Before the advent of Roundup Ready Soybeans, Roundup is a non selective contact herbicide, the herbicide choices for weed outbreaks were limited. a product that was effective for us in past was Cobra, but it made the soybeans look very sick. We were some of the early adapters of no till in our area so a lot of trial and error in crop rotations took place and herbicide carryover and rotation restrictions are always a concern. After experimenting soybeans were found to be a good fit between grain sorghum and wheat. Rotation restrictions also puts some limits on the preplant residual herbicide choices and sometimes also on the herbicides we can apply over the top during the growing season. This makes RoundUp, active ingredient glyphosate, very attractive since there is no rotation restrictions following application of it. Using Cobra as an example, it has a 12 months rotation restriction to wheat, we typically seed wheat within less than a week following soybean harvest so if we used it we would have to either idle the land for a year or plant another crop the following spring.
We plant corn that contain both herbicide tolerant and insect resistant corn on irrigated fields. Initially we were reluctant of planting both Roundup Ready soybeans and corn in the rotation, because of the chance of developing herbicide resistance in weeds. Insect resistant corn was very appealing because it controled corn borers without the need for organophosphate insecticides, these were a very effective class of insecticides that killed every insect present in the applied area and has been banned a few years ago. With GMO corn we have targeted insect control and according to USDA-ARS researcher Dr. Jonathan Lundgren's has found a tremendous amount of predator insects present in fields of Bt corn. Dr. Lundgren feels that farmers might want to consider saving seed expenses by reducing the amount of Bt corn they plant because of the effectiveness and widespread use. The last few years we've planted corn with stacked traits to obtain the insect resistance we feel we need in the corn varieties that best suit our irrigated fields. With so many different traits available care is taken to note which fields are planted to herbicide resistant corn if follow up weed treatment is needed, all of the necessary refuge for the insect resistant traits are planted first. We plant seed from all three major GMO technology companies, each Bt corn is slightly different, we try to match the seed variety that's best suited to the field.
Our non irrigated corn, in the years we feel that our higher quality land has adequate moisture to raise a corn crop, we plant heebicide resistant corn. Insect resistant traits aren't necessary because of time between possible corn crops, diverse rotation and the physical distance to other corn fields and it reduces seed expense on a crop that might fail. sometimes seed dealers will give us a bag or two of seed that they think is ideal for those fields that contain insect resistant traits.
For the last few years in our soybeans were seeded them in 15 inch rows. This narrower row spacing allow the plants close the rows earlier and shade out late germinating weeds. I'm wanting to try this on corn also, the combine attachment for corn has to match row spacing so this is an added expense for a specialized piece of equipment. This past year in a weedy corn field I noticed the narrow strip where the fertilizer is applied next to the corn row was largely void of weeds. I think with narrower rows combined with how we apply fertilizer might decrease weed pressure and the possibility of a late herbicide application.
Sorghum and sunflowers are such a minor crop and small market, seed companies didn't see enough market for the time and research to develop GMO traits for them. After the export challenges faced by corn and soybeans GMO wheat research was essentially shelved, there are rumors that research will resume in the near future. These crops in addition to soybeans are what we grow on our non irrigated land, most of our acreage isn't irrigated.