AusBonsai

Recent hot day in Melbourne caused a few casualties which has been quite depressing.

Since the hot weather I have noticed this on some of the azalea, particularly those that were scorched by the 40+ degree day.



What we are looking at and concerned about is the yellow mottling of the leaves, especially the new growth. The burnt tips etc are not a problem, I expect them to drop off next year.

Is it a deficiency as a result of hot weather?

They are growing in a mix of 50% pine and a 25% perlite 20% sand and 5% zeolite and are fed with 9 month osmocote and seamungus.

I would really like some help on this as it will be one less thing to stress about.

It's a lacebug infestation. Turn over the leaf and on the underside you will see many dark speckles, which are the droppings of the insect. You may also see the insect itself. Spreads very quickly. If you enter "lacebug" in Google, you'll find images of this plague that look just like the leaves of your own Azalea. Treat with Confidor, asap. Formerly treated with Malathion, but the insect has become resistant against this.
Good luck!

Lisa

Hi Damian,
Lisa is correct in her analysis and treatment. Don't forget that Azaleas like acidic soil. My suggestion would be not to use Seamungus and use the Osmocote that is for Azaleas. Get some Miracle-Gro for Azaleas. This can be used on Azaleas for both foliage and soil feeding.

Regards Ray

I give all my azaleas ( and anything else nearby ) a spray with Confidor 2 -3 times a year.

Thank you but sorry guys, I am well aware of the evil lace bug and thrip and what they can do. If you are familiar with the effect that these critters create then small white dots as a result of damage on the underside of the leaf from feeding would be clearly evident, you would see those small white dots in profusion. The Azalea in question are not heavily affected by lace bug or thrip.
However, the photo is not that good
In this case I am asking about the yellowish mottling of the younger leaves.
Still looking for answers

In relation to seamungus I find it quite suitable for Azalea as a top up feed not as a pure diet, I have yet to try the Kahoona :lost

As for confide, it is nasty stuff and I avoid it unless absolutely necessary.

Maybe iron deficiency

I would have gone with a thrip or the like as well, but since you say there is no evidence of any nasties, then I'd go with a stress induced problem. As suggested by Ray, I'd grab a box of Miracle-Gro for Azaleas and give them a good feed.

As an indicator of how good this stuff is, I recently purchased 6 Azalea's from the Big Green shed. Just so you know their condition, 6" pots and they cost me the princely sum of $2.01 each. In the simplest form, they were crook . Got them home, mixed up a dose of Miracal-gro and gave them a good soak. Couple of weeks later, green as grass and even a few flowers. Would take pic's for proof, but you might be aware we have had a little tad of rain up here over the past few weeks and the flowers have washed away.

"If your not using Miracle-Gro on your Azaleas, you bloody well should be"

The first, and biggest problem here is that it is an azalea One of the hypochondriacs of the plant world.

The pics are not really clear enough to get an accurate idea of what is afflicting these but nutrient deficiencies are quite common with very open soiless mixes. The 9m osmocote is probably about exhausted now though the seamungus should be supplying nutrients. Deficiency symptoms only in younger leaves indicate an immobile element - iron or manganese????
Mottled leaves can also indicate virus infection but I don't know what virus, if any, affect azalea.
Because these are azaleas have you checked pH of the mix? Some mixes can change pH as they age or from reaction with nutrients.

Sorry no definite answer, only possibilities Damian.

That I will look into. If there are any other possibilities I am still thirsty for them. The more there are the better I can sort this out.

I agree with Sno on the iron deficiency. Symptom: interveinal chlorosis of young leaves. If one magnifies your photo one can see that the veins of your plant are still a normal green. It is difficult to make out, as there is also lacebug damage, unless I am much mistaken. The advice is to spray the plant with chelated iron. If the leaves turn green after a week then iron deficiency is the cause. However, the permanent remedy is then to lower the pH of the soil.
Knowledgeable as you are, and with such a wealth of info on Azaleas available on the Internet, I am sure that this deficiency must have occurred to you, so I mention it here mainly for other azaleea growers. See http://azaleas.org/index.pl/azdiseasetext.html I thought the tip of spraying with iron chelate quite handy.

BTW, what does that label say? IANELLA RE.... Is that part of the name of your Azalea?

BTW #2: I agree with you that "confide" (I take it you mean Confidor) is nasty stuff, being a systemic pesticide, even if it is supposed to be less nasty than others. If you have an alternative method of eradicating lacebug, please let us know. I have had limited success with homemade white oil, with tea tree oil replacing the usual cooking oil.

Lisa

shibui wrote:The first, and biggest problem here is that it is an azalea One of the hypochondriacs of the plant world..

Ain't that the truth!

Hackimoto wrote: Ain't that the truth

And i concur

Believe it or not there is no lace bug damage on that Azalea
There are other ways to control the little critters. Depending on how much Azalea stock you have and how quick you can get to them, manual removal is easy if you have just a few specimens when the problem first presents.
A method which I use is to keep your Azalea in a sunny position and keep the foliage crown open. You must keep the plant healthy and well watered. Lace bug may still occur in the lower/older leaves but the environment in the upper leaves tends to be unsuitable and the upper leaves will harden up a bit more. I have found that if the plant is in shade the foliage is softer and more prone to attack. Sometimes severe attack can tip a plant over the edge and kill it.

Neem oil has been touted as a effective pesticide but I have yet to try it out.

I purchased iron chelate today along with magnesium sulphate, I will try out both on similarly affected plants so I can isolate the problem a little easier. It seems that the lines between iron and magnesium deficiency are a little blurred. My guess after yesterday's suggestions and some research is that iron deficiency is the problem.

I will take some more photos and post some before and after for future reference.

Thanks for your help guys

bodhidharma wrote:

Hackimoto wrote: Ain't that the truth

And i concur

For all of the press that these plants get for being tough and easy plants to look after that quote is true.
It seems that the best way to grow them is to find a horribly exposed position and leave them to it. I see so many around Melbourne that survive for 50+ years in full sun (the usual survivors are Kurume though).

Can't find the miracle gro for Azalea

The Big Green Shed stocks it if you have one near you, mate.