Nothing spells the death of a subsurface drip irrigation (SDI) system taster than root intrusion. With more growers placing drip irrigation lines below the soil surface, the need for a better understanding of how to keep roots out of drip emitters has also become more important. Work done at The ('enter for Irrigation Technology (GIT) over the past 10 years has given us some insight into how to protect emitters from root intrusion.
Chemical barriers have been shown to be an effective method for preventing roots from entering the discharge point of the emitter and traveling up into the tube. The herbicide Treflan or Trifluralin (a similar formulation) is commonly used (where legal) to provide the chemical barrier. These chemicals stop ceil growth at the root tip as it comes in contact with the chemical. The root tip will appear blunt and stubby, with no sign of root hairs.*
Well-watered plants will not typically CM use problems with root intrusion. However, sudden weather changes, such as a rise in temperature, or deficit irrigation practices will encourage roots to seek water remaining in emitters. Without some type of protection or harrier, the emission pathway will eventually become plumed with roots.
There are two basic approaches to providing a chemical barrier to the emitter. The first is to inject a registered herbicide on a periodic basis, taking care to follow label instructions on amounts and timing. Generally, you will want to apply these products in relatively drv soil, as a saturated environment may move the herbicide beyond the immediate vicinitv of the emitter. The herbicide should be injected over a short period of time, followed by a system shut-down to allow time for the material to become bonded to the soil particles. The frequency of application will depend on label instructions, annual water applied, soil type, irrigation strategies, etc..