Natural aphid spray: Py-Bo pyrethrum for crops, orchards, veg and gardens
Aphids on the new growth? Py-Bo is a natural pyrethrum concentrate that kills aphids on contact. Aphids are a named pest on the Py-Bo label for fruit and vegetable crops, cut flowers and ornamental plants. Mix 1 mL per litre of water (100 mL per 100 L), wet the colonies, and on labelled edible crops you can pick the next day (1-day withholding period).
Buy Py-Bo: 250 mL, 1 L, 5 L or 20 L · or ask at Nutrien Ag, E.E. Muir, Elders, Lindsay Rural or Fernland.
Py-Bo Natural Pyrethrum + Piperonyl Butoxide Insecticidal Concentrate, APVMA 53738: 80 g/L pyrethrins + 320 g/L piperonyl butoxide. Always read the current label. The label is the law.
How Py-Bo controls aphids
Py-Bo works by contact. The spray droplet has to land on the aphid. Natural pyrethrins (the insecticidal esters from the pyrethrum daisy) act on the insect’s nervous system and give a fast knockdown. Piperonyl butoxide (PBO) is a synergist: it helps the pyrethrins do their job by slowing the insect’s ability to break them down.
Py-Bo is not systemic and does not move in the sap. Sunlight (UV) breaks pyrethrins down within hours, so there is no long residue sitting on the crop. That short life is the reason for the 1-day withholding period on labelled edible plants. It also means one spray won’t protect new growth for weeks. You spray the aphids that are there now, then check again.
Label rate for aphids
From the Py-Bo label directions for use:
| Situation | Pests | Rate | Critical comments |
|---|---|---|---|
| Fruit and vegetable crops, cut flowers and ornamental plants | Aphids, ants, cabbage moths and other caterpillars, earwigs, leafhoppers, thrips, whiteflies | 1 mL in 1 L of water or 100 mL in 100 L of water | Mist or spray to contact the pests when infestation occurs. Thorough coverage of all foliage including undersurfaces is essential. |
- Withholding period: edible plants, do not harvest for 1 day after application. See Py-Bo 1-day withholding: spray today, pick tomorrow.
- Bees: dangerous to bees. Do not spray any plants in flower while bees are foraging.
Don’t lift the rate to make up for poor coverage. If aphids are still alive after the spray has dried, the droplets missed them.
How far a pack goes at 1 mL/L: 250 mL makes about 250 L of spray, 1 L makes about 1,000 L, 5 L makes about 5,000 L and 20 L makes about 20,000 L.
Where you can use it
The label situation is fruit and vegetable crops, cut flowers and ornamental plants. For aphids that covers:
- Orchards and fruit: stone fruit, pome fruit, citrus flush, berries and other fruit crops.
- Vegetables: brassicas, leafy greens, tomatoes, capsicum, cucurbits and other vegetable crops.
- Cut flowers and ornamentals: roses, nursery stock, bedding plants and garden ornamentals.
Check the pack in your shed for your crop before you mix. Always read the label on the pack and follow the rate and directions for your situation.
Getting coverage right
Aphids hide where sprays miss. They sit on soft tips, flower stalks, the undersides of young leaves and inside curled leaves.
- Hit the colonies. Aim at growing tips, new leaves and flower buds, and wet the undersides. The label says thorough coverage of all foliage including undersurfaces is essential.
- Open the canopy. Spray from both sides of the row and into the centre of trees. Check the far side of the plant.
- Curled leaves are hard. Aphids inside a tight curl may survive. Catch colonies early, before the leaves roll.
- Look again. Aphids give birth to live young and can build a new colony in about a week in warm weather. If the infestation comes back, spray again at the label rate when you see live aphids.
- Check the result. Dead, shrivelled aphids mean you hit them. Live ones mean coverage needs work: change nozzle angle, water volume or ground speed.
When to spray: dusk, and look after the bees
Pyrethrins are dangerous to bees. Do not spray any plants in flower while bees are foraging. The practical answer is to spray at dusk or after dark, when bees are back in the hive. A late spray also gives the pyrethrins the night on the leaf before sunlight breaks them down.
Contact sprays also kill ladybirds, lacewings and hoverfly larvae they hit. Spray when aphid numbers justify it, rather than as a weekly cover spray. Because the residue breaks down quickly, beneficials can move back onto the crop soon after.
Spray today, pick tomorrow
On labelled edible plants the withholding period is 1 day. That suits multi-pick crops such as tomatoes, cucumbers, capsicum, beans, leafy greens and berries, where aphids often turn up close to harvest. Read more on the 1-day withholding page.
