From the GPC site: “The Great Pumpkin Commonwealth’s (GPC) mission cultivates the hobby of growing giant pumpkins throughout the world by establishing standards and regulations that ensure quality of fruit, fairness of competition, recognition of achievement, fellowship and education for all participating growers and weigh-off sites.”
Meer info: https://gpc1.org
Some growers of Pompoenengenootschap Kasterlee are GPC member.
Next to that, since 2019 the Pompoenengenootschap Kasterlee organizes the Belgian GPC weigh-off. More info about the weigh-off: Belgian GPC weigh-off