In simple organisms, you won't find a clear differentiation between what is above and what is below, or rather, between the nervous system and the reproductive system. In insects, you'll find a central nerve cord, but in mammals you'll find the nervous system centralized in the brain. Likewise, in creatures like shellfish you'll see a very simple organization where the boundaries are not clear at all. In fact, to eat shellfish, you must consume aspects of the digestive tract and even the reproductive organism. It is not without meaning that these have long been considered prohibited foods under kosher rules. Why? Because the body is a temple with a threefold division between the head, the chest, and the lower metabolic organism which are analogous to the external picture of the holy of holies, the inner temple, and the outer courtyard, respectively. The reproductive aspect belongs entirely outside of the temple grounds.
Man, as microcosm, is a reflection if the imago dei, the "image of God" and because the body is the host of the Spirit, it is a holy temple and should be treated as such. But anything that God makes must be a reflection of the divine world. Therefore, anything that man cultivates must also be a reflection of man as anything an artist creates is an expression of the artist. A farm as an organism likewise bears a reflection of the imago dei, though more concretely, it exhibits an expression of the individual personality of each individual farmer as that farmer interfaces with the unique landscape of any given region.
When we deal with fungus on the leaves of plants, this is an example of excessive ethericity reaching up where it does not belong. When Jesus drives the moneylenders and animals out of the temple, this is analogous to using Equisetum arvense to bring a healthy asceticism to plants, to starve out (so to speak) excessive inner planetary forces or lower animal impulses. There is a kind of harshness to Equisetum arvense inasmuch as it does not form true leaves, true roots, nor does it form true fruits or even seeds. In Equisetum arvense we have an image of Jesus driving out excessive lower metabolic forces which are quite healthy, but should only exist in the leaves as a sort of incense of a transmuted "burnt offering" and not as untransformed vitality. Leaves with too much vitality are experienced as a kind of substrate on which fungus can grow. When fungus grows on the leaves, this is an example of a displacement of an otherwise healthy process that is no longer properly contained.