In recent years no-tilling has become a blessing for farmers because of its benefits such as less soil erosion, less labor and fuel resulting from no plowing and the fact that soybeans and corn have been genetically engineered to resist applications of glypsophate (Roundup) used for weed control.
The less costly and environmentally friendly benefits of no-till methods of farming have recently come under threat with the rise of several glypsophate-resistant weeds with the first resistance discovered in Delaware in 2000. Now according to a New York Times article from 2010, there are at least 10 glypsophate-resistant weeds in 22 states affecting millions of acres that may dampen farming enthusiasm for crops genetically engineered to survive over-the-top sprays of the chemical.
Two glypsophate-resistant weeds in particular are threatening the no-till system in that they have a fast growth rate, starving crops such as cotton, soybeans and corn of much needed water and nutrients.
Primarily in the south, the enemy is Amaranthus Palmeri or Palmer Amaranth which was once cultivated and eaten by native Americans. This species has developed high resistance to gylpsophate beginning in 2006 as the glypsophate has killed off the susceptible strains with only the stronger glypsophate-resistant strains remaining. As one farmer in Georgia stated that if this weed infestation is not stopped, it will be to cotton what the boll weevil did in the early 20th century.
In 2014, the Environmental Protection Agency denied the Texas Department of Agriculture’s request to spray propazine on 3 million acres of cotton being “choked” by the Palmer Amaranth because of the risk of contaminating drinking water.
Northern states like Ohio are not immune from the Amaranth pestilence as it is now found in 16 Ohio counties due to the importation of manure from the south to be spread on fields. The other no-till threat weed is Conyza Canadensis known as horseweed or mare’s tail. Mare’s tail resistance to glypsophate was first noted in Ohio and Indiana in 2006 and since has become more widespread. Seeds in a number up to 200,000 for a mature plant of 6 feet or more are spread by the wind. These fall dispersed seeds germinate immediately and form a rosette of leaves in which the majority of the seedlings survive the winter.
Then in April and May, this rosette begins to bolt with warmer temperatures and the longer daylight duration. Cutting off the weed can create more branches for seed heads so that hand pulling or tillage is the only effective control besides herbicides. Applications of glypsophate alone on mare’s tail while ineffective for control, are useful when combined with 2, 4-D or 2-4D Ester with the latter chemicals being less environmental friendly than glypsophate.
Stark County farmer, Ron Hill, does not suffer from infestation of mare’s tail in his soybean fields as he prefers to plow them before planting thus eliminating the overwintering mare’s tail. Ron’s example of plowing in spring eliminates the fall germinated mare’s tail and the seeds germinating in spring. His example may be repeated over millions of acres thus negating some of the environmentally friendly benefits of the no-till system and resulting in higher production costs for farmers now relying primarily on the genetically modified crops of soybeans and corn.
In summary, glypsophate-resistant weeds such as the Palmer Amaranth and mare’s tail pose a severe threat to the no-till farming method of recent years as more of the noxious weeds take hold. The lower cost of no-till farming and the environmentally benefits of this method are under siege and with its possible abandonment may lead to higher food prices and more pollution of waterways from soil erosion and application of various herbicides to control weeds.