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Robot Grafting

y using robot technology, we can eliminate the need for a lot of hand labor,” Dr. Richard Hassell says as he shares with me the story of a technology he developed; taking a big idea and turning it into a strong, concise summary.

Robotic hands are unfolding as technology’s grip on produce becomes ever-more efficient. Now, a process that has helped to build stronger plants and deliver more durable produce is taking a bite out of that cutting-edge. This new technology, developed by Dr. Hassell, Clemson Cooperative Extension’s South Carolina’s State Vegetable Specialist, is the robotic method of plant grafting.

Dr. Richard Hassel, Clemson Cooperative Extension’s South Carolina’s State Vegetable Specialist“We’ve been looking at grafting now for about five or six years,” Dr. Hassell explains. “Overseas they have such limited ground that they’ve always had problems with soil-born diseases, so they have been grafting for years. The whole idea of grafting is to combat soil-born diseases by using two types of rootstock.”

Here in the U.S., the grafting method is still relatively new in our industry, and Dr. Hassell has a very good explanation as to why.

“In the United States, we’ve always had the opportunity of rotating land, plus the use of soil fumigation. But both of those are now becoming a major concern to our growers because they are running out of land to rotate. So, they are running into soil-born diseases because they can’t fumigate their ground,” he shares.

But plant grafting is both labor-intensive and time-consuming, translating to a high expense for U.S. growers. Dr. Hassell and his team set out to change that as our resources shift.

“The whole objective of our grafting procedure was to reduce the cost in the United States. Grafting is normally done all by hand, and it can be very expensive. So one of the aspects we were looking at was how to reduce cost for our growers overall,” Dr. Hassell elaborates.

And that is what the team achieved. Quicker, consistent, and automated, this plant grafting robot offers a cost-saving solution for growers looking to naturally strengthen categories susceptible to soil-born diseases.

To give you some idea of how many categories in the produce industry could be affected by such technology, some of the plants grafting is used on include key categories like watermelons, cantaloupes, tomatoes, and peppers; all susceptible to their roots collapsing as they work to grow in the soil.

So, what does the robot do to help? Well, in just seconds, the metal “hand” grasps, slices, and pushes together the rootstock of the fruit and a gourd, grafting a hardier, resistant rootstock.

Once the robot has done its work, the plant is placed in a “high-humidity healing chamber.” The environment encourages the graft to heal, sending out new roots to the plant as it mends over one week, strengthens, and is then planted again.

All to make a stronger, better product, as naturally as possible.

“Overseas there are robotic machines to help grafting, but the problem is you have to recalibrate them almost on a daily basis, which takes a lot of time,” Dr. Hassell shares when I ask about the robot’s inception. “The robot itself doesn’t cut off enough of the rootstock each time, so you get a lot of regrowth occurring. We developed a process and patented it here to eliminate that regrowth.”

With a method that Dr. Hassell explains as “blinding” the root, he and his team were able to keep plant roots from growing any further. Then, after getting a hold of a bot to play with, the team was able to make modifications that birthed its now-patented technology.

“This new process we developed helps graft the plants at a very high rate, so we eliminated any regrowth problems they were having with the plant in addition to cutting down labor,” Dr. Hassell shares.

The robot can produce between 300 and 600 plants per hour, depending on the speed setting, with a take rate of about 98 percent. This is a consistency Dr. Hassell says growers are hard-pressed to find in the U.S. because long-term hires for the job can be difficult to keep.

“The initial cost of the robot is about $30,000, but finding and keeping consistent labor to do this job in the United States is nearly impossible,” he elaborates. Dr. Hassell has seen human hands that can keep up with the technology overseas, but the road it takes to get there seems to be both an economic and cultural separation.

“To see laborers keep up with the robot, like some can overseas, it has taken them 20 to 30 years of doing this eight hours a day for a very low minimum wage,” Dr. Hassell shares. “Here in the United States, where minimum wage can range anywhere from $12 to $15 an hour, it’s difficult enough, and an even greater problem is getting them to stay and do so consistently. This is an art that you have to do correctly each time, something a robot can do successfully without error.”

So, while the initial cost for the bot with Dr. Hassell’s technological modifications can cost around $30,000, it is an investment that could see a long-term payoff for some, and short-term for others.

As he tells me about some of the advantages grafting offers, it occurs to me that the technology could offer something to the organic industry as well. Dr. Hassell confirms my hunch enthusiastically.

“The organic industry doesn’t use any fumigation at all, so the grafting procedure is all organic certified,” he says, adding that Mexico and Canada, both with sizeable greenhouse operations, use grafting frequently as well.

When I ask about room for growth with this technology being introduced and spreading, Dr. Hassel is quick to respond.

“We hope!” he says with a laugh. “Currently, there are no watermelon cultivars, for example, that are resistant to soil-born disease, and we don’t see it happening in the next several years. And there are tomato soil-born diseases that they cannot combat by breeding. Grafting has been able to bring back a lot of heirloom tomatoes because they are susceptible to soil-born diseases, exciting many of the organic industry who can now develop and grow those tomatoes through grafting and developing resistant rootstock.”

Still extremely new, Dr. Hassell explains that the technology has only been available for about a year, but has been very well received.

“I have a lot of growers with smaller acreage already using this technology for their own grafting, but the larger they get, the more it makes sense to go with operations that do grafting exclusively,” he shares. “Right now grafted plants are being produced by several large outfits. Currently, there is one out of California and one out of North Carolina.”

So, what is next for the robot doctor? This project in particular was funded the last four years by a federal grant–the specialty crops grant–and the team is reapplying to take its craft to the next step.

“Because we are continuing to develop our own type of technology to make our own rootstock material in the United States, instead of it coming from overseas, we are currently embarking on another grant through the same agency,” he says.

It seems as though a scientist’s work is never done.