London (13.6.09) – It is self-evident (or ought to be) that, for them to work satisfactorily, all technologies need to be managed properly and with foresight as to the consequences of procedures. It is not enough to have airliners that fly efficiently and safely with airports for them to use; there must also be a system of air traffic control to make sure they don’t bump into one another, a network of fuel deliveries so they can fill their tanks at airports and another network to sell tickets to passengers. Just having the aircraft and the airports is not enough.

So it is with agricultural technologies, but differently. Any intervention into a biological system – such as the cultivation of a patch of ground – inevitably has consequences. All biological systems are interactive: prod them and they will react in some way or another. Nor are they “in equilibrium” but rather in an active state of “equilibration”, each living (and some non-living) component endlessly responding to changes in its local environment, whatever they might be.

As biotechnology in agriculture arose rapidly in an environment of agricultural skills it was possible and reasonable to put in place management techniques appropriate for each development to ensure as far as possible that each outcome would be as favourable as possible. Nobody, of course, could guarantee success under all circumstances: there may be factors coming into play which were not or could not have been foreseen so continual alertness and management is essential. This is one of the great strengths of the human intellect: an ability to understand, analyse and correct activities, and to adjust practices in the light of experience.

There have recently been some good examples. With the introduction of Bt-cotton to areas of the United States plagued by cotton boll weevils there was rapid and enthusiastic uptake of the new strains which saved time, effort and money by less spraying, a direct benefit to cotton growers. There was a cost, however: the seeds are more expensive so individual farmers had to balance that additional cost against the benefit of not having to suffer the damage of insect attack (1).

But over time, and in some places, that economic balance has changed. In Alabama, some growers are leaving the Bt varieties and returning to “conventional” strains. One farmer from the centre of the state said: “Growing conventional cotton was a matter of economics for us. We have dryland cotton and problems with reniform nematodes. We just didn’t have the yield that would allow for the technology fee. Then, when boll weevil eradication came along, we no longer had the need for the Bt.” Thus, when after several years the insect pressure falls because of Bt-cotton, some farmers can fairly safely return to the conventional crop. How safely depends on the proportion who revert: the more who do so, the more rapidly the boll weevils will return. After a time there will no doubt be a swing back to using Bt-cotton.

Something similar is happening with herbicide tolerance based on glyphosate; that same farmer commented: “Now that we’re seeing resistant weeds, the glyphosate technology has diminished in terms of value.” So farmers adapt their technology to changing circumstances, using variety of herbicides to meet their need. And the plant breeders, knowing from the start that this was a possible consequence depending on how herbicide tolerance was used, have developed new varieties with multiple resistances making the advent of the resistant weeds less likely (2). Such new soybeans are now being extensively planted (3).

Farmers, of course, use their own experience and the availability of products on the market to optimise the performance of their own crops. Also in Alabama, a number of different herbicide control systems are in use; as producers in central Alabama have continued or begun to grow conventional cotton, the state’s Extension system have conducted trials to compare these systems with the Roundup Ready system (4).

Sources:

1. Paul L. Hollis (9.6.09). Alabama growers stick with conventional cotton. Southeast Farm Press (http://southeastfarmpress.com/cotton/cotton-production-0609/index.html)

2. Genuity™ Roundup Ready 2 Yield™ soybeans. Genuity (2009) (http://www.genuity.com/Traits/Soybean/Genuity-Roundup-Ready-2-Yield.aspx)

3. Genuity™ Roundup Ready 2 Yield™ soybeans planted on 1.5 million acres this season. Seed Today (26.5.09) (http://www.seedtoday.com/articles/Genuity_trade__Roundup_Ready_2_Yield_trade__Soybeans_Planted_on_1_5_Million_Acres_This_Season-76232.html)

4. Paul L. Hollis (10.6.09). Cotton weed control systems compared. Southeast Farm Press (http://southeastfarmpress.com/cotton/conventional-cotton-0610/)

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