A grower called me the other night and said he was getting ready to plant corn and found out that two of the herbicides he used last year in soybeans had 10-month plant-back intervals. He wanted assurance that he would be okay if he shorted that interval a little. Those restrictions are not an exact science, but they are on labels for a reason.
The call reinforces my belief that we have a steep learning curve for growers to get back up to speed on soil residual herbicides. A lot of folks are talking about residual herbicides like they are a new discovery. There is a generation of us (weed scientists, farmers, consultants, sales reps) who once had to depend upon them — especially in soybeans and cotton. They are being rediscovered now as weed control is rapidly going back to the 1980s and earlier in these two crops.
If you are trying to control resistant Palmer pigweeds in Roundup Ready crops, the herbicide technology is back to the 1980s and early 1990s. We had to depend upon residual herbicides then. They are great when they work — and I am an advocate of using them again. However, if it does not rain on a pre-emergence herbicide, it does not work — at least not on the first flush of weeds. You often only have three to five days to beat a flush of pigweeds with a rain. Some of this can be overcome by stacking the residuals.
If it rains too much, or at the wrong time or the weather turns cold and wet, they can injure or sometimes kill the crop. We used to deal with a lot of crop injury from herbicides like Sencor or metribuzin-containing products in soybeans and Cotoran, fluometuron and diuron in cotton.
Some herbicides can carryover and have plant-back intervals. This complicates the use of Flexstar, Reflex and Prefix in Roundup Ready soybeans if you are rotating crops. None of these are negative comments. It is simply reality with soil residual herbicides and some of the reasons we quit using them when better technology came along in the mid 1990s. If we have to go back to 1980s technology something is wrong with the picture.
I recently heard a speaker comment that 70 percent of our cotton this year would have hoe crews in it. He was talking like that was an okay thing! For six years of my life I attended a school with a split summer vacation. That meant we got out earlier than other schools to chop cotton, went back to school after lay-by, then got back out to pick cotton in the fall while other kids were back in school. Folks, chopping cotton is not okay! That is 1950s and earlier technology and something is wrong with that picture as well.
It is crazy to hear people talking about “where can you buy a good hoe?” I agree the hoes my wife has bought recently for the garden are sorry — the metal is sorry, the handles break and the heads fly off. They won’t phase a 2-inch pigweed! There is talk of companies going in business to custom build hoes to meet the demand for good hoes in cotton. If we have to go back there, my generation of weed scientists has failed miserably! My national society, the Weed Science Society of America, does not want to talk about herbicide trait rotation! Is hoeing better?
We are going to do what we have to in order to survive the herbicide resistance onslaught. Some of it will be by using residual herbicides; some of it may be with changes in cultural practices, and, yes, some may be with hoeing for a while in some cases. However, there is something wrong with going backwards.
Unless we can get a technology like LibertyLink in the mix on a widespread scale right now, we are going to continue to go backward. I strongly believe Ignite is the only single herbicide right now that has a chance to turn the tide back in the right direction. If it is properly utilized it can be a key to saving Roundup Ready and be a viable technologies for years to come.
I have never seen a technology as good as LibertyLink that so many are so reluctant to use. That is no sales pitch. Just look at where we have gone the past three years without it. If we continue to abuse Roundup Ready as we are, you will eventually plant LibertyLink crops out of necessity. This means a short life for another great technology.
If we continue using up technologies one at the time, we are truly going to need more companies manufacturing good hoes.