Gall Wasp in Citrus Fruit

Rachel starts with ...
What is the best way to deal with Gall Wasp in Citrus trees?

Ian says...
Wasp traps can be purchaced from Bunnings Hardware stores for appx $8.00 ea in addition to removal of the galls, these traps ensure any missed are trapped and killed.

Mark says...
I have heard that in New Zealand they have a practise of cutting the "gall" somehow which kills the larvae without the need to prune the affected shoot. Does anyone know how this is done?

Sandy says...
Hi Everyone, We got a bit of advice of Don burke, pictured with myself, on left, and my daughter on right, at Flower Power Store, in Chadstone, back in October. Don mentioned about lea ving galls on citrus trees, if it didn't affect the tree much, or cut off affected bits and put them in the rubbish bin! Either way, seemed ok. What a wealth of Information is Don! He sure is a great bloke to talk about any gardening problems etc., you might have. I think I might try growing another citrus tree or two in pots next year!

Pictures - Click to enlarge
Picture: 1

Violet_Cactus says...
WASP TRAPS A DANGER TO NATIVE BIRDS!

I used to use the yellow plastic wasp traps, hanging them close to the trunk of my lemon tree. All was going well. Then my husband hung a trap on the orange tree, but he hung it among the blossoms, and not close to the trunk.

One afternoon we heard a terrible crying in the garden and when we looked out we saw a poor wattle-bird struggling across the lawn entangled in the sticky yellow thing off the orange tree, with half its tail feathers torn out.

I quickly captured the distressed little creature in a towel. It took ages to get the trap off, and when it came off it took the rest of the tail feathers with it, and some of the flight plumage too, and left that incredibly sticky glue all over the bird's feathers. The bird was sticking to everything and unable to fly.

I phoned around for a wildlife carer. That's when I discovered that most wildlife carers are wonderful, but one or two have the reputation of not deserving the name of 'carer'.

The best carer I found had no room for another animal so I handed over a hard-earned $500 for her to buy another aviary. She kept that bird for weeks, every day wiping its feathers with some kind of solvent to remove a little more of the glue.

Three times a week I would go to the local park to steal bottle brush flowers (I did not know where else to get them), then make the long drive to the carer's place to give the flowers to the bird.

The tail feathers grew at a very slow pace, though boosted by a high protein diet from the carer.

One day before the tail feathers were quite long enough, the bird, which had been stressed by captivity and was always trying to escape, flew past the carer's shoulder as she was putting food into the aviary.

It managed to fly high enough to perch in a tree, and then, rejoicing no doubt in its freedom, it flew off and was never seen again.
(Or if it was, I didn't recognise it!)

Moral: BE VERY WARY OF STICKY WASP TRAPS.
The carer told me that this kind of trauma to wild birds is not uncommon. She has seen it several times before and the Wildlife Carers as a group have called for the traps to be banned.

Violet_Cactus says...
JR, you say 'stuff the birds' but it's actually the birds who protect your trees.
They eat gall wasps and other malign insects.

Brendan says...
Hi irene,
The 'guru' up here recommends that you do not remove the gall wasps, as they will return big time when the new shoots appear.
For a detailed answer, go to: http://blogs.abc.net.au/queensland/capricornia_gardening_talkback_with_tom_wyatt/
and ask Tom the question. He usually answers on Fridays or Saturdays, of each week.

Mark says...
If it helps according to Colin Campbell from Gardening Australia:

"Another of the pests is this citrus gall wasp. The insect lays it’s egg in there and it all swells up so the hatching insect can get food. Now by law in Queensland, you have to prune that out and get rid of it before September when the adult hatches. "

http://www.abc.net.au/gardening/stories/s2273813.htm

JeneeVie says...
You can learn natural ways on how to get rid of wasps in this site http://waspsgone.com/.

Eliz says...
I understand that you can use a razor blade to shave off the surface of the gaul and expose and kill the lava. If the gaul has tiny holes in it, then it is too late. The lava have matured and escaped. Hope this helps.

