Ragweed is both an invasive pest to many crops and an irritant to the human respiratory system. For control of this weed, herbicide programs and cultural control both offer effective management. Depending on your particular home garden circumstances, you can avoid damage to your prized plants with proper care and attention.
Common ragweed (Ambrosia artemisiifolia) is a summer annual weed that grows to a height of 3 to 6 feet, according to the Purdue Extension. Commonly referred to as annual ragweed, hayfever weed and wild tansy, this weed displays green to pale red hairy stems with green lobed leaves that measure up to 6 inches in length. Ragweed also produces spikes of flowers in a green hue that changes to yellow-green.
Ragweed is an extremely competitive plant that thrives in poor conditions. Ragweed has the ability to inhabit soil for up to 30 years before germinating, according to the University of Illinois Extension. Due to the sturdiness and aggressive nature of this weed, ragweed disrupts crops such as corn and soybeans in no-till areas. Herbicide control is necessary to prevent damage to crops and yield depletion, according to the Purdue Extension.
Practice caution when handling ragweed or if you suspect it has cropped up in your landscape. Ragweed pollens slough off throughout the year causing different levels of symptoms in people. Known for its contribution to hay fever, or allergic rhinitis, one in five people experience the associated congestion, sinus pain, sneezing and other symptoms that mirror a cold, according to the Mayo Clinic. Speak with a health professional to manage personal symptoms. Herbicide use will help curtail your discomfort by removing the cause. Additionally, if you have exhibited an allergic response to ragweed, contact a licensed professional for application of herbicides to avoid further exposure to allergens.
The application of a single herbicide is not always effective. If the ragweed in your landscape is infested with stem-boring insects, the damage they cause often inhibits the ragweed plant's normal functions. The herbicide is not taken up and transferred to different parts of the plant, deeming it only minimally effective. Chemical resistance occurs in ragweed as well. Repeated applications of a particular herbicide causes ragweed to build up an immunity to the chemical. Resistance does not completely rule out any efficacy of the herbicide, but control is not substantial enough to remove the ragweed.
An herbicide program is an essential component of ragweed control since a single application is not enough. Your best option is manually controlling weeds through tillage and the application of a preemergence herbicide. Preemergence herbicides are chemicals applied before the weed sprouts and develops. Use an herbicide with the active ingredient atrazine. Follow up with a postemergence herbicide with the active ingredient glyphosate once ragweed begins to develop but before it reaches a height of 4 feet, for most effective control, according to the Purdue Extension. As each crop, region and previous treatment history create different circumstances, contact a licensed professional or your local county extension agent for an herbicide program tailored to your home gardening space.