Host crops keep fungi; long brassica or fallow sequences starve them

Many vegetables, grasses, and fruit plants host arbuscular fungi. Several cabbage-family crops, beets, spinach, and mustards generally do not. A long stretch of those non-hosts, or a bare fallow, can drop the living network before you plant a crop that needs it.

You can still grow cabbage. Plan the next step: a host cover or a strongly mycorrhizal cash crop after the non-host season, so the fungi have roots again.

Do not treat this as a banned-crop list. It is a rotation order. If the following tomato or onion row struggles after a long brassica block, missing fungal partners are one place to look — along with soil, water, and seed.

In this series

• Fungi need living roots, air, and moisture — a bag is not a soil
• Put inoculant next to the seed or the transplant root
• Too much phosphorus can turn the partnership off
• Host crops keep fungi; long brassica or fallow sequences starve them
• Tillage, compaction, and waterlogging break the network
• Match the fungus type to the plant — vegetables are not pines