Py-Bo has a 1-day withholding period on edible plants. That is the harvest-close slot: spray today, pick tomorrow. It is the reason growers keep a bottle of natural pyrethrum in the shed when they cannot wait out a longer withhold.
This page is for commercial Australian growers (and anyone searching pyrethrum 1-day withholding, spray today pick tomorrow, or Py-Bo 1L / 5L). Py-Bo is 80 g/L pyrethrins + 320 g/L piperonyl butoxide, APVMA 53738. Mix 1 mL per litre of water. It is a contact spray: it kills named insects it hits, then UV breaks the pyrethrins down. Always read the current APVMA-approved label. The label is the law.
Buy Py-Bo from Pestech (250mL $89, 1L $226, 5L $1,040, 20L $4,060 inc GST) or ask at Nutrien Ag, E.E. Muir, Elders, Lindsay Rural or Fernland. A 10 mL sample is how most people see knockdown before they commit a tank.
What 1-day withholding actually means
Withholding period (WHP) is the legal gap between the last spray and harvest of edible produce. On Py-Bo, that gap is one day for fruit and vegetable crops named on the label. It is not a residue “protection” interval. Pyrethrins degrade in sunlight. After a few hours of UV they are gone from the leaf. That is why multi-pick crops can use it close to harvest, and why you re-treat on the next hatch rather than expecting weeks of cover.
- Last spray this afternoon → harvest from tomorrow on labelled edible crops.
- Spray after sundown when you can: better contact, better on bees (see below), and UV has not already stripped the spray.
- A 1-day WHP does not mean the insects stay dead for a week. Eggs, pupae and insects you missed are still in the block.
When the 1-day slot is the job
Use it when you still have a labelled pest on the plant and harvest is too close for a longer withhold. Typical cases: aphids or whitefly on a pick, thrips in flowers or tips, caterpillars still on the leaf, leafhoppers, earwigs, ants on the crop. Coverage is the work — undersides, tips, the far side of the row. Missed tissue equals live insects tomorrow.
Named horticultural pests on the Py-Bo label: aphids, ants, cabbage moth and other caterpillars, earwigs, leafhoppers, thrips, whiteflies, on fruit and vegetable crops, cut flowers and ornamental plants. That list is the law. This page does not authorise off-label use on unnamed pests or unnamed tree crops.
Pyrethroids are not pyrethrins
Resistance that stops a spray program is a man-made pyrethroid story (the “-thrin” residuals: bifenthrin, permethrin and the rest). Those sit on the leaf and keep selecting. Natural pyrethrins in Py-Bo are the six esters from the daisy, with PBO. They knock down on contact, then UV breaks them down. Field resistance to pyrethrum at a level that wrecks control has been rare. If a pyrethroid has already failed on the block, that is not a reason to assume pyrethrum will fail the same way. Coverage still decides it: if you do not hit them, they do not die.
Py-Bo is 80 g/L pyrethrins. You will not find a stronger pyrethrum concentrate. Mix 1 mL per litre: 1 L makes 1,000 L of spray, 5 L makes 5,000 L.
Rate, coverage, bees
- Rate: 1 mL/L (100 mL/100 L). 1 L of Py-Bo makes 1,000 L of spray. 5 L makes 5,000 L.
- Contact only: droplets have to hit the insect. It is not systemic and it is not a bait.
- Bees: do not spray plants in flower while bees are foraging. Apply after dark. Residues can still keep bees off treated surfaces into the next morning until UV degrades the pyrethrins.
- Workers: once the last droplet has cleared, re-entry is short. That is the other harvest-close job: people still in the crop.
Py-Bo pack sizes (buy from Pestech or a farm store)
| Pack | Mixes about | Price inc GST |
|---|---|---|
| Py-Bo 250mL | 250 L | $89 |
| Py-Bo 1L | 1,000 L (1 IBC) | $226 |
| Py-Bo 5L | 5,000 L (5 IBCs) | $1,040 |
| Py-Bo 20L | 20,000 L | $4,060 |
We post Australia-wide. If you want to see it on the counter, ask at Nutrien Ag, E.E. Muir, Elders, Lindsay Rural or Fernland. Take a 10 mL sample, mix into 10 L, spray a few infested plants with your usual gear, beat sheet before and after. Knockdown is in minutes if you hit them.
FAQ
What is the withholding period for Py-Bo?
One day on edible plants named on the label. Spray today, pick tomorrow. Always check the current label for the crop you are picking.
What is the mix rate for Py-Bo / pyrethrum concentrate?
1 mL of Py-Bo per litre of water for the horticultural uses on the label.
Can you spray pyrethrum on fruit and vegetables?
Yes, on fruit and vegetable crops named on the Py-Bo label, at 1 mL/L, with a 1-day withhold. It is a contact spray. Do not treat it as a licence for every pest on every crop.
How long does pyrethrum last on the plant?
Not long in sunlight. Spray after sundown for the most impact. By the next morning much of the residue is gone. That is the 1-day withhold, and it is why you do not get weeks of residual control.
Where do I buy Py-Bo 1L or Py-Bo 5L in Australia?
From pestech.com.au, or ask at Nutrien Ag, E.E. Muir, Elders, Lindsay Rural or Fernland.
Related: Py-Bo product information · Aphids and thrips spray timing · Cabbage moths and other caterpillars