Pyrethroids are not pyrethrins
The names sound alike, but they are different chemistry. Pyrethroids are man-made insecticides built to last longer on the leaf. Repeated use has bred pyrethroid-resistant pests that can wreck a spray program. Pyrethrins are the natural esters in pyrethrum. Py-Bo pairs them with the PBO synergist, and they break down in sunlight within hours.
Natural pyrethrins don’t have the resistance problems pyrethroids do. Py-Bo is a contact spray, so it has to hit the insect to kill it. If you’re not getting the kill rate you want, change the spray application, direction and droplet size. That’s what makes the difference.
What Py-Bo won’t do
- It won’t kill aphids the spray doesn’t touch, such as aphids in tight curls, on the dry far side of the tree, or under the dense wax of woolly apple aphid. It is not a root treatment.
- It won’t give weeks of residual protection.
- It won’t undo virus already spread by aphids.
- It won’t get through the wax on scales and mealybugs. A contact spray has to reach the insect.
Break the life cycle: aphid and thrips spray timing
Py-Bo kills by contact. If the droplet does not hit the insect, the insect does not die. It is not systemic. It is not residual in the plant. UV breaks pyrethrins down in a few hours of sunlight — that is why the withholding period is one day, and why you re-treat on the next hatch, not on a six-week “protection” interval.
For follow-up spray timing on every Py-Bo label pest (aphids, thrips, whiteflies, leafhoppers, caterpillars and earwigs), see Break the pest life cycle: timing Py-Bo follow-up sprays.
Thrips in the same flowers
The label names thrips. Adults are tiny (about 1–2 mm), slender, with fringed wings. A 10× lens helps. They rasp and suck on petals, stamens, young fruit, growing tips and the undersides of new leaves. Damage is silvering or bronzing of new growth, scarred or russeted fruit, distorted flowers, and — when they swarm in blossom — poor set.
Plague thrips (Thrips imaginis) is the native flower thrips that swarms Australian pome and stone fruit blossom, strawberries and many ornamentals. They fly in from weeds and native vegetation when pale flowers open. Western flower thrips (Frankliniella occidentalis), onion thrips, chilli thrips (Scirtothrips dorsalis) and Kelly’s citrus thrips (Pezothrips kellyanus) are other named-group species on fruit, vegetables, berries and ornamentals. Identification still matters for monitoring. The spray claim is thrips the droplets can hit.
Eggs are inserted in plant tissue. Larvae feed on the plant. Pupae are often off the crop — in soil, debris or protected sites. Adults fly. Generations overlap. A spray that knocks adults and larvae on the flower does not kill eggs already in the tissue or pupae in the soil. The same rate (1 mL/L), dusk timing and coverage rules apply as for aphids. For citrus, see Citrus aphids, thrips and whitefly.
Life cycle (what you are spraying, and what you are not)
| Stage | Where | Rough timing | Hit by a foliar contact spray? |
|---|---|---|---|
| Aphid egg (overwintering, some species) | Bark, buds, crevices | Hatch at budburst | No — not a feeding target, and often already hatched when you see colonies |
| Aphid nymph / live young | Tips, flowers, young leaves; inside curled flush | Days; generation ~1 week in warmth | Yes, if droplets contact them. Inside a tight curl: much harder |
| Aphid adult (wingless) | Same surfaces | Continuous on flush | Yes, if contacted |
| Aphid adult (winged) | Leaving or arriving | When crowded or flush hardens | Only if droplets hit the insect |
| Woolly apple aphid under wax, or on roots | Wool at wounds; roots | Season-long | Poor through dense wool. Roots: no |
| Thrips egg | Inserted in petals, leaves, fruit tissue | Hatch in a few days in warmth | No |
| Thrips larva / nymph | Flowers, new growth, undersides, calyx, fruit-touch points | Days | Yes, if coverage reaches insides of flowers, tips and undersides |
| Thrips pupa | Often soil, litter, protected sites off the crop | Days | No |
| Thrips adult | Flowers, flush; flying in from weeds and natives | Days; swarms at bloom | Yes, if contacted. Disturbed adults fly off |
| Mites | Leaves, buds | — | See label; contact only |
| Rutherglen bug | Fly-in swarms on flowers, fruit, seed | — | See label; contact only |
Beneficials (ladybirds, lacewings, hoverfly larvae, parasitoids, Orius) eat aphids and thrips. They are support, not a commercial guarantee when blossom is full and a swarm has arrived. A contact spray will also kill beneficials it hits.
