Hi, I could share some experience and ideas.

First of all, I would add some extra conditions to CCrops in orchards:

– if possible to be self-sown or perennial so reduce costs to maintain

– to cover winter and very early spring, when leaves are absent or small and we can avoid shadow, which could be very suppressive during the main season

– to improve soil compaction and infiltration made by machines

– If possible to grow well after spreading on the surface instead of sowing with a drill.

It is not possible for one cover crop to respond to all the needs. we need successions of plants. What we practice is to let nature decide what is best. though first 1-3 years could be problematic and need some intervention. This is how we found out wild winter vetch could be a wonderful cover crop. See pic 1 and 2, done today. It spreads alone quite fast only after 1 year. The mistake I noticed we do is to apply early mowing in the spring and not let the winter mix produce seeds. A very low mowing could also be detrimental and I recommend to be avoided.

The same practice provided me with “weed” I diagnose as Picris altissima or P. echioides, you can see dry plants over vetch, pic. 2. From mid-May (South Europe) till frost it can grow and suppress other weeds to a high extend. Abundantly and for long time blooms, does not depend on sunlight intensity, produces a lot of seeds and small rosettes even now in winter. It has quite hairy and leather-like leaves, the first species seems to originate from warm regions, I feel it is efficient in water use.

Besides we tried to spread in the autumn on the surface weeds from rye, wheat, and barley. The last one seems to be most adaptive and second year it thrives quite nicely, pic. 3. Barley is nice for P uptake, as far as I know, produces tillers a lot and ripens earlier i.e. f we may mow In mid-May.

White clover seems quite a shadow and compaction tolerant in cherry plot, develops well interrow, but not vigorous enough to compete in the row.

Medic is nice just before the dry and hot season.

Phacelia I love a lot due to upper soil layer structuring, nice blooming and bees attraction, average size competitive plants growing well in a mix. I have an impression it produces a lot and easily self reproduced in the field.