are you guaranteed to have a weed outbreak if....

[Ric]

Originally Posted by Think Green

Skipster,
You make a great CPA........you like to crunch numbers.
I can't win with the likes of answering why my 2.3 gallons per thousand is applied!!! I hear that 5 gallons per thousand is enough also. Who is right?? Who is wrong??

Skipster must have an irrigation license because his numbers are straight from the book. In some areas, Golf course Greens keepers are give tight water budgets in ACRE INCHES. They must budget those inches of water through out the year. If you think Skipster is crunching number, You would go crazy budgeting a years worth of acre inches on a golf course.

In Edit: When I use Pre Emerge I insist it is watered in the first 24 hours. However there are two schools of thought on Pre emerge and CHEMICAL ROOT PRUINING. I am of the NO PRE EMERGE school. A thick health Lawn is the best method of weed control bar none.

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[Think Green]

Nothing wrong with being a numbers person!No harm intended.......no harm taken.
Thanks Skipster for your input.

[cgaengineer]

Originally Posted by Skipster

I'm not sure that your 3 gal/M carrier volume does much to move any product into the soil. To cover an acre in a half-inch of water takes 13,577 gallons. Assuming equal amounts of solids and voids in soil (not always an accurate assumption, I know), it would take 6,788.5 gallons of water per acre to move your PRE treatment a half-inch into the soil. Your carrier volume applies only 130.68 gal/A moves the product only 0.005 inches into the soil. Knowing that a heavy dew only adds a gallon to two to an acre, we can see that neither carrier volume nor dew contribute in any meaningful way to moving the PRE into the soil.

All that aside, I don't think that not getting water on this application is going to make it a total disaster. I've had many customers over the years that didn't water in their app and didn't get any rain, but still had fewer weeds than their neighbors. Sure, getting it watered in is the best scenario, and I think it's not too late to begin watering now.

You'll notice better control in the areas that don't have much weed pressure (thick, healthy lawn, not too wet nor too dry, right amount of sun or shade for what you're growing), but you'll have some weed breakthroughs (maybe not bad, but I think there would be some) in the areas that are more prone to weed problems (thin grass, overly shady or sunny, excessively wet or dry).

Your first paragraph is spot on...been telling these folks that pre applied at 1gal/k vs 5gal/k makes little difference...I've even posted the same math as you...the fact is, .5" of irrigation is a ton of water and an entire skid tank ain't even close to applying enough.

I run my gal/k low so that I get more coverage per tank...been working fine for me.
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[Think Green]

The mathematics is great for budgeting and monitoring a golf course, but definitely isn't practical in my apps. I can just see applying 1200 gallons per acre(hypothetically) for prodiamine or something equivalent. The main topic was wiped a little off the map....but agreed that if no water is obtained within a period, the product is rendered less effective. The chemical companies know of these variables and leaves a lot of room for error in application if not followed to the T.
I just talked to a customer today about a potential landscape tear out........the customer was shocked to hear how much water it will take in the winter to keep new plants alive. We are still in a drought and haven't seen a couple inches of water in a month of soaking rains. I will not plant shrubbery under these conditions right now, let alone their lawn is pitiful with broadleaf weeds. I can treat for the broadleaf weeds, and apply a preemerge for others, but without water in the near future, it will be touch and go with proficient weed control.
People think that turning on a lawn sprinkler for 15-20 minutes is all it needs when the temps are cooler. This customer makes all the decisions.....the husband does all the work and doesn't know what their GPM is from the faucet or the sprinkler. I told them how to figure it........and guess what!! His and her eyes rolled in their eye sockets. So then it was time for me to leave the estimate and get to the real figures.
I can't help but be pessimistic in situations like this...........all you can do is turn and walk away!!!after politely saying--" You can't have total beauty without watering it!""

[greendoctor]

The amount of water needed to properly activate an application, be it fertilizer or preemergent is the reason why I have nothing to do with non irrigated lawns. Not if it does not rain an inch per week. Raining 10" in a couple of days with no rain for the next several months does not count.

[greendoctor]

Originally Posted by cgaengineer

Your first paragraph is spot on...been telling these folks that pre applied at 1gal/k vs 5gal/k makes little difference...I've even posted the same math as you...the fact is, .5" of irrigation is a ton of water and an entire skid tank ain't even close to applying enough.

I run my gal/k low so that I get more coverage per tank...been working fine for me.
Posted via Mobile Device

You once asked me how to get even applications using less than 5 gallons per 1000. Low volume treatments work fine as long as there is sufficient water in the period after the application.

[Think Green]

Originally Posted by greendoctor

The amount of water needed to properly activate an application, be it fertilizer or preemergent is the reason why I have nothing to do with non irrigated lawns. Not if it does not rain an inch per week. Raining 10" in a couple of days with no rain for the next several months does not count.

Good quote Doctor!!
I wish my customers would absorb information like this and take warning to the truth.

[Skipster]

I hope I didn't come off as dismissive in the numbers post -- I just wanted to be clear that no reasonable carrier volume is going to move a product sufficiently into the soil.

PRE applications are generally thought of as benefitting from a higher volume because using more water could help move the product down through the canopy, so it's not exposed to as much volatilization or photodegradation pressure as it owuld be if it were on the plant leaves. But, how much difference does it make? I don't know.

So, when deciding on your spray volume, I would think that the best route to take is the one that gives you the best coverage and makes the most sense for you. If you can't get a day's worth of lawns sprayed with your tank size at a particular volume, see if you can use a lower volume.

I don't think that one volume is necessarily better than another. You'll just want to make sure that you get good coverage with whatever volume you use.

[greendoctor]

Originally Posted by Think Green

Good quote Doctor!!
I wish my customers would absorb information like this and take warning to the truth.

Part of my terms of service with customers includes access to their irrigation controllers. I set their controllers to apply an inch of water per week average, with decreases during the short daylight time of the year. Try to flood the lawn or dry out the lawn and I am out.

[Think Green]

Skipster,
You made me think in a different spectrum. I have been monitoring irrigation systems during this drought to keep the lawns alive and not flourishing. On most......7 day intervals, I wasn't monitoring the output in gallons per acre. The customer didn't want any dead grass............so that was the goal.

No harm at all.................this is why I came to this forum.