Lettuce Thinning Goes Automated with New Machines

Lettuce Thinning Goes Automated with New Machines

As the winter lettuce production capital of the country, Yuma, AZ is a hotbed of activity in the fall, winter, and early spring. The University of Arizona’s Yuma Center of Excellence in Desert Agriculture (YCEDA) joined the fray this fall by hosting a unique event highlighting some of the technology aimed at solving challenges in the lettuce and specialty crop industries. Among the most popular equipment discussed at the Automated Thinning and Weeding Technologies Field Day was automated lettuce thinners.

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Lettuce is unique in that it is usually planted at very high populations, often up to five times higher than the desired stand. In the past this may have been due in part to poor germination and stands, but with recent developments in genetics and seed treatments this has become less of an issue. Today, the tradition continues because lettuce is a very valuable commodity and often pre-sold to distributors, so growers can’t risk not meeting production goals.

With lettuce being planted at such populations and most fields experiencing good germination and emergence, the result is extra plants that must be removed from the field to ensure the desired plants have access to the space, sunlight, water, and the nutrients they need to successfully grow. This means that farms must hire large numbers of seasonal workers to manually thin plants, trusting that they will select the most vigorous plants, use consistent plant spacing, and thin to the correct population. But, because they’re human, this method is far from perfect.

Hiring seasonal workers is also expensive and will only keep becoming a larger expense for farms as wages rise. In California, where a majority of lettuce is grown, minimum wage will be $11 per hour starting January 1, 2019 and will rise $1 per hour each year until 2023, topping out at $15 per hour. In 2023, a crew of 15 lettuce thinners could cost upwards of $1,800 per day, and it would not be surprising if this number continues to grow.

Aside from labor costs, worker shortage is also an issue, made more serious by the United States’ current stance on immigration. Laborers still in the industry are often older, with their children now living the American Dream from increased access to education and better jobs. Many of this rising generation are not interested in agriculture and the often back-breaking effort of fieldwork.

With these serious concerns around labor, it’s no surprise that many growers are turning to technology to automate processes on the farm. Automated lettuce thinners are one such technology, with many systems in the market or in development for a decade or more. According to research from the University of California, lettuce thinners can cut labor costs by about 61%, can cover more acres per day, and will maintain or exceed the quality of thinning compared to doing the work by hand.

At the Automated Thinning and Weeding Technologies Field Day, growers and other industry members had the opportunity to learn from companies developing machines and watch them operate in the field. Three lettuce thinners were on display from Agmechtronix, Mantis Ag Technology, and Vision Robotics, Corp. All three machines use the same principles – cameras to detect plants, advanced computers and artificial intelligence systems to process information, and a spray application system to deliver a dose of fertilizer or herbicide to remove unwanted plants.

Watching the machines run in the field, it became clear just how much more efficient these systems can be. One individual drives the tractor while another follows behind and ensures that the machine is working properly, making recommendations to fine-tune the timing of spray application. The tractors moved at a steady speed of between 2.5-3 mph, much faster than the often 1 mph or less of hand-thinning crews. The systems effortlessly thinned lettuce in both clean and weed-infested fields that were planted for the YCEDA field day demonstrations.

All three machines were able to achieve similar results, a testament to the work that has been put in by these companies to engineer and develop high-performing lettuce thinners. The choice between the machines comes down to grower preference, customizability for their specific growing conditions and row configurations, and availability of supporting organizations or personnel.

When it comes to hurdles that growers may face when considering automated lettuce thinners on the farm, the biggest, not surprisingly, is price. These are sophisticated machines with a substantial amount of technology. Depending on configuration, prices can range from $250,000 to $400,000. However, when looking at labor costs of hand-thinning spread out over hundreds or thousands of acres, these machines could easily pay for themselves over the course of one or two seasons.

Overall, automated lettuce thinners will solve some of the biggest challenges that specialty producers face – labor availability, labor cost, and quality of work.