) you let Mother Nature rain too frequently. Or if this is a fescue lawn, you should have overseeded last fall to "densify" the turf and help keep the weeds out. What is your watering schedule? How often and for how long? Also what kind of grass do you have?

There is a product you can spray, but I never get that stuff so I don't pay any attention to the cures. You would not have to search too keep on this forum to figure it out. I'm sure someone will help with that.

    Bookmark   July 5, 2014 at 7:39PM
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timtsb(7a)

I actually just turned my sprinklers on in the past couple weeks because it's been hot with little rain here. At most I water 3 days a week - Mon, Wed, Fri.

This is a brand new fescue lawn seeded last September.

    Bookmark   July 5, 2014 at 8:32PM
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dchall_san_antonio(8 San Antonio)

You're watering too often. I watered a small part of my near-desert lawn on June 27th and once on April 3rd. Most of my lawn has not been watered since last year sometime, except for the occasional 1/2-inch of rain.

Mine is obviously not normal. Normal, based on 12 years of reading here and listening to some pretty good experts, normal in the hottest summer heat is once per week. In Phoenix that means once every 5 days with dry heat in the low 100s. In The Garden State, that probably means once every 10 days.

By allowing the surface of the soil to dry out completely before you water again, the crabgrass seed cannot germinate. Crabgrass seed apparently needs exactly what you're giving it, thin turf, full sun, and frequent watering.

    Bookmark   July 5, 2014 at 9:26PM
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botanicalbill(9b SWFlorida)

That looks more like goosegrass and is more difficult to get rid of. Most crabgrass killers will not touch this stuff.

The two grasses that get confused with crabgrass the most are dallisgrass and goosegrass. Most crabgrass killers will not touch these two.

Here is a link that might be useful: goosegrass

    Bookmark   July 6, 2014 at 11:48AM
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joneboy(7)

Timtsb, it's hard to say where you went wrong. You should not need two apps of pre emergent for summer annuals in NJ. Here are the rules for applying a pre emergent. 1. Spread at the right time (for NJ around the beginning of May) 2. Use the correct rate. A good idea is to spread at half rate in two directions perpendicular to each other. 3. Water in pre emergent immediately with half an inch of water, rain or irrigation.
If you used the Weed B Gone with the active ingredient Quinclorac it will take two apps. to get rid of the crabgrass.I would not reapply a pre emergent now. Use your Weed B Gone to control any crabgrass that pops up this summer and reseed your thin areas late summer/early fall.

    Bookmark   July 6, 2014 at 5:23PM
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polyguy78(z8OR)

Definitely crabgrass and not goosegrass ( aka Silver Crabgrass ). With granular products applied by drop spreader it's very easy to get 'skips' and miss areas. Your timing or the amount of water applied might also have a led to some issues. Rarely does any irrigation system apply water evenly so that may be the source of the problem. Another issue can be applying the pre-emergent too late. For virtually all pre-emergent, once the seed is germinated the herbicide will NOT work. The comment on the use of Quinclorac is a good one. I'd suggest taking a look at the product label on line prior to purchase to determine if it's suited for your area and that the timing of application is appropriate.
There's also some comment on irrigation. Bottom line, each site will have it's own irrigation needs. The key is to learn from your lawn. A tall fescue lawn will quickly exhibit drought stress symptoms as the leaves curl and turf color takes on a dark, stressed appearance. Typically you'll first see the drought stress in isolated areas where either insufficient water is applied or soil might be more shallow or compacted. Generally we refer to these areas as 'hot spots'. If water is not applied, the areas of stress will grow larger and if not irrigated, the most affected turf areas may die out. Bottom line, observe the lawn and learn which areas are likely the first to become water stressed.
Getting back to the crabgrass, if you've only small areas and hand weeding isn't extreme, remove the plants. A sharp serrated knife and cut the plants off slightly below the soil surface. They'll not come back as they've no below ground rhizomes to recover with. If you choose not to weed, fortunately the grass is an annual and it will die out with the first hard frost. Just be ready next spring. Ideally at least 2 weeks prior to germination. Hope the comments are helpful........PG78

    Bookmark   July 6, 2014 at 7:15PM
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timtsb(7a)

Thanks for all the great info.

Regarding the watering schedule - I had a feeling I was watering too often. So many neighbors started watering well before me when I knew the soil was still moist. Many of their lawns are a nice dark green color and mine had hints of yellow and, in the backyard where I kept the existing lawn instead of planting new, even brown (not brown spots, just brownish grass mixed inr). I know where the spots are that this is happening because of trees we had removed. For the rest of the lawn, I figured it was because my pH was a little low, so I applied the recommended amount of lime (Mag-I-cal), but have seen little change. So then against my better judgement I assumed I needed to follow the pack and water the lawn...still not much change. I'm going to put down some Milorganite hoping the Iron will help.

Regarding the pre emergent - I was so paranoid that crabgrass was going to take over, I think I put it down a bit too early (March 23). I made a rookie mistake and was paying attention to air temps, not soil temps. It still seemed to do it's job, though, up until now.

I used the Weed-B-Gon with crabgrass control which does have quinclorac. I sprayed it Saturday, mowed about 24hrs later and then sprayed again. Maybe I will take the time to pull it...I don't know that I have the patience to wait for the Weed-b-Gon to do it's job.

    Bookmark   July 7, 2014 at 11:01AM
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timtsb(7a)

Does the fact that my front lawn is full sun affect watering schedule at all? The parts of my lawn that are partial shade are growing much faster and greener. Anything I can do aside from planting a tree to help the full sun area? I mow 2.75" high. My mower has two higher settings, 3.25" and 3.75", should I be mowing higher?

    Bookmark   July 7, 2014 at 12:22PM
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SoCalDawg

C'mon guys....watering once a week? My Marathon II "lawn" would turn yellow and brown in no time and here in SoCal we're getting temps in the low 90's. But for the sake of argument, how long should these once-a-week waterings be?

Don't get me wrong, I'd love for you to be right!

Mike

    Bookmark   July 8, 2014 at 12:01AM
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