On The Shelf
By: Ted W. Mills, ARS Consulting Rosarian and Judge
Have you ever applied a trusted chemical to your roses and experienced no results in coping with blackspot? Do insects keep damaging your prized rose bushes even if you have just sprayed with a reliable chemical? If the answer to these two questions is in the affirmative, you may be a victim of expired shelf life in chemicals. Spray products that have lost their "punch" just may have rested on the merchant's shelf or your shelf too long. It is a problem that affects almost everyone who grows roses. Let's talk about it.
A rose society president contacted me about this "shelf-life" problem. He stated that many rosarians in his group are in a quandary when it comes to determining the length of time that various chemicals remain effective. He asked that I write an article addressing the problem. As I thought about this subject, it is almost like asking the question, "how high is up?" Realistically, there are too many variables to make a declaration that fits all circumstances. Let's review a few and perhaps the rosarian can prevent some deterrents to retaining chemical effectiveness.
Oh, I realize that chemical companies declare that their products have an established shelf life from two to seven years. However, I am not so naive as to take that statement at face value. Providing product longevity requires diligent care on the part of the manufacturer, the shipper, the merchant, and the rosarian.
The initial action on reviewing all pesticides is strict adherence to manufacturer's labeling instructions. Some may not think this to be important and simply rely on their own judgment. However, no one knows the chemical as does those who produce it. If the label states one tablespoon -- that's what it means. Don't ever overdose; however, under very hot weather conditions, some rosarians reduce the dosage and this is permissible.
Monitoring shelf life of pesticides does not begin with the date of purchase. The date of compounding is the accurate start. That is one reason "fresh" chemicals should always be bought at the point of sale. Recording the date of purchase on the package helps to keep track. Try to buy products from merchants who experience a fast turnover in sales. Products setting on store shelves soon expire as the time clock is always running.
One mistake made by rosarians is the purchasing of large quantities of pesticides that are carried over from one growing season to another. It is an ideal policy to buy only the amount that will suffice the current year. Manufacturers can help in this situation by packaging smaller quantities. If chemicals are carried over from one season to another, be sure and store these in secure containers that are devoid of heat or cold. Freezing temperatures, as well as very hot conditions, have a tendency to break down chemicals and render them useless. Exposure to bright sunlight in clear bottles will also damage the contents. Storage in an opaque container that is insulated and locked is a good policy. It will not only slow down deterioration of product but will ensure that children cannot tamper with the contents.
One thing that is very important pertains to regularly inspecting your stored chemicals. Watch for indications that the product is ready for disposal. If severe clumping or difficulty in mixing is occurring in soluble powders, an expiration of effectiveness may be prevalent. If adding water to an emulsified concoction does not produce a milky solution, it may be a signal of ineffectiveness.
Speaking of disposal of expired chemicals, it is important that these be disposed of according to legal disposal methods. Some communities have a regularly scheduled pickup for expired hazardous chemicals and everyone should abide by this mandated requirement.
One thing that could enhance the use of effective chemicals is a requirement of manufacturers to place expiration dates on chemicals, provided these are used and stored properly. As we all know, medications carry expiration dates and so should pesticides. This is something that EPA should investigate and ratify.
Finally, the proper establishment of shelf life information for pesticides is a variable task. It requires care on the part of all those involved in the production, shipment, storage, and use of these chemicals. Rosarians need to rally to this important endeavor. If I leave nothing with you other than a reminder to always follow labeling instructions when dealing with pesticides, I have accomplished much in his treatise. Careful caution is the call.