# Pre-Emergent Timing and Which Type?



## Legz (Feb 9, 2019)

Hi Everyone,

New to lawn care and to the forum and I hoping to get some advice on pre-emergents. I will be putting a post together in the Journals section for my lawn situation as a whole but I wanted to get to this question out there first. Long story short I moved into my home at the end of last summer and crabgrass had run rampant. Due to my inexperience at the time I didn't know the importance of seeding in the fall and missed that opportunity. I found the LCN over the winter and have been working on putting together a plan to make my lawn green again.

Which brings me to my pre-emergent dilemma. Historically, in my area (Durham, NC) soil temperatures reach the mid-50s in late March so I thought I had some time to keep planning for my pre-emergent application. However this last week we had some very warm temperates (4 days in a row that were 70-80 degrees) so soil temperatures have gotten into the 60s already with the 5-day average being 55 degrees and I feel like I need to get some pre-emergent down stat. Things cool off a bit in the coming week but after this weekend it'll still be relatively warm:



I would have liked to have gotten the pre-emergent down during the week, but with work and it being my first time using a spreader I was hesitant to do so because I was hoping to practice with some Milo first, but I don't want the crabgrass to be an issue again. So, should I go ahead an put down pre-emergent this weekend? And if so, which would be my best option?

-Home Depot has a 0-0-7 that is with Pendimethalin or a 19-0-7 with Dimension
-Lowe's has a 0-0-7 with Dimension

Thanks for any help!

Legz


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## g-man (Jun 15, 2017)

My choice would be the Lowe's 0-0-7 with dimension.

It doesn't have nitrogen, so you are not pushing for grow too early in the spring.

Other members applied it last weekend for your area/weather.


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## Legz (Feb 9, 2019)

Thanks, g-man! Pre-Emergent purchased and will be going down tomorrow.

The label says to apply at a rate of 3.3lbs/1k sqft. Max of 6.67/application and 20lbs/year. Since this is my first application and there was quite a bit of crab grass in the fall, should I bump up my rate a bit? To like 5lbs/1k sqft?


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## g-man (Jun 15, 2017)

I will need the label to ensure I do the math right. At least I will need the % of active ingredient per weight.

I would suggest a split application, half rate now and half in 6-8weeks. This extends the protection. This is assuming you are not planning to renovate your lawn this year.


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## Legz (Feb 9, 2019)

% looks to be .172 Dithiopyr in a 50lb bag. I can send pictures of the label if need be. I've been searching for an electronic version of the label but have failed at being able to find one.

No plans to renovate. Currently plan is treat what is there and seed in the fall, see how things look come next spring and go from there.


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## 440mag (Jan 29, 2018)

Welcome! I'm 2-1/2 hours West of ya, in betwixt Hickory and Morganton and you sound like a mirror image of me when I found this WONNNNNNNNNNNDERFUL resource and treasure trove of extremely experienced - and methodical - practitioners. I say that as I was kinda caught in a cycle of RE-Action, responding to the dilemma of that part of the year and it wasn't long before I was (and now always am) thinking 6-9 (even 12) months AHEAD of today's date on the calendar, ha-ha!*

That Lesco 0-0-7 ("Dimension", IIRC) is great stuff Spring and Fall as is g-man's counsel. (I have to be extremely careful with that Lesco 19-0-7 as I have had it burn spots terribly, either because my yard is really a cliff and making turns with a rotary spreader while traversing a steep slope can result in a momentary too heavy a throw in a spot OR (more common) rain will push the 19-0-7 into small piles on the hillside and "burn, baby, burn" spots is what I got to look at, sometimes for many, many months. (Because of fungus problems in our area (more in that later!) I only apply products containing significant amounts of nitrogen in early April (on a rare occasion late, late March) and late Oct and Nov (on rare weather occasions early, early Dec)

Hopefully, your lot is much (much!) more level than mine!

In our bit of a transition zone I go with the mid- to heavy- rates on the bag label and take the advice of those here and do split app.s

Our lawns sound similar as far as neglect before we moved in and I lost a lot of time to weeds besides crabgrass by using the light rates recommended on the bag, even when split app'ing. You never want to go beyond the maximum annual rate but, even going on the heavy rate appearing on the bag label I've never come close to a maximum rate of any product (even if I did I would simply switch to a different pre-emergent for the remainder of that 12-month period)

*Post script: So, thinking months ahead now, and living in the Piedmont of a southern state, you may want to start thinking about fungicides. "Thinking about" as in actually procuring you at least two different Mode of Action (FRAC) fungicides. *CHECK OUT THE "Fungicide Guide" THREAD and start educating yourself on the handful of most common fungal diseases in our area and about fungicides in general.* Online shopping (DoMyOwnPestControl, Solutions Pest & Lawn,metic. are terrific online vendors) may be your best bet and now is a good time to get a minimum of two different MOA fungicides as some products get in short supply once warm humid weather hits much of the nation and there have been "runs" on certain of the more-effective products. (Note: Occasionally, well-intentioned folks who live "outside the Triangle" will tell you "fungicides aren't necessary with proper cultural practices" and for the most part they are right - particularly about WHERE THEY LIVE. Do yourself a favor and at least have some fungicide on hand and, if you never need it, heck, I'll buy it from you. But, ask any of the other members here in N.C.; you're gonna be glad you have it when you do need it! 

Welcome again!


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## Legz (Feb 9, 2019)

Thanks for the information Mag! I am definitely glad I came across this forum, it has given me plenty of reading material. Nice to have people in the same area as well for regional advice such as with the Fungicides. My research so far hasn't touch on that at all so I will be sure to add it to my list and dive into that deeper!

I am trying to wrap my head around the idea of the split rates and the "strength" of the application and making sure I'm understanding it correctly:

The bag recommends a rate of 3.33lbs/k which it says provides 3-5 months of coverage. So I can either do 1 app at that rate or split it up into two apps at some determined amount(be it ~1.67 lbs/k each or 2.33 lbs/k first app and 1 lb/k 2nd app)? Would the single and split both provide the same 3-5 month coverage? Just with the split it will provide a 'jolt' 6-8 weeks into the coverage period? Or does the split add 6 weeks (if I were to apply the 2nd app 6 weeks after the 1st)?

Since the bag says the maximum per application is 6.67 lb/application. If I were to hypothetically up my rate to this maximum with a single application, would this increase the duration of the coverage to over 5 months? Or Does it make the potency stronger but will still only last 3-5 months? Or both, extend the duration and potency?


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## g-man (Jun 15, 2017)

I'm going to give you the short answer since I have to leave the house soon and I want you to have the info this am. This thread shows the rational for the 0.25ai/acre rate. Ai= active ingredient. It also shows the math in detail. https://thelawnforum.com/viewtopic.php?t=7246

(0.00575 lb of ia/ksqft) / (0.00172 lb of ai / lb of product) = 3.34lb of product/ksqft to get 0.25lb of ai/acre rate

Therefore their recommendations for 3.34lb/ksqft is a 0.25ai/acre rate. If you only do that rate now in February, you will start to lose protection in May/June (around 51% control using the treatment 12 from the Purdue report). I suggest you do another application (aka split) at 3.36lb/ksqft in May, which should cover you until September/October.


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## Legz (Feb 9, 2019)

Got it! That makes sense! Thank you!


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