What's New in Biological Control of Weeds? Issue 70
In this issue
![Sawfly laying eggs Sawfly (<em>Dolerus germanicus</em>) laying eggs on horsetail in containment.](https://oldwww.landcareresearch.co.nz/__data/assets/image/0007/80971/varieties/thumb200.jpg)
Field Horsetail Project Forges Ahead
Because field horsetails has a deep root system, it is difficult to find chemicals that penetrate deep enough into the roots to be effective. As a result, field horsetail is not able to be controlled adequately and biocontrol might be the only hope of managing the plant and preventing further spread.
![Moth plant rust Moth plant rust with hyperparasite (<em>Cladosporium</em>) inset. Image - Freda Anderson](https://oldwww.landcareresearch.co.nz/__data/assets/image/0008/80972/varieties/thumb200.jpg)
Promising Pathogen for Cruel Climber
The invasive climber Araujia hortorum is pollinated by insects, especially moths, and so is usually referred to as moth plant in New Zealand. However, a secretion inside the flowers sometimes traps and kills these winged visitors, so it is also known as cruel plant.
![Black floral smut Black floral smut found in Chile. Image - Hernan Norambuena](https://oldwww.landcareresearch.co.nz/__data/assets/image/0009/80973/varieties/thumb200.jpg)
Pampas proves to be a difficult target
After three years of searching for potential biocontrol agents pampas has indeed proven to be a difficult target, but not always for the reasons we expected!
![Buddleia leaf weevil Buddleia leaf weevil. Image - Scion](https://oldwww.landcareresearch.co.nz/__data/assets/image/0005/80969/varieties/thumb200.jpg)
How Many Replicates Are Enough?
An essential step in the introduction of a new biocontrol agent is an assessment of the risk it poses to non-target species. Thoughtful experimental design and statistical analyses are needed to ensure valid results are produced and that their meaning can be interpreted correctly so that suitable agents are not rejected unnecessarily or unsuitable agents released.
![Green thistle beetle Green thistle beetle adult. Image - Jesse Bythell](https://oldwww.landcareresearch.co.nz/__data/assets/image/0011/80975/varieties/thumb200.jpg)
Summer Activities
Summer is a busy time in the world of biocontrol. Some activities you may need to schedule over the next few months are listed below.
![graph adventive herbivores The number of adventive herbivores in New Zealand, and those that feed, or do not feed, on New Zealand indigenous (native) plants.](https://oldwww.landcareresearch.co.nz/__data/assets/image/0003/80976/varieties/thumb200.jpg)
Which Insects Pose the Greatest Risks?
Our expertise in determining which insects attack which plants has recently been put to a slightly different use, i.e. helping to predict risks to native plants.