QUORUMAG

Australian Onion Conference · Devonport, 2–4 December

Learn to listen.

What the onion has been trying to tell you: Steve Martin’s talk at the onion industry’s conference, the gist of it, and a way to put it to work on your own onions.

Plan your onions with Steve’s program Meet Steve

From the talk

Your biggest yield loss happens before you can see the bulb.

Steve, on where the yield goes

Every mineral decision is a hormone decision.

Steve, on what goes on the crop

Thrips are not a spray problem. They are a nutritional signal.

Steve, on the pest that tells you most

The problem

The ceiling is set early.

An onion builds its bulb in two goes. First it decides how many cells, and so how many rings, the bulb will have. Then each cell fills.

The first sets the most the bulb can be, and it closes weeks before there’s a bulb to see. The second only fills what’s already there. Feed the second before the first is done, and the rings you lost don’t come back.

That’s why the talk spends its time on the stages, and on one mineral in particular: potassium, which fills cells, and is at its most costly when it goes on before calcium has built them.

Watercolour of two brown onions cut across: a large one crowded with thin, tight rings, and a smaller one with fewer, thick, watery rings.

The answer

Five stages, not a calendar.

Steve calls them the critical stages of influence. Each one asks for something different, and each one shuts. These are his for onions, and the days run from sowing.

  1. Watercolour of an onion seedling at the flag stage, its black seed coat still on the tip, the first leaf showing and one root down.

    CSI 1 Days 0–20

    Root establishment

    “Build the cytokinin factory before anything else.”

  2. Watercolour of a young onion with three or four upright leaves on a slim white base, and a small fan of roots.

    CSI 2 Days 20–50

    Vegetative structure

    “Build a dense, disease-resistant leaf base. Quality over speed.”

  3. Watercolour of an onion in full leaf, its canopy of tall green leaves over a slim neck.

    CSI 3 Days 50–80

    Canopy development

    “Bank the maximum number of healthy green leaves.”

  4. Watercolour of an onion as its bulb begins: a small white swelling at the base of the leaves, at the soil line.

    CSI 4 Days 80–120

    Bulb initiation and cell division

    “The plant decides how many cells the bulb will contain. This is the yield ceiling.”

  5. Watercolour of an onion with a round bulb filling out at the soil line, under its leaves.

    CSI 5 Days 120–180

    Bulb fill and maturation

    “Now potassium is earned. The cell-division window is closed.”

“If the bulb is below 4 cm, potassium stays in the shed.”

Steve’s one rule for the handoff from calcium to potassium

The proof

The plant will tell you.

A sap test is how you hear it: the young leaves and the old ones sampled separately, and read together.

It shows whether the nitrogen in the plant has become protein, whether potassium is running ahead of calcium, and whether the growing point is still getting what it needs. In Steve’s words, “10–14 days before any visible symptom. That’s your window of opportunity.”

Try it on one block

Run the program on part of a block and grow the rest as you always have, then let the pack-shed figures decide. As Steve puts it: “Either way: leave a check strip. The best proof is the crop you grew yourself.”

Your onions

Plan your season around its stages.

The free program builder starts your onions from Steve’s own program: the five stages, what each one needs, and where a sap test goes. Change it to suit your farm, then print it for the shed wall.

Start your onion plan Steve on your farm

Want Steve at your own field day? See his talks, or drop him a line about your onions.

Watercolour of one firm brown onion on a weathered timber table in the light of a shed doorway, with two more and some loose skins behind.

You don’t have to take my word for it. The plant will tell you. Learn to listen.

Steve Martin