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How to treat Grevillia die back?

my grevilias are all of a sudden wilting then dying. They did amazing after a large tree was removed and they received sunlight. They grew twice their size in a matter of months and even flowered. They are in sandy soil but at planting about a year ago we added cow manure. Well before the tree was cut down. They were fabulous. Then all of a sudden one began to wilt and has died but now we notice the 2nd one is wilting. It's been a long time since we added the cow manure. I'm hoping to save them. Is this the problem. There were three trees all in a row on the northern side between properties.

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EricL

Hello @BulaFiji

Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about your Grevilleas.

It sounds like your grevilleas were thriving after getting more sunlight but are now suddenly struggling, which can be frustrating. Given that they took off so well after the tree removal and were doing great for months, it’s unlikely that the cow manure from a year ago is the problem. That would have broken down long ago, especially in sandy soil. Instead, sudden wilting followed by death suggests root stress, which could be from fungal disease, pests, or even environmental changes.

One of the most common culprits for this kind of rapid decline in grevilleas is root rot, which thrives in moist soil and attacks the roots, making it impossible for the plant to take up water. Even in sandy soil, heavy rain or poor drainage in certain spots can trigger it. If that’s the issue, treating with Yates Anti-Rot Phosacid can help strengthen the plant’s natural defences.

Since these were planted in a row, it’s also worth considering whether the tree removal changed the wind exposure or soil conditions, making them more vulnerable. If the roots were suddenly exposed to more heat and drying, they might have become stressed. Watering deeply but infrequently and applying a light mulch like sugar cane or pine bark (rather than anything too rich) could help keep the remaining plants stable while they recover.

If the second one is wilting, acting quickly with a root treatment like Seasol might give it a better chance of survival. If you notice any soft or discoloured areas at the base, removing the worst-affected parts and improving drainage around the roots could slow down further decline.

If you need further assistance, please let us know.

Eric

BulaFiji

Hello again,

Thank you for the past info. I did as suggested but alas two of the 3 died. Trying again

Can you tell me what's happening g to my passion fruit. It's grown beautifully, first year no fruit yet but one large branch has died off and the cane looks eaten or something. Do you know what's wrong.

Also my lime tree has been growing beautifully with fruit but all of a sudden it looks very sick. Can't fathom tne reason. The new leaves look pale and sickly.

Thanks for any help, photos below

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/52208#Comment_52208

Hi @BulaFiji,

Sorry to hear about the losses, but good on you for giving it another go.

With your passionfruit, did you notice whether the plant had been flowering much? Sometimes you can get lots of leafy growth but little to no fruit, especially in the first years. Passionfruit can be a bit fussy when it comes to fruiting — things like lack of pollinators, not enough sunlight, or too much nitrogen in the fertiliser can all play a part. As for the large branch dying back and the stem looking like it’s been eaten, could this section have been previously rubbing against the fence? It looks more like abrasion damage, but it could be a rat having a chew.

Regarding your lime tree, how long ago was it last repotted? And what’s your current fertilising routine like? Pale new growth can often point to a nutrient deficiency, commonly nitrogen or iron. Since it’s in a pot, it could also be root-bound, or the soil might be exhausted. A good citrus fertiliser in the warmer months, plus some trace elements, can usually perk things up — but it’s worth checking the root health if it’s been in the same pot for a long while.

Please let me know if you have any questions.

Mitchell

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