Cotton Seed Distributors - Web on Wednesday

Dr. Stephen Allen, Senior Research Scientist - Cotton Seed Distributors and CSIRO, releases the 2004 rankings for fusarium and verticillium wilt

Steve, you’ve just completed the disease resistance rankings for this season and that’s been a fairly large job but I was wondering if you could firstly tell us a little bit about how those disease rankings are compiled?

Sure, the rankings are based on field experiments at disease nurseries where the levels of disease are fairly significant. The varieties are planted, the standard Sicot 189 is the standard for all the F.rankings. It’s in every trial, we do a count at the beginning of the season to determine the number of plants that were there at the beginning of the season and then at the end of the season we go in with secateurs and cut off the stems at ground level and look at how many plants or what proportion of the initial plant stand survived right until the of the season. We then basically compare each of the test varieties with survival in the standard and come up with a ranking so that for the standard it will be 100, so Sicot 189 will always be 100. If a variety like Sicot F-1 has an F.rank of 200 it means that twice as many plants survived as compared to the standard.

And in that F.ranking process, for a trial to be valid what are the considerations there?

It’s got to be replicated, plots sizes specified; they have got to be at least 10m plots, it’s got to have an acceptable plant stand and the level of disease has got to be significant. In other words you’ve got to have more than 30% of plants dying from the disease so that we can use the results.

And you ran quite a few trials this year and the majority of those for fusarium are based on the Darling Downs. We might be able to go through some of the F.rank highlights and firstly discuss the three new varieties that being Sicot F-1, which is a new generation fusarium resistant variety, the new Sicot 73 and Sicot 24?

The Sicot F-1 is really exciting. Prior to this season it had an F.rank of 203 based on 8 trials. It’s now based on 15 trial results contributing to the F.rank and it’s 208, so there has been little change in the ranking, which is encouraging but 208 on based on 15 trials. That’s not using some of the trial results where we saw exceptional results, I mean we had one trial near Dalby where there was only 10% survival and the Sicot 189 compared to 66% survival in the Sicot F1 at that site. If we’d used that result only it would have given us a ranking of 640. We didn’t use those in calculating our 208 average F.rank.

Certainly a distinct improvement and the commercial variety with certainly the highest F.rank is that new variety. What about the new Sicot 73?

Sicot 73 we got less trial results, we only had three trial results basically Sicot 73 is coming in at 108 based on the three trials, so it’s not bad. You’d have to say it’s as good as 189 but only with three results so far but they were fairly consistent results at the three sits we had this year.

One of the other concerns the industry has had has being more in the Dryland varieties with trying to shift the F.rank up in those varieties despite the fact that we haven’t really seen Fusarium as a major disease for Dryland; we do now have a distinctly adaptable dryland variety Siokra 24. How does it stack up in terms of its F. rank?

Again a new variety so we only have two results but it’s got an F.rank base don those two trial results of 90, which is again getting close to the 189 and simply better than the Dryland alternatives that have been available in the past.

A lot of growers will be interested in some of the new Roundup Ready® varieties that are available this season and I guess a key one for many growers will be the new Sicot 289RR that’s performed very well in terms of yield but how has it performed in terms of F. rank?

Again not a lot of trial results. We got five trials where we had 289RR in the trial and its average F.rank based on those five trials is currently sitting at 104, which is not bad.

And the other new variety being Sicot 60RR?

Coming in at 91 based on three trials. Again we can’t emphasize too much the importance of the number in brackets, I mean three trials and five trails are certainly better than one but not as good as fifteen or twenty.

Steve could you just run through, there’s quite a few of them, the F.ranks for the new Bollgard® II lines?

Sure well I guess the one that people have experienced with so far is Sicot 14B, which will continue to be available. It’s sitting at 145 on 15 trials. That has changed from 141 based on 6 trials last season. The newer versions, the Sicot 80B only one trial but an F.rank of 137, the Sicot 289 Bollgard® six trials so we are getting up there with an F.rank of 124, moving down to the 40B, which is 107 based on four trials, the Siokra V18B, an okra leaf Bollgard® II, 101 based on seven trials so that’s getting up there and then back to 12B and 13B, which were less resistant varieties in the previous season.

Going onto the stacked varieties now, maybe you could just run through the F.ranks of those?

The stacked varieties, again many of them we only have got one or two trial results but they are starting at the higher level. The Sicot 71BR coming in at 139 based on two trials, the Sicala 40BR 127 based on four trials, the Sicala 60BR 117 based on three trials, the Sicot 289BR 107 based on six trials so we are getting a few trials there, and dropping down to the only one that actually comes under 100 is the Sicala V-3BR coming in at 83 based on seven trials. Apart from that one all the rest are 100 or better than 100, which is encouraging. The breeders are doing a good job.
We’ve got some pretty good results there in terms of F.ranks, we’ve got a range of varieties there now that with F.ranks in whatever category growers want to choose to grow above 100. The other disease that comes to mind maybe make some comments about Verticillium, it’s still a significant disease in many parts of Australia, just in regard to anything significant with any of the Bollgard® II or Roundup Readys or new conventionals?

The verticillium ranking is coming along probably not as quickly as the F.ranking, we always don’t find as many sites with high levels of verticillium but certainly everything we have tried so far and again reminding you that this is based on only one or two trials and in particular with the newer varieties. Everything is comparable to Sicala V-2 or better with the exception of Sicot 289RR, which has come in based on the one trial only has come in as 61, which is low compared to all the rest of them but you might remember that is only based on one trial so it’ll be interesting to see whether that remains at that level after we do a couple more trials.

Steve the other thing is that all of these results will be available, they’ll all be sent out the growers but as well as that we’ll be posting the full data set on the web from the CSD site and very soon anyone can check on those figures.

That’s right. Just go to the CSD website, click on the variety and go to the full trial details. That’ll give you the year of the trial, what sort of trial, the level of disease in the standard, the average F.rank, it highlights the trials done independently by QDPI. The other thing it’s got there which is of value is it’s got a standard error calculated for each of the F.ranks and that’s an indication of how variable the results are, so for instance if you have a variety with a ranking of 100 and a standard error of 10 it means that 95% of the time the results will vary between 90 and 110. If you’ve got a variety with a rank of 100 and a standard error of 80 it means that 95% of the time it varies between 20 and 180 which that way indicated how stable the results are and it’s probably a good aid to interpreting the results.

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