Trees absorb water and other compounds present in the water such as herbicides and trace minerals. The Xylem then transports water throughout the tree by use of the water gradient. Water moves from areas of excess water (roots) to areas of less water (trunk and branches) via the xylem. Roots normally absorb and retain large amounts of water and this water moves from the roots to the stem and then to the leaves. This method of transport does not require living cells or living processes and occurs independently. The phloem generally moves sap from the leaves to the roots and requires living cells and processes to mediate this transport. Living cells are also required for cell to cell transport.
Many methods have been used in the past to kill tree roots and remove them from a sewer line using chemical rather than mechanical methods. These have included—                1. The use of hot water which uses heat to kill the roots. This requires the heating of water to near boiling point and then soaking the line with it. The disadvantages are the great cost of heating the water and the problems of taking a sewer line out of service during the treatment period.        2. The application of inorganic salts, most notably Copper Sulfate. Although copper sulfate is still used in some households, its use has been banned in many states due to toxicity problems with copper in treatment plants (it kills the necessary treatment bacteria) and discharge into rivers and streams resulting in toxic loads which kill fish and other aquatic organisms. Other inorganic salts and corrosive acids and bases which are less toxic to the environment are not supported for registration with EPA and may not therefore be used in this type of application.        3. Dichlobenil has been used successfully for many years in sewer line root control. Support for its registration has been suspended in some areas by its manufacturer (due to testing expenses). It kills roots on contact in low doses and prevents root re-growth for several months as long as it is not washed away. It does not kill the roots more than 1-2″ back from the contact site which limits its effect.        4. Metham Sodium has been used for decades in sewer line root control and as a fungicide fumigant. It yields a poisonous and caustic gas which kills roots very effectively (100%) inside the pipe and outside the pipe where the gas travels. Its disadvantages are its effects on humans (it causes burns similar to that of mustard gas) and its effect on non-target vegetation and surrounding environment. It kills treatment plant bacteria, fish and other aquatic organisms in tiny doses. The environmental effects are usually small but have been disastrous in highly publicized circumstances such as tanker car leaks.        5. Diquat came into sewer line use in 1999. It is very environmentally friendly and generally kills roots on contact. It has had mixed results in the industry, being rejected after testing by large municipalities for inconsistent results. This is due to the fact that Diquat is rapidly inactivated by organic materials in soils and detritus on roots. Roots are often coated with debris which consists largely of fatty acids, waste products, tissue paper, etc. which absorbs the Diquat and binds it in a form which makes it inactive. This results in treatments in which clean roots are killed and coated roots are generally unaffected. Since roots filter the flow of water through them in the sewer lines, they very often have a significant buildup of organic detritus which prevents the Diquat from reaching it intact. This results in spotty and inconsistent root kill.        6. It is also known that salts of sulfamic acid such as ammonium, magnesium, potassium and sodium sulfamate also have root killing properties. The ammonium salt form is systemic and can kill the entire tree in sufficient amounts and because of this has not been used commercially in this application. The use of the sodium sulfamate salt in the commercial application of “Root-X with Dichlobenil” has been used with modest success since 1990.        
Some of the above chemicals may be delivered into the sewer lines and onto the tree roots to be effective. Some methods include—                A. Delivering the herbicide with the flow of water and hoping that the chemical is captured and/or absorbed onto the roots in necessary quantities to kill them. Some of the chemicals are produced in the form of a solid cube (copper sulfate) which ideally becomes entangled in roots partially retarding the flow in the bottom of the sewer line. These roots absorb the copper and die.        B. Spraying on the pipe surfaces and roots with a water carrier. The herbicide is washed away with the water flow leaving almost no amount to be absorbed onto the roots. Some of the water herbicide mix is expected to displace water present in the root mass and detritus and thereby effect some root kill. Soaking of the sewer lines for at least an hour has yielded good results commercially with this method.        C. The use of foam which slows and further reduces the drainage of water and herbicide. This has been accomplished by using air compressors to generate the gas and surfactants to generate the foam. Foam has also been achieved using chemicals which release reaction compounds when brought together in water (CO2 from sodium bicarbonate and acid) with surfactants. When the foam is chemical and used as gravity flow delivery it travels down the pipe until it collides with roots hanging down and becomes obstructed or diminished and does not get on further root intrusions at joints downstream unless that are hanging down in the water flow. This has been a significant disadvantage when using a single pour in application method.        D. The application into the line as a gas (Metham Sodium gas, Dichlobenil known as Vapo Rooter). This method is effective but is environmentally undesirable and hazardous to humans who come into contact with it.        E. The application into the line as a dry dust blown in using air pressure. This method, while effective would blow the dust out of vents above houses and into homes with dry traps creating undesirable effects and has not been adopted commercially.        
These various techniques have an array of drawbacks. Accordingly, there is a need for a foaming root killer composition drastically reduce the environmental load of herbicide, prevents root re-growth in sewer lines long term and saves homeowners and municipalities money on repeat applications and pipe replacement.