Hi,
What is that white substance on bark of this curry plant ?
My other curry plants seem fine.
Hello @nigelfds
That white substance on the bark looks very much like a scale insect infestation, most likely a white scale or louse scale rather than a fungal issue. The way it is clustered tightly along the stems and trunk is very typical of scale insects, which attach themselves to the bark and suck sap from the plant. The slight yellowing on some of the leaves also supports this, as scale can weaken the plant over time and reduce vigour.
The good news is that your curry plant still looks recoverable and the infestation appears manageable if you act early. Scale often appears when plants are stressed from inconsistent watering, limited airflow, overcrowding, or fluctuating temperatures. Curry plants in pots can sometimes become more susceptible if they dry out too much between watering or sit in humid sheltered areas with poor air circulation.
The first thing I would do is gently wipe or scrape as much of the white scale off the bark as possible using a soft cloth, old toothbrush or even your fingernail. Removing the bulk of them manually makes treatments much more effective. After that, spray the entire plant thoroughly, especially the stems and undersides of leaves, with a horticultural oil or eco oil product. These work by coating and suffocating the insects rather than using harsh chemicals, which is ideal for edible plants like curry leaf. Scale insects are commonly treated with white oil or eco oil products.
A very good option available through the store is https://www.bunnings.com.au/ocp-750ml-ready-to-use-eco-oil_p2961639 . Another suitable option is https://www.bunnings.com.au/yates-750ml-ready-to-use-pest-oil_p2961088 . If the infestation becomes stubborn or you notice fungal issues developing as well, https://www.bunnings.com.au/yates-500ml-lime-sulphur-concentrate_p2962741 can also help, but I would start with the eco oil or pest oil first as they are gentler on curry plants.
When spraying, do it in the cooler part of the day, either early morning or late afternoon, and avoid spraying during hot direct sun as the leaves can burn. You will probably need to repeat treatment every 7–10 days for a few weeks because newly hatched scale insects can keep appearing after the first spray.
I would also isolate this plant slightly from your other curry plants for now and inspect the others closely along the stems and leaf joints. Ants are another clue to watch for, as they often protect scale insects in exchange for the sticky honeydew they produce.
A couple of extra tips that really help with curry plants are to keep them in a bright sunny spot with good airflow, avoid wetting the foliage too late in the day, and occasionally give the stems a close inspection so you catch pests early before they spread. Once treated, your plant should bounce back quite well and produce healthy new growth again. Please remember to wear personal protection such as gloves, goggles and a mask.
If you need further assistance, please let us know.
Eric
Thanks Eric
I have this one at home : https://www.bunnings.com.au/yates-200ml-pyrethrum-insect-pest-killer-concentrate_p2961583 will this work ?
Pyrethrum alone is generally not effective at killing mature, established scale insects. While it works as a fast-acting contact insecticide for many pests, it cannot penetrate the hard, waxy protective shell that adult scales develop. I suggest using https://www.workshop.bunnings.com.au/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.bunnings.com.au%2Focp-750ml-ready-to-use-eco-oil_p2961639 or https://www.workshop.bunnings.com.au/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.bunnings.com.au%2Fyates-750ml-ready-to-use-pest-oil_p2961088 to manage the scale infestation.
