The principle and use of pencycuron and carbendazim

Pencycuron and carbendazim are the two kinds of fungicide that people often used, but because of their different action principles, the uses are also different.

There are two basic classifications of　fungicides: Contact fungicides and　Systemic fungicides.pencycuron belongs to Contact fungicides, carbendazim belongs to Systemic fungicides.

Contact fungicides: Contacts remain on the outside of the plant and form a protective barrier against diseases that penetrate the leaf blade.

Systemic fungicides: Systemics enter inside the plant and travel throughout the plant"s vascular system. They are both protective and curative before and after the disease has started.

Contacts Fungicides
After application, contact fungicides will remain on the surface of the plant. They do not penetrate enter into the plant as systemic lawn fungicides do. The primary purpose of contact fungicides is to form a protective barrier against diseases that enter through the leaf blade. In most cases, it needs to be applied before the disease begins.
Most Contacts have as short residual and are only effective for three to eight days. After that, it will need to be reapplied. The fungicide needs to remain on the surface of the blade the entire time to be effective. This means it should not be watered in. You will need to turn off your automatic sprinklers to keep from washing it off. If it rains after the application, it may need to be reapplied.
Mowing or heavy foot traffic may remove the product from the grass making it less effective.
Contacts will not have any effect on diseases that enter the grass through the root system. Anything below the surface of the ground is out of the range of contact fungicides. They will not protect any new blades that develop after the contact was applied. It can only protect the grass it touched when it was applied.

Systemic Fungicides
Systemics, on the other hand, will penetrate the grass blade or enter through the roots and work from the inside. They are longer lasting than contacts and will often last from 7 to 25 days or longer. They can be both curative (after the disease starts) and protective (before the disease begins). It often needs to be watered in after application to get the fungicide down to the root zone. Read the label carefully for specific directions on how to do that.
Systemic lawn fungicides will attack lawn fungus from the inside. Any disease that enters from any point on the plant will be subject to the fungicide. This includes any new plant growth that occurred after the fungicide was applied.
Systemics and contacts are often alternated to get the benefits of both types of fungicides.

Thus in the use process, pencycuron often used to do FS and spray for sterilization, carbendazim can be irrigated to root and absorbed by plant for sterilization.

from:Yangzhou pioneer chemical CO., LTD