Check Insecticide Labels Applied for Spider Mite Before Using Soybean for Forage
Eileen Cullen, Extension Entomologist
Some producers may be considering using soybean as a forage crop given drought conditions this year. Although this is not a preferred option and grain harvest is the norm statewide, the question has come up from UW-Extension county agents working with producers over the last couple of weeks in dealing with drought impact.
The question being, is there a spider mite insecticide that does not limit harvesting soybeans as forage?
Insecticides used as miticide in the Midwest for twospotted spider mite in soybean are limited to the two organophosphate active ingredients dimethoate and chlorpyrifos, and the pyrethroid active ingredient bifenthrin.
Remember, there is a difference between the pre-harvest interval (PHI) for grain harvest and specific label use restrictions pertaining to soybean forage fed to animals. To find label information, you need to look at the label use restrictions remarks section under soybean.
Of the insecticide/miticides registered and recommended for spider mite control in the Midwest on soybean, only dimethoate permits forage use with the label stating “Do not feed or graze within 5 days of last application”. There are many generic dimethoate labels, so be sure to read the label for the product applied to a particular field being considered for forage use, but the information should be the same for all dimethoate active ingredient registered by EPA for use on soybean.
Soybean treated with chlorpyrifos or bifenthrin cannot be used for forage. For example, the label for Lorsban (chlorpyrifos) on soybean states “do not graze or feed treated forage to livestock”. Labels for products containing bifenthrin (e.g. Brigade 2EC and generics, or premix insecticides where one of the active ingredients is bifenthrin) state: “Do not graze or harvest treated soybean forage, straw, or hay for livestock feed”. Another premix containing bifenthrin + chlorpyrifos (Tundra Supreme) states: “Do not allow meat or dairy animals to graze in treated areas or otherwise feed treated soybean forage, hay, straw to meat or dairy animals”.
The Crop Data Management Systems (CDMS) Label/MSDS webpage is a good source to look up label information by product brand name: http://www.cdms.net/LabelsMsds/LMDefault.aspx
If you are considering soybean forage use, make sure you are complying with insecticide label law regarding previous spider mite application.