With the myriad of sometimes conflicting regulations on
soil fumigation, it’s a good idea to check with the county
agricultural commissioner to confirm what compounds
are available in a specific area during the planned
Soil fumigation is often a major investment when replanting an almond orchard. It is important to first identify whether fumigation is necessary by assessing soil samples and orchard history. Based on that assessment, a grower or PCA can determine whether to fumigate and which compound(s) work best for the specific situation.
In many cases, soil fumigation is the only truly effective method for addressing aggressive pathogens and nematodes in the orchard. Decisions, however, don’t stop at that determination. They are further complicated by the many regulatory hurdles related to soil fumigation. For that reason, we recommend that once you have decided to fumigate prior to replanting, your first step should be to meet with your county agricultural commissioner’s office to find out what compounds are available for your county, site and timing due to regulatory restrictions.
In the end, regulatory issues may play an even larger part in the grower’s fumigant decisions. There are several major regulatory issues that are impacting the grower’s choice or combination of soil fumigant materials at the international, federal and state levels.
In compliance with the Montreal Protocol, methyl bromide has been phased out for use as a soil fumigant, except under highly specific critical-use exemptions (CUE). The amount of methyl bromide available for tree replant under the CUE goes down each year, and it has become very expensive.
As of January 2011, there are new federal label requirements for methyl bromide, chloropicrin and metam sodium that include the development of a fumigant management plan, new safeguards for worker and applicator protection, and new staffing requirements.
In the San Joaquin Valley, air quality rules enacted in 2009 have imposed severe limitations on the rate, timing and application method of common fumigants during the ozone period from May 1 through Oct. 30.
And the use of Telone continues to be limited by township caps.
Given these complex and sometimes contradictory decision points, your local ag commissioner is a good place to start to help sort out what restrictions exist and which compounds are available to you in your area at the time you plan to apply.
This article, by the Almond Board’s Gabriele Ludwig and Bob Curtis, is a summary of the third and last in a series of articles on orchard replanting in Western Farm Press. The complete article is in the May 21 issue, page 20, and all three articles in this series are online at westernfarmpress.com/tree-nuts.