Tag Archives: herbicide

Ethephon, the ‘good guy’ organophosphate?

14 Mar
Ball-and-stick model of the ethephon molecule,...

Ball-and-stick model of the ethephon molecule, the most widely used plant growth regulator. Colour code (click to show) : Black: Carbon, C : White: Hydrogen, H : Red: Oxygen, O : Orange: Phosphorus, P : Green: Chlorine, Cl (Photo credit: Wikipedia)

Have you ever tried putting an unripe pear in a paper bag with a ripe banana to ripen the pear more quickly? Go ahead! It works. The reason this works is because many ripe fruits give off ethylene, a gaseous growth hormone, when they are ripe, and ethylene triggers the generation of more ethylene, in a cascading, snowball effect within these ‘climacteric’ fruits. Ethylene also triggers stems and leaves to senesce, or turn yellow and mobilize their valuable photosynthesis machinery to other parts of the plant. In the original example, if you put a head of broccoli in the paper bag with the ripe banana, the broccoli will yellow and then brown. Pest managers have learned that you can use this hormone to good advantage in an integrated pest management plan by hastening the ripening of fruits to avoid late-season pest pressures such as walnut husk fly in walnuts. But how can you target the application of a gas like ethylene to the fruits of a tree in an orchard at high enough concentrations to ripen the husk (fruit) of the walnut tree? The answer might surprise you: spray an organophosphate pesticide such as ethephon that breaks down into ethylene and phosphonic acid. This stuff is now only registered in the USA as a plant growth hormone, but in fact it was originally registered in the 1970’s as a pesticide and has pesticidal properties, acting upon the nervous systems of insects, crustaceans and humans. It is a lousy pesticide, since it is not very toxic to insects and breaks down quickly in the environment, so nobody uses it as a pesticide on purpose any more. Instead, it is used exclusively as a growth regulator. http://1.usa.gov/16w8BO7

Avoidance by changing the timing of harvest is a wonderful strategy for preventing the need for ‘real’ pesticides which have serious insecticidal properties in the late season. I think it is important, however, to be aware that this stuff is actually an organophosphate pesticide as well, and to take proper precautions when applying and storing it, just as you would if you were spraying diazinon or chlorpyrifos or any other major organophosphate pesticide, which everyone knows are neurotoxins by means of inhibiting the enzyme cholinesterase in the brain. We can toy with the idea that we are using a safer material, but safer is a relative term.
Also, please note that ethephon acts upon plants as a growth regulator and upon insects and mammals as a neurotoxin, so let that be a lesson to ya not to assume, as I did, that plant growth regulators are as safe as water for human handling and for beneficial insects.
In my amateur opinion, then, ethephon is an undercover organophosphate playing the ‘good guy’ in today’s orchard crops because of the small concentrations and low toxicities applied and because these applications allow farmers to avoid rather than treat late-season pests through early ripening, but it is important to remember that this stuff is still a neurotoxin and to take proper precautions when handling it.

Ploughshares into spray nozzles–the California Tour

6 Sep
English: Wild elephants in Munnar, Kerala

English: Wild elephants in Munnar, Kerala (Photo credit: Wikipedia)

How will farmers feed 9 billion people by the close of this century? That is the question posed to six renowned leaders in the field of conservation farming during the Conservation Ag Systems Innovation conference tour (CASI)
On August 28th, 29th and 30th,
Jeff Mitchell, University of California Cooperative Extension Specialist,  gathered together some of the world’s great visionaries to sell conservation farming practices to California farmers, students, and agency staffpeople. Conservation farming, a term used to refer to no-till, minimum tillage and controlled traffic farming practices, is popular in the midwestern US because it saves water and cuts fuel costs while preserving soil organic matter, which has many benefits to soil fertility. No-till is also popular in South America, particularly in Brazil, while controlled traffic farming (with conventional tillage) is practiced in Tasmania, an island off the coast of Australia, for the purpose of reducing soil compaction on the cropped rows while improving traction on the trafficked rows.

Don Reicosky from Morris, MN, a retired USDA ARS employee, explained the nuts and bolts of tillage and likened it to natural disasters for soil microorganisms. The best tillage is no-till, he explained.
Rolf Derpsch from Paraguay, who has worked in Brasil, Argentina, Somalia and Germany, explained why conservation tillage not only saves water but also reduces the need for fertilizer because soil microbes and organic matter act as a slow release fertilizer, protecting ground and surface water from contamination. He said that early adoption of no-till in South America was easier to support than here in the US because there was no initial attachment to what we call conventional tillage, and the yield increases with less gas and less fertilizer inspired the spread of conservation farming there.

