Stewart Addison, Entomolgist - Monsanto, Toowomba discusses the field performance of Bollgard II® during the early/mid season 2005/06.

Stuart, just a comment quickly about the level of uptake of Bollgard II® across the various growing regions?

Well this season there has certainly been a lot more than last year. I think we are looking at roundabout the 80% uptake in total at the moment with Bollgard II.

And heliothis pressure so far. We are hearing about much higher levels of armigera, a lot of moths, armigera moths out there. What are some of the possible causes for the high levels?

Interesting question. We did have a lot of rain prior to the season that may have had some impact but also there is a much bigger mixture of crops out there and the cotton areas this year. It is anyone’s guess really to what the actual cause is but certainly you are right there is a lot more pressure about or has been. We have had quite a lot of instances of 60 – 100 eggs a metre at different times and we are going through another bit of a swell at the moment in numbers as well.

Under the heavy pressure that a lot of these more advanced crops are experiencing at the moment. Certainly, some survivors are being seen so let’s talk through what’s happening in these Bollgard plants in this, particularly in this later stage of growth?

In terms of expression of proteins, still very high expression and you would expect with Bollgard II that’s going to maintain right through to the end of the season anyway. What we are finding at the moment is similar to the same time last year during peak flower intending to get peak flower and heavy egg lay you tend to get a lot more survival in the plants and that’s really mainly so growers will notice if they have a look themselves you can see that there is a lot of grazing of pollen around the anthers and larvae will survive on the pollen and can develop into mediums and larges and it would probably not be that uncommon to find half one grub a metre in peak flower with heavy egg lay. But the main thing is just to watch and see if there is any damage being done because in most places what I am seeing is presence of grubs not the presence of damage. I guess one difference this year than last year its very hot and we are getting quite a lot of physiological drop at the moment and I think that there maybe some concern that some of the drop that people are seeing has been caused by neonates feeding on squares and boll. That’s probably not that likely but having said that it may be that because of the high temperature in some places if the plants are put under stress with that high temperature perhaps they are a bit more susceptible to damage and they may shed a bit earlier but that’s just conjecture. But most places I have seen, most of the drop you are looking at is physiological and I have got no real concerns about damage from heliothis.

Do you think there have been any instances out there where probably a treatment with a spray is justified on some of these survivors or even a spray on heavy eggs?

Quite a few people in some areas have put an application on Bollgard II this year. I think a lot of it is really related to trying to protect the absolute maximum retention in case they can’t get final irrigation on. In which case if your plant is going to cut out earlier, protect what you have got to start off with but we are looking at a lot of retention figures have been sort of 85 – 90% so if you have got water really most people would not be concerned with loosing a bit of that retention or to maximize the final yield and stop the plant just sort of cutting out and growing into a halt. Have put sprays on that are justified? I am sure they have in some instances. It depends on what your criteria is for spraying. If you are trying just to protect a crop from a loss at the end of the season and everything else is equal, you have got your water, your nutrition up to date and everything, then possibly there is not much justification for a lot of the spraying but as I said in those instances where people are not sure about the availability of water later on then in their mind if they want to protect it earlier on I can see the justification for that.

Some of the early spraying that has occurred on the Bollgard crops, have you got any concern about the choice of insecticide that has been made for that role?

I am glad you asked that question because I have really. The three main chemicals that people are using or groups are endosulphan, synthetic pyrethroids and a bit of Affirm has been used as well. Now I know that on your conventional cotton you may be getting 25 grubs a metre and therefore they want to hit those but they are only getting a few grubs they may see in Bollgard II even though they are neonates or very smalls they still may be concerned enough that they may get a bit of drop but to put a cheap synthetic pyrethroid on is always a bit of a concern. I know people are saying that we spend the money on the technology so why spend more on spraying but what I am concerned is if they use sp’s or endosulphan is not so bad but certainly use sp’s you are going to disrupt all those beneficial insects and there is a concern that they maybe some mite or aphid flare-ups as a result of that which could in the end increase the total amount of spraying you are doing on your crop. So they way that I would look at it if at all possible still go for more selective softer option chemicals on your Bollgard II whenever you have got the chance to.

So the grub survival we are seeing in some of these crops this year it is not that different from the situations that we saw last year?

No really it is just the same, nothing has really changed. As I said partly is because of high pressure, high temperatures at the moment but what I would jest a caution, if people see grubs crawling around Bollgard II, firstly look to see they are in the flowers. If you find them in the flowers the chances are you are going to have no loss and is not much risk of having an economic loss. The other place to look is at the edge of the fields. If you have got non BT crops at the edge of the field whether they be refuge crops or sorghum or corn or soybean or whatever you have got at the edge of the field you may find in some instances you are getting some movement from those crops into the Bollgard II. Not this time last year we say that occur, in fact a bit earlier than this and we saw that they could move 40 – 50 metres maximum. So you may find that it is just an edge effect and if it is the thing to do then is to find out is it causing economic damage. If it is, do you spray or not because the changes are they are going to be mediums or larges if they are moving that distance and can you control them. But what we can virtually guarantee is that they will die once they have had a feed they will die, it may take a little bit longer if there large ones coming in from adjacent crops but they will die.

So with a few of these late season survivors that are about, obviously the importance of the refuge and pupae busting and that becomes critical as well doesn’t it?

Yes with 80% uptake of the technology to start off with, you have got less margin for error and if you look at the refuges that we have got at the moment they have been this year there is far more if you like effort being taken to make sure that those refuges are actually working. We have not got other areas of conventional cotton that also acts as a refuge as we had in previous years, 80% of it is Bollgard II. So those refuges have got to work for the whole technology to survive and the audits that are happening now looking at refuges are important there that help growers to make sure that their refuges are working. If they are not working assist them, how can we treat the refuges to make them more affective. Having said that, this year with the extra amount of sun there was earlier on in some of the regions that’s certainly helped I am sure with resistance management that later in the season those crops are gone and they will be relying largely on the refuges that we have planted again.

In summary, you’re quite happy with the feedback you have been getting from all the various regions about the Bollgard performance?

Yes, I think so I don’t think there is any real concerns at all. We have just had some feedback from St. George where some of the pigeon pea there all the buds and the flower buds have been eaten out and chewed away by early heliothis attack but the cotton is still looking pretty good there so they are obviously about doing what they are meant to do which feeding and living in the refuges and hopefully if anything comes out of Bollgard II there is plenty of other moths coming out of refuges to sort them out so we are fairly happy.


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