I believe guilds actually aren't that new of a concept. When I grew up in north-eastern Germany, our fruit trees had currants, brambles, parsley, chives and borage planted under them, as well as numerous medicinal plants, herbs and flowers that I couldn't identify as a kid. Not for space reasons either, they were there on purpose. We also had relatively wild beds of rapunzel, salsify and what I think translates as Scorzonera (Schwarzwurzel) in between and under the fruit trees. There was also some weird legume looking vining plant that made an edible tuber. My grandmother grew all sorts of weird medieval food plants under her fruit trees that are not frequently cultivated today.
I also once visited a very old wild orchard outside of Goettingen, Germany that had herbs and flowers freely spreading and reseeding under the fruit trees.
So I think the guild concept was already there a long time ago. I mean, think about those 13th - 18th century orchards in Europe. Of course the fruit cultivars were more hardy than what we grow today, but pests and diseases did exist and people had no access to any form of modern chemicals etc., even deer fencing was much harder than it is today. Planting plants that support those fruit trees to be healthier seems like the logical solution. Considering all the medicinal knowledge that was lost over time, I'm pretty sure that concepts like guild planting were just lost during the industrialization of food production. If you look back at ancient Rome's kitchen & fruit gardens, we have records of even them growing herbs and food crops under their fruit trees. Considering that they were the first civilization (on record) that put a serious effort into fruit tree cultivation and cultivar selection, I would say that guild concepts are probably as old as fruit tree cultivation itself. Records show that romans definitely grew garlic, coriander, chick pea, fennel, flax and all sorts of beans under their fruit trees, and that's just what has been confirmed. Likely, they grew all sorts of old food crops under them like Reichardia picroides and other plants nobody grows for food any more. Some of the roman garden manuals even mention the plant feeding effects of legume family plants. There are also records of many of the above mentioned plants being grown under the olive, date, pine, peach, plum, apricot & almond trees in Egypt around the same time period. So yeah. Can we really say someone invented guilds? They might have been called something different before. But come on people. The idea to grow fruit trees on what is pretty much a grass lawn is a relatively new one historically. Remember that most of those grassy areas today used to be woods until we humans cut all the trees down and eradicated all the shrubs and other plants so that we could run livestock on pastures. Go look at some of those animated deforestation maps of Europe for example. Same thing with the US. Wherever modern humans settled, they turned woodland areas and diverse mixed biotopes into grass pastures until today, we are dealing with an incredible amount of grass in most areas with human civilization. But reality is, that this grass dominated lawn type stuff that we grow commercial orchards on these days, or what most people grow their home orchards on, that grass dominated lame approach is a very modern development. Go a few hundred years back and things get way more diverse, shrubby, herby, flowery, with all sorts of funky food plants in between. So I think it is a lot more safe to say that our messed up modern approach to fruit tree cultivation is slowly rediscovering the benefits of a diverse and supportive understory in our orchards. It is in no way a new concept. Humans just got stupid for a while.
