Dimethoate is a systemic insecticide and has been available for 
purchase over the counter for several years and I believe it is still 
available at garden centers.

http://www.wrpmc.ucdavis.edu/NewsAlerts/dimethoate.pdf

Alternative chemistries have been shown to be effective tools, but 
the systemic nature of Dimethoate controls against aphid for a longer 
time, reducing the number of applications. The newer chemistry is 
double to triple the cost of Dimethoate. The producer must use 
multiple applications or must add Dimethoate to the mix to achieve 
effective control. This is neither economically or environmentally acceptable.

Jim Young 

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