Agri-Fos is phosphate compound formulated to stimulate growth in trees.    Research has shown that about 80 % of trees respond well to treatment, meaning that their defenses are stronger.

Applications should be made when the tree is actively transpiring.  Avoid treating trees during very hot or very cold weather.  Also, avoid applying the compound when deciduous oaks have lost their leaves or when new leaves are emerging in the spring.

Currently in Northern California two applications in the first year are recommended, one Fall treatment in late October through early December or a Spring treatment, March through May, and a second treatment approximately six months later.  Subsequent treatments should be made once every 12 to 24 months.   Expert opinions on how often to spray are evolving.  Please check additional resources for the most current recommendations.

 

Preventative treatment, before infection has occurred, has been found to be more effective than curative treatments.  At least 4 weeks are necessary for the applied chemical to take full effect. 

 

Agri-Fos should be mixed per the manufacturer’s directions.   Spraying should be consistent with these spraying guidelines .

Many homeowners elect to do this work themselves.  Caution:   Agri-Fos is relatively benign, but the Pentra-Bark compound it is typically mixed with can irritate the lungs and the skin as well as cause nausea and head aches.     Avoid "over spray" and heed the manufacturers instructions on wearing protective equipment. 

For the non-do-it-yourselfer, we've heard recommendations for the following spraying contractors .