Q.

A.

While Dual can break down fairly quickly when left on the soil in the sun without rain or incorporation, most other pre’s can sit there for a very, very long time. About the only other exceptions are the products with very high vapor pressures, including Trifluralin, Sonalan, and Eptam.

Q.

A.

Try to keep it as shallow as possible. Most products are shoot inhibitors, and most don’t move much in soil. Ideally, I’d like to see tillage done at 4 inches deep or less. However, the products I just mentioned that have high vapor pressure will become a gas in the soil and move upward to some degree. That’s why you can till deeper when using Trifluralin, Sonalan, and Eptam.

Q.

A.

We prefer a field cultivator, but almost any shallow tillage tool can work. We don’t like disks or plows because they often bury the herbicide.

Q.

CAN ALL SOIL-RESIDUAL HERBICIDES BE INCORPORATED?

A.

Absolutely. You may have been told otherwise in the past, but that was likely only because someone worried you would bury the herbicide too deep.

Q.

ARE THERE ANY TRICKS TO TILLAGE SUCCESS OR ANY WATCHOUTS WHEN TILLING IN THE PRE?

A.

To avoid streaks, make sure your hardware is not worn. For example, on our field cultivator we need to make sure that the sweeps are still wide enough so we have overlap from one gang to the next when we’re tilling. In other words, I want every inch tilled with no gaps. Also, drive fast. The faster you go, the less chance you’ll get too deep. Finally, nose-dive the implement. Herbicide goes in at roughly half the depth of your tillage tool. If we’re 3 inches deep with our field cultivator, that means most of the herbicide is in the top 1.5 inches. However, if the back of the machine is deeper than the front of the machine, you will continue to till deeper and push the herbicide further into the ground as the machine passes each area of soil. By having the front end slightly deeper than the back, you prevent this from happening, and your herbicide never gets any deeper than your target level.

Q.

AM I AHEAD TO SPRAY MY PRE BEFORE OR AFTER PLANTING? CAN THE PLANTER MOVE MY HERBICIDE OUT OF THE ROW IF I SPRAY IN ADVANCE OF SEEDING?

A.

Many people fear that the planter will kick the herbicide out so far that there will be poor weed control down the center of the row. I’ve only seen this once in my life, and I’m pretty old now. Typically, the planter pushes the soil out a little bit; but then it pulls it back in, and weed control is unaffected. The reason I recommend spraying before planting is two-fold. First, you get the work done, so you don’t have to worry about that job later on. Second, you’ve got a better chance for the herbicide to work great. The earlier you spray, the more time you have for rainfall. The more rain, the better herbicide uptake you’ll see in your target weeds.

Q.

HERBICIDES ARE EXPENSIVE. CAN I GET BY WITH ONE MODE OF ACTION AND/OR A LOW USE RATE?

A.

If your post-emerge herbicide can clean up every single weed, you don’t need to count on your pre as much. However, let’s say you’re raising soybeans. The 3 Pre’s we often talk about offer the least expensive and most effective weed control, and you can’t use any of those post-emerge. It’s important to look at total cost, but since most herbicides are less expensive than they were 20 years ago and crop prices are double what they were 20 years ago, the return on investment is usually quite good, especially with the pre-emerge herbicides.

Q.

HOW MUCH RAIN DOES IT TAKE TO ACTIVATE THE HERBICIDE?

A.

Activation gets the herbicide started, and it takes almost no rain for that to happen. To make a pre herbicide work fantastically well, I’d like to see 3 inches of rain within a week or two after application. I know that’s a lot, but my hope for you is 100% control, not just 90% or 95%, and it may take up to 3 inches to achieve the very best results.

Q.

IF I WANT TO GO WITH JUST ONE HERBICIDE APPLICATION, SHOULD I DO IT PRE OR POST?

A.

Probably early post, but thinking you will achieve perfect weed control and top yields with just one shot of herbicide per season is wishful thinking. I’ve never seen it yet. Sure, you can save a trip by spraying once – and I’m not saying your yields will be a disaster or your weed control will be horrendous. My point is simply this. If you let weeds come up before you spray, that likely negatively impacted your yield a little bit. If you let just a few weeds go to seed, you will have more to kill in the future. Keep in mind, waterhemp and Palmer can put on 1 million seeds per plant, and kochia can throw 30,000. Weeds hurt yield both now and in the future. You don’t necessarily have to spend more on herbicides, but when you split apply you have two opportunities to kill weeds and you typically have cleaner fields both this year and next year, not to mention slightly higher yields in most cases.

Q.

HOW CAN I MAKE MY PRE-EMERGE HERBICIDE TWICE AS EFFECTIVE?

A.

At the outset of this article, I made a wild claim about getting your pre to work twice as effectively. I don’t know if your prior application method was hurting the performance of your pre-emerge herbicide, but here is my advice if you want the absolute best results on your farm this spring. I encourage you to use a full rate of at least two or three residual herbicide modes of action that are fantastic on your target weeds. For example, if you are after waterhemp, Palmer, and/or kochia, ALS chemistry is not a good choice. Next, lightly incorporate your herbicide at the highest speed you can possibly run – 7+ mph. While you don’t have to till your herbicide in, it will work better and with less moisture. After that, prayer is always helpful because having at least some rainfall is always better than none. If you aren’t going to incorporate your pre, I recommend spraying pre-plant, and hopefully you’ll get some good rains within a week or two after that.