Plot rotation...what next?

[yoderjac]

I love how you always say, "Marestail that is naturally resistant to glyphosate." How is that possible? Academia says it's from overuse / misuse of glyphosate, such as using a half rate to "supress clover."

Easily. Different plants have different resistance levels to herbicides. While there is a process where particular weeds can become more resistant to specific herbicides. Gly resistance is a perfect example. Within any population, there are different levels of resistance. When herbicides are used individuals in the population that are most susceptible to the herbicide will be killed and won't reproduce. The most resistant individuals in the population will be hurt but many will still reproduce. Over time, the population in general of that weed becomes more and more resistant to that herbicide. Low application rates, as you suggest can accelerate that process.

If there was no natural resistance to the action of a particular herbicide in a particular weed population, none would be created by use. The use of herbicides simply becomes an environmental factor that the natural selection process responds to.

As it turns out, I'm not in an area where there is a lot of local ag. Within 3 miles, the only agriculture is pasture land that generally is not sprayed. In my case, we thinned and burned a pine stand. The marestail seed had been in that soil bank for over 20 years, before gly-resistance was well known, even in large ag areas. The marestail that grew up in those thinned/burned pines went to seed and infiltrated our fields. The next year, we had more marestail than beans in our RR soybeans. This was not marestail that was growing in our fields getting sprayed with gly year after year. It all happened at once.

I quickly realized that continuing to plant RR crops would make the situation worse. So, l started spraying it with 24D and switched to planting buckwheat. Last year I experimented with a mix of Buckwheat and Sunn Hemp. I'll be upping my planting rates, but I plan to continue to plant them rather than RR crops going forward. This means significantly less gly uses for me.

So far, even with the occasional use of light application of gly on clover fields. We have no weeds that were previously susceptible to glyphosate that have become resistant. Fingers still crossed....


Thanks,

Jack

 

[jsasker007]

I think swat was right with the mis-use. People trying to get by a little cheaper and not believing the manufacturers suggestion---they did the testing and figured out proper amounts and then the public has to think that they know more about it than the manufacturers. Happens way too much in my opinion. Common sense just isn't very common anymore.

 

[yoderjac]

I think swat was right with the mis-use. People trying to get by a little cheaper and not believing the manufacturers suggestion---they did the testing and figured out proper amounts and then the public has to think that they know more about it than the manufacturers. Happens way too much in my opinion. Common sense just isn't very common anymore.

There is no doubt that what SWAT said generally occurred and made weed species that were previous not resistant to gly resistant. However there were always some weeds that were resistant to gly naturally. Marestail is one. While gly is a broad spectrum herbicide, not broad spectrum herbicide covers 100% of weeds.

Thanks,

Jack