Plant Science Expert Panel

Leaf

Sense about science is hosting a valuable Q&A between the public and a panel of plant scientists. You can participate

Send questions via our online form, Twitter to @senseaboutsci using #plantsci, or email us at plantsci@senseaboutscience.org.

The linked science panel page is comprised of expert answers attached to the public questions. As you would expect given the makeup of the UK science panel, the quality of the responses is high. I’ve selected one example demonstrating the nuance offered by Professors Jones and Leyser:

“The environment secretary, Liz Truss, has said that US farmers growing GM crops use less water and less pesticide. Is she right to say this?”
08/01/2015

Prof Jonathan Jones:
GM is a method that can be used to confer many different and useful traits. Liz Truss is right to say GM crops can reduce the environmental impact of agriculture. In the US, Bt maize and Bt cotton require less insecticide to control insect pests. Glyphosate (Roundup) is a less damaging herbicide than the herbicides it replaced. Unfortunately, like antibiotics, reliance on one compound (glyphosate) has selected herbicide-resistant weeds in the US, reducing glyphosate effectiveness for weed control. Another GM trait in maize has been used to elevate tolerance of drought stress. For the UK, blight resistant potatoes will require less fungicide applications, and there are many other potential nutritional and agronomic benefits that could be conferred using the GM method.

Prof Ottoline Leyser:
Farming practices associated with each GM crop differ, depending on the specific characteristic that has been introduced. It is therefore not meaningful to state that growing GM crops results in less water and pesticide use, because it depends entirely on which GM crop you are talking about and what the normal practices are for the equivalent non-GM variety. For example, there is very good evidence that the use of GM cotton engineered to resist insect attack has reduced the use of insecticides in cotton production compared to previous practice. However, the use of GM technology to increase vitamin A production in rice does not affect how much pesticide is used.

One type of crop where there has been a particularly vigorous debate about the environmental impacts is herbicide-tolerant crops. There is no doubt that the widespread planting of herbicide-tolerant crops has led to an increase in the use of the specific herbicides tolerated by these crop varieties. Some argue that this has reduced the use of alternative, more environmentally-damaging herbicides. Others point to the negative effects on insect biodiversity caused by the reduction in weeds associated with more effective weed management. Others still highlight the emergence of weeds resistant to herbicides. These debates are important, but they have nothing to do with GM. While many herbicide-tolerant crops have been produced using GM methods, others have been produced using conventional methods, and all the arguments are about herbicides and their use, not about GM. Just as it is inaccurate to say that GM crops reduce pesticides, it is equally inaccurate to say that they cause superweeds.

We need to be able to choose the best solutions to each challenge facing the food supply chain. In some cases this will include a particular GM crop, but in many cases it will not.