MW says...
Hi guys.
I'm a technical agronomist heavily involved with the now industry and government funded control program targeting Citrus Gall Wasp and thought I'd be of some help here.
Firstly there is no pheromone available that will target Citrus Gall Wasp although work is being done. I have had numerous citrus growers contacting me regarding "pheromone traps" which has somehow stemmed from certain businesses in Melbourne and made it's way online. This is how a search linked me here. For those that are unsure how insect pheromones work it would pay to do some research. If you are finding adult Gall Wasp in traps it is purely coincidental and not related to any pheremones, colours, or attractants. If any of you have seen a heavily infested tree during adult emergence time there are literally tens of thousands of them all flying around at once. I have seen orchards that bad that the sky is nearly black with them. It's frightening! A pheromone suited for European Wasp for simply won't work on a Gall Wasp. Nearly all pheromones are species specific and nobody is yet to isolate a pheromone for Gall Wasp.
From a commercial perspective they are causing massive problems but even then over half of my enquiries are now from homeowners in regard to this pest.
The advice of removing galls is a good one. Adult wasps emerge from the galls around early to mid October. The wasps mate and lay eggs within the first few days of emergence and live for about a week. These eggs then hatch around early to mid December. The second the larvae emerge in the plant tissue they begin feeding. This feeding initiates a plant response (like a callous) and this gall becomes visible around March. They are poor fliers so tend to build up in an area and do localised damage. There are chemical control options that are relatively effective from a commercial perspective but the cost of these would be way too high for homeowners and aren't what you'd call "safe insecticides for home use" nor are they registered for that use (For example you'd need to buy a 10L drum at over $400 and use 9ml per tree). Even with certain chemical control options we are struggling to get on top of these pests. There are naturally occurring parasitoids but these are yet to establish themselves in southern Australia (remembering that Citrus Gall Wasp are a native pest of citrus and not an imported pest from another country). There are beneficial insect companies working on parasitoid release programs but it is a slow process and will take at least 10 years for them to even get remotely established. Keep in mind that even where these parasitoids ARE established Gall Wasp numbers still exploded over the last 4 years.
To help get on top of these pests will be a difficult exercise. From a homeowner perspective there is no point in attempting to control them in your own back yard if your neighbours aren't doing so as annual reinfestation will occur. They are weak fliers but will reinfest surrounding areas quite easily.
I'm more than happy to give more advice if needed but all I'd say is be wary of where your advice comes from as some of the theories I've heard are absolute garbage and shows a complete lack of understanding about this pest (and yes that includes some of the so called "garden gurus" in the media).
On another point we have thrown some of the nastiest insecticides on the market at these pests and they have pretty well laughed it off. Even if the adult gets a lethal dose and dies they have already laid their eggs through the cambium layer of the plant and the eggs have avoided any direct contact with the chemical. Only one chemical is available that can kill the pest in the egg phase and that is yet to be registered. The other chemical that has shown promise has no ovicidal properties and can only effect emerged larvae. Both have long withhold periods after application and both are ground applied and taken up via the root system.

MW says...
Hi Mark.
At this stage no rootstocks have shown to provide higher resistance than another (well not commercial rootstocks anyway). In fact the actual rootstock species if they have a sucker grow from them seem to be far more susceptible than the actual citrus graft.
The two chemicals that have currently shown to have a decent effect on Gall Wasp are both soil applied insecticides and are taken up into the tree via the roots. Neither at this stage are registered for Gall Wasp however one (Imidacloprid) is registered for Californian Red Scale and it just so happens that the timing for this particular chemical on Red Scale coincides with the perfect timing for Gall Wasp also (apply late November). Remember that I am not talking about the Imidacloprid (Confidor) that you'll find at Bunnings. I am referring to Confidor Guard which is a completely different formulation designed for soil application and root uptake (20 week withhold period after application). I won't mention the other chemical we are currently trialling but it is likely to be far more effective than Imidacloprid.
Unfortunately there is nothing that you can apply on the growth that will penetrate the bark to kill the eggs/larvae underneath (there used to be but it's no longer registered - far too dangerous). Bifenthrin sprays sprayed regularly over the tree through the wasp emergence period (every 3 days) will definitely knock them around however it is nearly guaranteed to flare up other pest species in the tree. It is however not registered for this use and not recommended. You WILL cause other pest problems and these can be difficult to control. You'll find that you'll get yourself wrapped up in a "chemical cycle" which is not something a backyard grower wants to get involved in as none of these chemicals you'll need are cheap and none are available in small amounts.
Slicing or cutting of the galls as mentioned is not a viable control option at all. If you do cut open a gall you will find that 99.9% of the time the eggs have been laid the whole way around the branch. Therefore you would need to basically ringbark the branch to expose the underlying eggs/larvae to the atmosphere. The best method for controlling this pest in a backyard is be vigilant and cut out new galls the second you see them. Once you let your tree become heavily infested it will be very difficult to get rid of as you have already probably found. Remember that every single adult wasp that emerges is capable of laying up to a few hundred eggs.
The link below is of a video I took the other week in a commercial Lemon orchard. Gall Wasp first appeared here around 18 years ago and these trees are now unviable.

https://www.youtube.com/watch?v=mt3H73AIJUI

I hope this helps in some way.

MAGGIELASS says...
yes, once you prune cut the gall in half that exposes them to oxygen and they die.

MW says...
Hi Mark.
Personally we haven't trialled Success Ultra but have trialled Success NEO. Success Ultra is simply the home gardener version of Success NEO. This is running the synthesized version of the original Spinosad from Dow(Spinetoram). It isn't systemic though. It does have some translaminar ability but limited xylem mobility and zero phloem mobility. The term "e;systemic"e; is a widely used marketing gimmick. At no stage in any trials has it showed any activity on eggs or larvae inside the gall but is effective on adult wasps that have emerged (as a lot of chemistry is).
Trees can fruit well from galls due to stress but will suffer from fruit size issues and in the end the tree will be completely unviable, even for a home gardener.