Dr.Stephen Allen, CSD Plant Pathologist, reveals his early findings on the ongoing "Boost" seed treatment trials he has managed for the last three years.

Steve, CSD has been working on a new seed treatment over the last few years. Can you explain what Boost is and how it works?

Boost is a Syngenta product previously known and used in various parts of the world and called Bion or acibenzolar-S-methyl. It basically works by turning on the plants natural defence mechanisms. All plants are resistant, they have natural resistance mechanisms. If you think that there are many thousands of plant pathogens out there, there are only about ten or twenty that are able to attack cotton.

It is completely resistant to all the rest. And the problem with those ten or twenty that can attack cotton is that the pathogen is able to bypass the normal plant defences. So this particular product has no direct activity against the pathogen but it basically works by turning on the plants natural defences and the plant puts up its ‘shield’ and gains some protection to a range of diseases early in the season - and that affect has been shown to last throughout the season and not just for a few weeks after it’s applied.

Steve, there have been different trials using it as a foliar spray, a soil applied drench and then soaking the seed and finally we are looking at using it as a seed dressing. Any comments on whether that affects the way that the product works on the plant?

Initially our experiments were using seed soaking where we took the seed soaked it in a solution of Boost for three hours and then dried it and we realised that it gave us good results but we also realised that that wasn’t going to be very practical for growers. So further work showed that the seed treatment was virtually as effective - in fact in trials where we have had seed soaking and seed treatment there has been no significant difference and seed treatment is a very convenient means - it will be applied to the seed before the farmer gets it. We have done some experiments where we have looked at applying the treatment up to 15 months before planting and with no adverse affects and the benefit are still apparent once the seed is planted.

Specifically what diseases have you been targeting in the trial work?

The majority of the trial work has been aimed at things like Black Root Rot and Fusarium wilt, although we were sort of interested in collecting information on Verticillium and Alternaria as well.

And this year, CSD has set up a large number of larger scale evaluations using Boost, whereabouts are those trials located?

First of all we have got a product evaluation permit from the APVMA that entitles us to do 2,000 hectares or treated hectares of trials in New South Wales and Queensland. It hasn’t been a good year for setting up trials in Queensland but we have extensive trials set up for Black Root Rot in the Namoi and the Gwydir. Fusarium wilt in the Gwydir and the MacIntyre valleys and on the Darling Downs. We have some trials down in the Macquarie and right across that whole area.

I know it is very early days yet but I know you have been spending a bit of time looking at those trials over the last few weeks. Have you got any sort of preliminary comments about how things are working?

Yes, the results are quite encouraging in terms of plant stand we have concluded about 20 trials so far and in most of those there is virtually no difference. In two of them there is 30% and over 40% increase in plant stand which would appear to be significant – not analysed yet - but in one of the sites there was a significantly lower plant stand but it was a site with Fusarium wilt and so the questions is – is Fusarium significant.

In terms of Black Root Rot we have got 13 trials we have got preliminary results from so far and we have basically reduced the blackening of the tap roots by an average of 16% over 13 trials which is good. In three of those trials it was 30 to 36% reduction in blackening of the tap root.

That would be accompanied we expect by better seedling growth and over the next few weeks we will be actually doing dry weights in those trials to monitor improved early season growth. In terms of Fusarium there are only 3 or 4 trials out so far but basically there are two to four times more dead plants in the control plots than there is where we have used the seed treatment. So we are encouraged at this stage but we have got the whole season to go before us yet.

I should point out that you have done quite a few years work on Boost now. Any comments on previous years testing on small scale?

Yes I guess there is - we are going for large scale trials because the results of all our small plot work have been very encouraging and we have seen significant benefits in terms of Black Root Rot and Fusarium control. Having said that it is not the solution to the Black Root Rot and the Fusarium problems - it doesn’t give absolute control - but we see it as giving a significant contribution to control and when combined with time of planting and better varieties and a range of other practices we look at it as being an aid to giving farmers adequate control.

Further Information:
Robert Eveleigh, John Marshall,  Craig McDonald, David Kelly or James Quinn