Clay Mitchell from Geneseo, IA grows corn and soybeans alternating in a north-south direction to maximize profitability based on market prices for those two commodities, but that is not all. This farmer has combined controlled traffic farming with satellite GPS (Global Positioning System) technology, and an awe inspiring data collection protocol which allows him to micromanage the fertilizer application based on things like prior yield in a particluar square foot of field. Tillage has long been considered the primary way to get rid of weeds and make the fertilizer applications and rooting depth more uniform. With no-till, surface application of soil ammendments like lime (calcium or calcium-magnesium carbonates) could be inconsistent and will only reach a depth of a few centimeters during a growing season, so Mr. C. Mitchell advises crop rotations rather than tillage to incorporate surface applied lime at depth, and he relies on satellites to position his fertilizers exactly where they are most needed rather than tilling for greater uniformity. This is a real engineering problem solving strategy, but weed control

Jerry Hatfield spoke about what the EPA and the California Air Quality Control Board want from soil, and how much more food we will need to produce on the same land. These two ideas do not conflict–by keeping more carbon on the ground, soil water holding capacity goes up, meaning that less irrigation water is needed and droughts are less severe. Water use efficiency increases as does productivity per unit fertilizer, giving us some hope for the future, when worldwide land area will decrease while demand will be as high in the next 10 years as in the previous 100 years.

John McPhee of Burney, Tasmania explained how GPS technology can aid in controlled traffic farming which reduces erosion and compaction, improving drainage and allowing cultivation and planting sooner after rain events. He said that tillage was an integral part of his operation and it was not popular to consider no-till systems in Tasmania. He likened the soil microbes to an elephant per acre, and the residue left in the field as food for the elephant -FEED the Elephant!

I would like to suggest that there was another elephant in that room. Herbicides. There is no such thing as organic no-till. Tillage is a wonderful alternative to herbicides and with all the hype about overuse of Roundup and other easily available potent herbicides, which results in herbicide resistance in common weed species such as Palmer Amaranth. Mr. Clay Mitchell of Iowa explained that he rotated his herbicides by rotating his GMO corn and soybeans from Roundup Ready varieties to Liberty Link varieties (the first can tolerate lots of the herbicide Roundup, or Glyphosate, and the second can handle a lot of Glufosinate, an herbicide with a different mode of action. Rotating modes of action is smart to prevent resistance in weed species, but mechanical control is the only option for organic growers, so if we stop plowing, we protect the environemnt from carbon dioxide and particulate matter but this system depends on constant innovation of herbicide chemistries to keep up with herbicide resistance, and constant new developments in the world of GMO’s to allow excessive herbicide applications. The herbicide question looms large in my mind, particularly for the developing world, where transportation infrastructure increases the cost of everything from fertilizer to herbicide to parts for fancy GPS directed no-till equipment. So feed the soil microbial elephant, and give that herbicide elephant a few peanuts too, while you’re at it–the future of humanity and food security depend on it!

Well-Water Consumption and Parkinson’s Disease in Rural California.

4 Mar

Why are there no pesticide well water standards? I have spoken to landowners who would rather not have their well water tested for fear that their property values will go down. Aquifers are connected.

Gatto NM, Cockburn M, Bronstein J, Manthripragada AD, Ritz B, 2009 Well-Water Consumption and Parkinson’s Disease in Rural California. Environ Health Perspect 117(12): doi:10.1289/ehp.0900852

Why it is important to read the herbicide label for recommended rate and ‘INACTIVE’ ingredients . . .

29 Feb

How many people read the label before going out and spraying the weeds in their back yards? Home owners are renowned for believing that if some is good, more must be better. Do they use protective gear like long sleeves? “In the summer? Are you kidding? No way!” What about the inactive ingredients? Obviously if they are inactive ingredients they must be less toxic than the active ones, right? WRONG!
A few weeks ago in my Weed Science course at UC Davis (a fabulous class, I recommend it highly), I learned that much suffering could have been averted if only Agent Orange were made more carefully, without as much Dioxin (a very hazardous contaminant that was not needed for defoliation, but was sprayed right along with the defoliants during the Vietnam War).
In a 5 part series, the Chicago Tribune Watchdog column story goes into some depth and interviews victims of this manufacturing oversight.

Check it out. Why is this not taught in history class? We have enough chemistry to understand this in high school. Please give us your 2 cents on this one!!