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Why do we plant blue and green corn seeds?

Refuge In Bag explained from a sorter technology manufacturer.

The blue color comes from the seed treatment used to protect seed from diseases allowing enough time to protect the seed to germinate.  Different treatment companies use individual colors such as pink, red, and orange to name a few.  In this example we will use green and purple colors.


There are two colors of seeds, a green/blue corn seed and a purple/blue corn seed, in the picture on the left. You can clearly see that there are more green/blue seeds which make up the majority in the bag with the remaining purple/blue corn seeds referred to as “refuge seeds”. The two colors simply differentiate between a treated seed and a refuge seed in each bag. Hence the term, REFUGE IN BAG or RIB.

In this seed color example, the green/blue corn seed has been resistant treated. There are many plant diseases found in soil and so the treated corn protects itself from certain insects. The corn is basically bred to defend itself without using pesticides and insecticides. For your reference, treated corn is considered GMO and is a Genetically Modified Organism and allows the treated corn seeds to protect crops from insects such as rootworms and many others.

So, why refuge seeds? Refuge Seeds or untreated seeds, which again are the purple/blue corn seeds in the picture, are added to the bag to help fight off insect resistance for the treated seeds. These purple/blue refuge seeds are not resistant (not treated) and this makes sure that some of the next generations of insects are not resistant to future seed treatments. In other words, some insects will be resistant to the treatment and as they reproduce with non-resistant insects then the offspring of that generation are vulnerable to future treatments. If we didn’t plant refuge seeds along with the treated seed, there would be a fast increase and large number of insects that are resistant to treatment. There is a need to blend seeds for both resistant treated and refuge seeds, but there is a bigger need to measure that blend. VMek Sorting Technology is the industry leader and has developed unique seed-based sorting technology for the agriculture seed industry for Refuge In Bag and other sorting requirements.


  “Seeking to increase productivity and lowering labor costs for agricultural seed services including counting, sorting, weighing, and reporting for Refuge In A Bag (RIB), Count Per Pound (CPP) and Thousand Seed Weight (TSW) were initially the reasons for consulting with VMek Sorting Technology” said Sarah Graybill, Seed Lab Manager at SGS, Inc. “Implementing VMek Sorting Technology solutions was a very easy decision for our company. The Metrix Analytical Color Sorter is fast, accurate and reliable providing consistent results of less than 1% detection errors which are then verified using instant analytical reporting features”.

VMek Sorting Technology has partnered with world leading companies in the agriculture seed industry helping lab managers sort, analyze, count, and weigh all types of agricultural seeds. The Metrix Lab Analytical Color Sorter technology advances seed applications such as Count Per Pound (CPP), Refuge In Bag (RIB), Thousand Seed Weight (TSW) using real time individual seed and lot data analytics. They are also used in Quality Assurance, Seed Certification and Production Testing across all seed platforms in all types of agricultural seed applications.

Thomas Mann
Sales Coordinator
VMek Sorting Technology