b'Skin set is also important, but difficult to manage in wet or dry conditions. At harvest, equipment needs to be well maintained and operated correct-ly. Conveyors should be filled to capacity to keep potatoes from striking chain links, and ensure the harvester is operating at full capacity. If the conveyor is under-loaded, slow its speed to synchronize it with the other conveyors. Minimize movement and drop heights, and cushion impact points. Train staff on the importance of minimizing bruise through careful handling. DETECTION DEVICETo mitigate bruise, one must first know where bruise occurs, says Patrick Morris, sales and marketing director at Techmark Inc. Techmark offers a solution for detecting problematic transition points in the handling system. The companys Impact Recording Device (IRD) is a small, globe-Pressure shaped device that goes through the handling system exactly as a potato would.bruised tuber. Inside, an accelerometer measures impact force and duration.PHOTO: PAT DOLNot all impact is created equal, explains Morris, as different surfaces absorb different amounts of energy. Its not just the impact that your crop experiences, its how it experiences it and over what time, he explains. Once the device has gone through the system, the data is presented in the form of a graph that shows a visual representation of the impact points along the handling system. Growers can set thresholds. Thresholds are based on research Black spot that shows what a potato can take before it expresses bruise.bruising can occurAll points above the threshold are points of impact that have the potential towhen handling potatoes cause bruising in the final product, says Morris. Points below the threshold linewith low nutrition and weak cell walls. are points the producer doesnt need to focus in on.PHOTO: EMMERSON For best results, Morris suggests that producers run the IRD through theMCMILLANsystem several times.The IRD helped uncover problems for one grower in Michigan who was getting high levels of bruise in a newer field with a lot of rocks. He knew rocks were causing the bruise, but he didnt know where it was occurring during transfer. In this case, the IRD revealed that the drops on the conveyor were too high. But the problem wasnt just potatoes dropping on potatoes. Rocks were dropping on them as well, and the damage incurred was setting them up for challenges in storage. The information collected by the IRD was used not only to make changes in the transfer system, but also to support managers in their training of workers.Youre never going to get rid of 100 per cent of touches on your potato because you have to handle them, says Morris. Youre trying to get rid of the worst of them to bring your bruise percentage down so that with the final product, the chip expresses less bruising in it.Pressure bruise in storage is also a big issue for growers. Bruised pota-toes become a gateway for pathogens and other storage issues. The key to good storage is high humidity and careful temperature man-agement, says VanderZaag. Temperature spread between intake air and the temperature of the pile has to be as narrow as possible. In conditions where intake fresh temperatures are much lower than the pile, moisture will get sucked out of the potato, as colder air holds less moisture. FALL 2019 SPUDSMART.COM 19'