What Is Systemic Herbicide and How Does it Work?
Systemic herbicides are a type of post-emergent weed killer that absorbs into the system of the plant to kill the entire thing completely from the leaf to the root. Systemic herbicides work slowly, as the plant takes more time to absorb and process the poison.
They are mostly used against annual weeds to kill off the roots, but they can be just as effective against perennial weeds. They contain a number of active ingredients that work to penetrate into the roots of the plant to kill them. Most forms of systemic herbicide are sold in powder or granular form, and need to be activated with water.
Systemic vs. Contact Herbicide
When it comes to herbicide, there are two kinds: systemic and contact. As mentioned, systemic herbicides work by gradually killing the plant from the inside out. Contact herbicide will kill the plant immediately, but isolate its target to kill only the portion that it has contact with.
There are benefits to using both types. Systemic tends to be a more thorough and complete weed killer, as it works through the whole plant, not just from the outside. It is also able to kill larger weeds, which often re-sprout from the roots that remained from the previous killing. Systemic herbicide is also preferred when tackling perennial weeds, which tends to come back repeatedly over a period of time.
Systemic herbicides do have their drawbacks. Because it takes some time for it to work, it leaves a small window for new weeds to grow in that time. There can also be a drift during application that could spread the herbicide to other desirable plants that you didn't intend to kill. In addition, systemic herbicides can only be applied within a narrow temperature range, which is around 65°-80° Fahrenheit.
Contact herbicide has a more immediate effect on killing plants, and can help get rid of weeds nearly instantly. This provides a great short-term solution for clearing a few random weeds before a house gathering or while trying to sell your home. However, because of its rapid results, it doesn't necessary kill the roots of plants, which could remain and cause re-growth later on.
Should I Use Systemic Herbicide?
Systemic herbicides are generally meant to be used against hard-to-remove annual weeds. These may include: annual mercury, black bindweed, field forget-me-not, Fool's parsley, wild radish, lesser trefoil, and others. Because they are so thorough, they should be applied to plants that will feel their full impact.
It can also be used again perennial weeds, but only if they have been found to be particularly difficult and resistant to contact herbicides.
There are several ways to apply systemic herbicide to plants. Although the most common forms are sold in powders or granules, they can also be liquid-based and applied into the soil. Active ingredients in systemic herbicide are dinitroaniline, bipyridylium, and substituted urea.
Systemic herbicides can help get rid of stubborn weeds from your lawn almost permanently, especially when applied correctly. As with any form of chemical, read the label carefully and follow the instructions that have been outlined for the proper usage.