Spray timing through the season
Spray when aphids or thrips are on the plant and you can see insects or fresh damage. Contact insecticides only kill what they hit. Eggs in tissue, pupae off the crop, aphids inside a tight curl, and insects on the dry far side of the tree keep the cycle going.
- Scout from budburst. On most tree crops the flowers open before the leaves. Aphids are already deciding the new growth is food. Flower thrips (especially plague thrips) can be in the blossom the same week the bees are.
- Do not wait for a plague. Spray when numbers are up a little, and throughout the block — not after honeydew is running and fruit is russeted.
- Coverage is the job: growing tips and the inside of curled leaves for aphids; insides of flowers, undersides of young leaves, calyx and fruit-touch points for thrips. Missed tissue equals live insects.
- A spray that kills aphids on the tip does not kill the next live young they would have produced, and it does not kill thrips eggs already in the petal. Aphids can rebuild in about a week. Thrips eggs can hatch in a few days.
- Plan a follow-up when the next hatch or fresh insects are visible — often inside a week at peak bloom or summer flush. Do not treat Py-Bo as a six-week “protection” interval.
- Whiteflies, leafhoppers and surface caterpillars often build after there is more leaf. They are named pests too, but they are a later scouting job.
- Systemic insecticides need leaf area to be taken up. At budburst and early bloom there often is not enough leaf. That is why a contact knockdown on the insects you can see is the job now. If you use a systemic later, that is a separate label — not Py-Bo.
Read the result. Py-Bo knocks labelled contact pests in minutes. If you see dead aphids and thrips, droplets hit them. If you see live ones after the spray has dried, they were not contacted — change droplet size, pressure, nozzle angle or speed on a test run. You cannot kill them any deader than dead. Do not raise the rate above 1 mL/L to make up for a dry underside or a missed flower.
Mites and Rutherglen bug
The old Tree Crop copy listed mites (spider mites, rust mites, bud mites) alongside aphids and thrips, and mentioned swarms of Rutherglen bugs (Nysius vinitor) flying in at flowering. A swarm of Rutherglen bugs at flowering is a real crop problem. Py-Bo is a contact spray, so the same rule applies to anything you spray: it has to reach the insect. The Py-Bo label covers three situations (fruit and vegetable crops, cut flowers and ornamentals; buildings including agricultural sheds; outdoors for flying insects). Always read the label on the pack and follow the rate and directions for your situation.
Buy Py-Bo natural pyrethrum
Py-Bo comes in 250 mL, 1 L, 5 L and 20 L. That’s enough for a home garden or a full orchard block at 1 mL/L.
Buy Py-Bo online, or ask at Nutrien Ag, E.E. Muir, Elders, Lindsay Rural or Fernland. More on the product: Why Py-Bo. Questions: Freecall 1800 12345 7.
Aphid spray FAQ
Is Py-Bo a natural aphid spray?
Yes. Py-Bo is a natural pyrethrum concentrate: 80 g/L pyrethrins from the pyrethrum daisy plus 320 g/L piperonyl butoxide (PBO) as a synergist. Aphids are a named pest on its label for fruit and vegetable crops, cut flowers and ornamental plants (APVMA 53738).
How much Py-Bo per litre for aphids?
The label rate is 1 mL of Py-Bo in 1 L of water, or 100 mL in 100 L. Spray to contact the aphids, with thorough coverage of all foliage including the undersides of leaves. Don’t raise the rate.
Can I spray aphids and pick the next day?
On labelled edible plants the withholding period is 1 day: do not harvest for 1 day after application. Spray today, pick tomorrow. Always confirm your crop on the current label.
Is Py-Bo safe for bees?
No. The label says it is dangerous to bees. Do not spray any plants in flower while bees are foraging. Spray at dusk or after dark when bees are in the hive.
Will one spray get rid of aphids for good?
No. Py-Bo kills the aphids it contacts and then breaks down in sunlight. It leaves no long residual. Aphids can rebuild in about a week in warm weather, so check again and re-spray at the label rate if a new infestation appears.
Can I use Py-Bo on citrus, roses and vegetables?
Yes, for aphids. The label situation is fruit and vegetable crops, cut flowers and ornamental plants, which covers citrus, roses and vegetables. Check the label on your pack for your crop before you mix.
Is pyrethrum the same as a pyrethroid?
No. Pyrethrins are the natural insecticide in pyrethrum and break down in sunlight within hours. Pyrethroids are man-made, longer-lasting chemicals. Natural pyrethrins don’t have the resistance problems pyrethroids do. Py-Bo is a contact spray, so it has to hit the insect to kill it. If you’re not getting the kill rate you want, change the spray application, direction and droplet size.
Always read and follow the current APVMA-approved label. The label is the law.