Rhizoctonia, tell us as you are walking through a paddock what would you be looking
for then?
Primarily you are looking for the distinct patches as we can see in the field
in here
but it depends when the infection occurs. So if you get
early infection you do get the distinct patches,
that is, its affecting the seminal roots.
Whereas if you get later infection the crown roots
you'll often get the waviness and we've got some waviness
here too. It might be potentially both have occurred here.
Infection can occur all the way through the growing season,
it's not on a particular time and that's what makes it very difficult to control.
And a serious impact no doubt on the production in the paddock. Yeah it's
estimated to cost the grower wheat and barley annually
$27 million dollars in Western Australia.
So it's quite a big problem. It is widespread, we've seen it all the way from
Salmon Gums
up to the northern regions
so it’s a wide spread issue. And digging under the ground no doubt is a really
important thing in the root condition like this?
It's really important to look below the ground
at the roots. Above the ground it could be nematodes
it could be rhizoctonia. It's not often easy to distinguish
between the two and you can actually get both
co-occurring together. So when you dig up the roots
then you get a distinct symptomology
for rhizoctonia. You get spear tipping and we can see it on these
particular plants here there's distinct spear tipping on the crown roots
and that would be what is rhizoctonia.
With any root pathogen it's really very difficult to do anything at that time
so you need to get the correct
diagnosis so that you can
understand what the issue is and then you can do something about it
in the next season. For rhizoctonia
it's very tricky because there are so many is susceptible hosts
So all the cereals are susceptible, barley is the most susceptible of all,
canola, even the weeds are very susceptible too so if you've got
a lot of weeds in your paddock especially over summer
it can keep that inoculum increasing
over that time which then when you put your crop in
you have a bigger problem potentially so even weeds are
potential hosts as well
At the moment what we have
are a number of seed treatments and they do offer some protection.
In our trials on average about 5 per cent
it can be either way. We had I think up to 15 per cent
control but we're also working on some
new potential control options that hopefully will be released in the next year or two
and they'll offer up to 15-20 per cent
control. As I said in terms of rotation its it's very hard, although we did find
for canola that the inoculum levels do seem to drop
down a bit but if you've got a paddock with really high
inoculum then it may not actually
solve the problem for you and as I said
canola is susceptible anyway. And what are the key messages?
Key messages are, make sure you have the diagnosis correct,
look at the roots and
identify what the primary problem is
and also send away your samples to get that
diagnosis correct.