Shelf Life of Stored Agricultural
Chemicals
pdf
Anyone who has ever used pesticides probably has
a partially filled container that they carry over from one year to the next.
The question then arises as to how long stored agricultural chemicals
retain their effectiveness. Unfortunately
there is not a lot of solid information about shelf life of most materials. The
links at the bottom of the page will take you to tables listing the shelf life
of a few materials.
However there are a some general
principles that you might find useful in maintaining your agricultural
chemical storage area:
- Water
based materials are usually damaged by freezing. Also, freezing may cause the container to burst.
Freezing is usually not a problem in our climate but it can happen in the
winter, the time of the year when one is least likely to be thinking about
the pesticides. Some
materials will begain to separate at temperatures below 40o F
- High
temperatures will decrease the shelf life of many materials.
Two examples are: Malathion WP, and Thiram WP. There is probably
not much that can be done short of air conditioning to keep a storage area
at the ideal temperature, however keeping susceptible materials away from
walls may help.
- High
humidity may degrade some of the wettable powders.
Keeping the containers tightly closed will help. (For safety
reasons all pesticide containers should be kept tightly closed.)
- Plastic
containers tend to get brittle with age and can start to leak after they
are 3 or 4 years old or if dropping or rough handling has dented them.
- Labels
can be damaged or fall off. If
a container loses its label and the contents cannot be positively
identified the material becomes toxic waste, which can be expensive and
difficult to get rid of.
If a material has been stored for more than 2 years or
has been subjected to unfavorable conditions such as freezing, be sure to
check it before you plan to use it if you are not familiar with it, as it may
have become unusable.. Some of
the things to look for are:
- Wettable
powders are lumpy, or the powder will not mix with water.
- Dusts
and granules are excessively lumpy. This will affect calibration and may
also indicate that the material has lost effectiveness.
- Emulsified
materials have settled out or become lumpy.
- Emulsifiable
concentrates do not produce a milky emulsion when mixed with water, or
some of the material has separated.
- Oil
sprays; the solution has separated or has formed a sludge.
The links below will take you to tables listing the shelf life of some materials.
http://n-fl-bugs.ifas.ufl.edu/more/Guillebeau.htm
http://ohioline.osu.edu/b745/b745_11.html
http://entweb.clemson.edu/pesticid/saftyed/storage.htm#web%20sites
http://pmep.cce.cornell.edu/facts-slides-self/facts/gen-peapp-shelf-life.html