Better, worse or the same?

Now we are into the 2012 Conker Tree Science season, it is interesting to wonder whether this year is better or worse than previous years in terms of the level of damage caused by the moth.

One person from south Wales emailed to say that of the two trees she had been watching: 

"Both trees were very badly infected early on in the season this year with leaves shrivelling and dying following the harsh winds and weather.  However I think this has actually benefitted the trees as they have subsequently produced new leaves which, at the moment, show no signs of infection.  The trees had enough time to produce new leaves which seem to be outside the normal cycle of the moth.

   I think leaf litter may explain some of the infection but certainly is only part of the story. The weather is certainly a major factor.  2 years ago when we had quite a dry year the badly infected tree did much better and actually produced some conkers which it hasn't for a while."

I'm sure that weather does have a role in influencing moth numbers where the moths have been for several years - but what type of weather affects the moths? Is winter or spring weather more important?

Another person, from Leicestershire, also emailed to comment:

"This is to tell you that hereabouts infestation is vastly reduced from previous years. No trees are predominantly brown from a distance and on many that were heavily infested last year it is difficult to find any mines."

How is it looking in your area? Are the trees faring better or worse than last year? Feel free to add your comments below.

Welcome to Conker Tree Science 2012

Welcome to Conker Tree Science 2012!

What can you do now?

1.  Take part in Mission: pest controllers (http://www.conkertreescience.org.uk/pestcontrolmission.html). You can collect infected leaves for this mission from 3-8 July inclusive.  Bag up the leaves so the tiny insects can't escape and after 2 weeks see what has emerged from the leaf.  Help us discover how many alien moths are being attacked by pest controlling wasps. Submit your results from 18-22 July inclusive.

2.  Take part in the Mission: alien moth survey (http://www.conkertreescience.org.uk/surveymission.html). Look out for conker trees, see if they show leaf mine damage and report your results via the website http://www.conkertreescience.org.uk/surveysubmitresults.html or the Leafwatch smartphone app (http://leafwatch.naturelocator.org/). Will the moth be confirmed further north than Newcastle this year? Will this year be worse than last year for the horse-chestnut trees?

3. Visit the project blog (http://conkertreescience.blogspot.co.uk) for all the up-to-date news. There you can see a summary of the results from last year. We’ll also be keeping this up-to-date with answers to your questions.

4. Get a sneak preview (http://conkertreescience.blogspot.co.uk/2012/07/natural-pest-contollers-not-just-wasps.html) of the new mission that we will be launching this in August.

We look forward to receiving your results to help us understand more about what is happening to our conker trees.

Best wishes

Michael Pocock & Darren Evans

P.S. Please forward this email to anyone who may want to know what is happening to conker trees.

What about the leaf litter?

From time to time we've had queries about leaf litter under horse chestnut trees, specifically whether it is a problem and, if so, what should be done about it.

It was for this reason that we invited people to record the vegetation under their trees in 2011 when recording the amount of damage that the moths had done. The final analysis is close to completion, but a look at the preliminary results suggests that:

The presence of mown lawn under horse chestnut trees, which was taken as a measure that leaf litter would not have been present over the winter*, is related to a reduced amount of damage recorded for any particular location and time.

In other words - the data people collected strongly suggests that clearing leaf litter is worth it to reduce damage to your tree!

2 trees just 50m apart, photographed on 2nd July. The one on the left had leaf litter under it during the winter. The one on the right did not have leaf litter under it during the winter. Of course, the presence of leaf litter may not be the only factor affecting how much damage there is from the horse-chestnut leaf miner, but it could have been important.

(* Of course, some trees with other types under the tree canopy could have had their leaf litter cleared away, but our observations suggest that this would be a minority. If we had been able to take that into account that would have strengthened our results. So, why did we not directly ask people whether there had been leaf litter under the tree the previous winter, or whether it had been cleared away? The answer is that we wanted this project to be open to anyone - so they could answer all the questions even if passing a tree they had never seen before.)

Natural pest contollers - not just wasps?

In Conker Tree Science we've been focussing on the tiny wasps that could act as natural pest controllers for the horse-chestnut leaf-miner. It's an incredible demonstration of the way in which we can rely on insects that are quite so small.

However, evidence is emerging (partly thanks to those who submitted photos via the Leafwatch app) that there may be bigger, fluffier pest controllers around! It seems that birds (probably blue tits and great tits) are preying upon the pupae of the moth, by ripping open the leaf mines.

Here you can see where the bird (probably a blue tit) has ripped open the leaf to prey upon the leaf-miner pupa.

We thought this was worthy of investigation, so we are working on a new mission: bird attacks for people to take part in during August and September. Just like the other two missions, this is a way for anyone to get involved in genuine scientific research. Register to receive updates about this mission and how to take part.

More apps for invasives

If you like the idea of recording invasive wildlife with your smartphone, then you'll probably like the new Plant Tracker app.

The idea developed from the success of the Conker Tree Science Leafwatch app. The Environment Agency saw how well it worked and realised that something similar would be ideal for tracking invasive plants. For some species, in some rivers, this would be especially important because it could allow Environment Agency staff to go and control the plants, so stopping them spreading and causing a problem.

The app is designed for people to report the presence of three invasive plants:

• Himalayan balsam 
• Japanese knotweed 
• floating pennywort 

Although the app is currently focussed on the Midlands region, we'd welcome records from anywhere to support its roll-out to Environment Agency regions across the country.

As the press release states, This is the latest app that has come from IT Services R&D at the University of Bristol. It was funded by the Environment Agency and University of Bristol, in collaboration with the Centre for Ecology & Hydrology.