Misconceptions, Questions, And Answers On GMOs

Misconceptions, Questions, And Answers On GMOs

If you’re not a scientist or you are new to the subject of GMOs you might be wondering: Where do I even begin with what to ask about GMOs and vegetables?


Just “Google” GMO crops and you’ll get a mix of websites. Some offer informative, possibly objective, answers to the search query as well as anti-GMO websites where you can almost hear and feel the emotional uproar jump up at you from the computer screen. Emotions aside, truth must be achieved, not perceived, and one way to do that is by asking the right questions.

Three GMO vegetables are currently available in the U.S. market: sweet corn, summer squash, and potato. Industry experts were asked to provide feedback on these crops, including common questions and misconceptions they receive about GMOs within their areas of expertise.

SWEET CORN: Dr. Galen Dively, University of Maryland Professor Emeritus and IPM Consultant 

For sweet corn, the question is in regard to Bactillus thuringiensis (Bt) sweet corn. Most growers ask about herbicide tolerance, says Dr. Galen Dively, Professor Emeritus at University of Maryland and IPM Consultant.

“They want to know about the herbicide traits – which ones – and if there’s one or two in the seed,” he says.

The answer, of course, will depend on the brand of sweet corn growers select to plant. For example, the Attribute II trait stack by Syngenta has tolerance to Liberty (Bayer CropScience) herbicide while Monsanto’s Performance Series sweet corn contains Roundup Ready technology. “A lot of growers like the herbicide traits,” Dively notes.

The second question he gets asked frequently is if growers have to spray  — at all — for insects when using this type of sweet corn. The driving pests that dictate control in the Northern and mid-Atlantic production areas are the lepidopterans, such as the European corn borer.

“In most cases, sweet corn with the Attribute II trait stack from Syngenta does not need insecticide treatment at all because the Vip3A protein is highly effective,” Dively says.

He also gets asked about secondary pest pressure. Even though Bt sweet corn is used to manage major pests such as lepidopterans, growers may still need to spray for sap beetle and stink bug depending on the pressure, he says. Insect pressure indicates how severe populations are in a field, which can only be measured through monitoring.

In south Florida, silk fly is approaching major pest status. “If they use Bt corn to knock out fall armyworm down South they still have to deal with silk fly,” he adds.

Dively also says he receives questions from GMO growers about how to deal with customers’ questions, for example at a retail farm market.

“I agreed to go to one grower’s produce stand on weekends to talk to customers to explain the technology,” he says. “Most people don’t really understand how safe the Bt protein is; it’s more of the method of genetic insertion that they’re against. Also, the Bt protein in the corn is the same protein sprayed on organic sweet corn, which can be sprayed on the crop even on the day of harvest.”

SQUASH: Dr. Bill Johnson, Squash Breeder, Seminis/Monsanto Vegetable Seeds, Monsanto Company

Dr. Bill Johnson, Squash Breeder with Seminis/Monsanto, breeds GMO squash as well as non-transgenic squash for regions that do not accept GMOs for customers who do not want or need transgenics.

According to Johnson, there are only two transgenes approved for sale/consumption in the U.S. He only uses the one that was released last because it provides resistance to three viruses (cucumber mosaic virus, zucchini yellow mosaic virus, and watermelon mosaic virus) instead of the transgene released first, which provided resistance to only two viruses.

“We [breeders] actually work with just one transgene, but we can backcross that transgene [through traditional breeding methods] into many different genotypes, varieties, and/or market classes,” he says.

This allows for continued success for GMO squash production. Johnson still uses non-transgenic sources of resistance for these three specific viruses, which are not as effective at mitigating disease symptoms, but are unregulated.

Because the cost of research required to achieve de-regulation of a transgene is currently more than $100 million, according to Johnson, then the total squash seed market, and actually most vegetable seed markets with the exception of potatoes, is not large enough to merit the investment of developing new transgenes.

“I can now demonstrate very strong progress in improving the marketable yield of squash that include the transgene,” Johnson says. “Simultaneously, our progress for improving yield in non-transgenic hybrids has been steady, but not as rapid.”

When asked about the kinds of questions he gets from consumers, Johnson responded, “It’s a funny thing that I actually don’t get nearly as many questions about it as you would expect. Considering how much publicity there is on the subject of GMOs, not much gets through to me.”

He further added: “A lot of the bigger commercial squash growers have direct access to an industry sales rep who can answer their questions,” he says. “There are a lot of layers between me and the growers.”

And, if Johnson happens to get asked something by someone who is not familiar with what he does then he said he ends up answering mostly basic biology questions

POTATOES: Dr. Walter De Jong, Associate Professor at Cornell University

One of the more recent vegetable GMOs on the market is the Innate potato produced by Simplot. Similar to Johnson’s experience, Dr. Walter De Jong says that “so many people just don’t even know what questions to ask – they don’t understand the biology of GMOs. However, a more common strand is the distrust of large companies tied up in GMOs.”

De Jong has an Extension appointment at Cornell, so he interacts with the public and with growers. “When it comes to the public, there’s very little specificity when someone asks me questions, and growers are not asking me for help on responding to consumer questions. I talked about Innate at meetings to let them know it was coming.”

DeJong notes that the name of the new potato reflects the fact that potato DNA is simply being put back into potato. This engineering technique, called Ribonucleic Acid interference (RNAi), allows the silencing of four genes in the tubers to create fewer bruise symptoms (i.e. brown rot), prevent potatoes from turning brown when cut, and reduce an amino acid called asparagine. Reducing asparagine will decrease acrylamide levels, a naturally occurring chemical in most starchy foods when cooked that some suspect of being carcinogenic.

DeJong also points out that as a result of ‘Innate’ not having the traditional GMO traits, e.g. no antibiotic gene, no herbicide gene and no Bt, then it will be a curveball for the environmental movement because the usual talking points will be lacking.

“How will the public react?” DeJong wonders. “I don’t know. My own view is that this is a big trial balloon in the sense that if there’s not much commotion then I think all vegetables are up for modification.”

Since the technology is new in a food commodity, some comments that may be raised, DeJong says, will be whether or not RNAi is safe.

“To Simplot’s credit, they have been very transparent in the process,” he says.

Globally, the most recent advancement in vegetable GMO’s is with Bt eggplant.

After years of rigorous governmental review, ‘Bt Brinjal’ (eggplant), developed by Maharashtra Hybrid Seeds Company in Bangladesh, was commercialized for production in 2013.

Whether the number of GMO vegetable crops will increase in the near future could depend on several factors. The stakes are high. The entire process from development to regulatory approval of a new GMO costs companies well over $100 million, which is a large risk for creating a cost-effective return on a company’s investment in GMOs.

For example, more than 20 years ago, a GMO tomato was withdrawn from commercialization due to economic instability. Besides prohibitive costs, there are obvious social and environmental influences on the current and future development of vegetable GMOs.

Will the pressure for increased sustainable pesticide usage and the need for growers to feed more people on shrinking productive acreage create a situation where the use of vegetable GMOs will become the rule as opposed to the exception?

The clock is ticking, and only time – and pressure – will tell.

Dr. Brill is a freelance writer based in Pennsylvania.