Volume 7 Issue 2
Tim Miller, Weed Scientist
WSU Mount Vernon NWREC
* Since this is a new herbicide registration in the US, it is likely that other nations may not yet have a Minimum Residue Level (MRL) set for Alion in caneberries or blueberries. If you are growing berries for international export, you will want to be sure of the status of the indaziflam MRL in the destination country before applying this product to your fields.
Raspberry and blueberry growers have a new option available for late-dormancy weed control: Alion herbicide. Bayer Crop Science issued their new supplemental label for cane and bush berries last October (CLICK HERE FOR LABEL); if you grow coffee or hops, this label will also be appropriate for you.
While new to berry growers, Alion has been registered in a number of tree fruit and nut crops for several years. The active ingredient (indaziflam) is also registered for roadside use (Esplanade) and for certain horticultural situations (Marengo and Specticle). Consequently, the weed control spectrum for this herbicide is well known, as is the persistence of the product in a number of situations. Alion definitely has a long soil residual! Its half-life generally exceeds 150 days, so dormant-season applications should last well into summer.
The mode of action of Alion is to inhibit cellulose biosynthesis. Cellulose is a chain of glucose (a simple 6-carbon sugar) molecules strung together. All plants manufacture cellulose to use primarily for cell wall construction. If a susceptible plant is treated with Alion, that plant can’t make cellulose, so that plant can’t form cell walls, so that plant can’t grow, and eventually that plant dies. (Plant physiology tidbit: starch is also formed from a chain of glucose molecules. In starch, the glucose molecules are connected by an alpha-linkage. Animals can easily break this linkage in starch they have eaten, releasing free glucose which is used for energy. This release of glucose is why diabetics need to be careful with eating starchy foods. Conversely, cellulose is made from beta-linked glucose which animals can’t break down during digestion. Only certain bacteria and fungi can break beta-linkages, so termites and cows get energy from cellulose through the action of bacteria in their respective guts. People don’t have the bacteria capable of doing the job in our digestive tract, so we don’t get any benefit from eating grass).
Things to know about Alion:
Alion controls exclusively annual weed species, so don’t expect the product to remove the tough perennial weeds commonly found in berry crops (Canada thistle, horsetail, quackgrass, etc.). Broadleaf weed species controlled by Alion include common chickweed, common groundsel, mallow, wild mustard, pigweed, purslane, shepherd’s-purse, annual sowthistle, and willowherb. Additionally, it suppresses wild buckwheat, henbit, wild carrot, and common lambsquarters. Grasses controlled include barnyardgrass, annual bluegrass, crabgrass, and Italian ryegrass. Central Washington growers will be pleased to note that Alion will also control downy brome (cheatgrass) and the foxtails.
* Alion is very much a preemergence herbicide. In fact, if the weed seed has sprouted but not yet emerged from the soil at the time of application, Alion won’t control it. A trial I conducted in established strawberry in 2012 resulted in poor control of several weed species that the herbicide should have controlled. We determined that the reason for this was we had appreciable seed germination occur by the time the herbicide was applied. So if you have emerged weeds where you want to use Alion, you’ll need to kill them with a different herbicide (usually something like paraquat or glyphosate).
* The Alion label specifies that it be used only on caneberry or blueberry plantings that are at least one year old. In addition, the manufacturer stipulates that “exposed roots, open channels, or depressions in the soil” not be treated to avoid direct contact of the herbicide to crop roots.
* Soil type and organic matter content are important considerations with this product. While it doesn’t seem to be susceptible to leaching in typical soil, note that the label does not allow the herbicide to be used on soils with 20% or greater gravel content or on sand. The lower rate of Alion (3.5 fl.oz/broadcast acre) should be used when soil organic matter is less than 1%. The higher rate (up to 5 fl.oz/broadcast acre) can be used if soil organic matter exceeds 1%.
* Alion should be applied from late fall until bud swell in berry crops. Green stems, foliage, and flowers should not be directly treated.
* We don’t really know how Alion applied annually will affect berry crops. I’ve done single-year applications to both raspberry and blueberry and find good selectivity in both crops. I currently have blueberry plots out at five locations in the state that will receive their second Alion application this February (the first was applied in February, 2017). So I should get a good read of this aspect of Alion this year.
* If you are thinking about treating a raspberry field that will be taken out after harvest this year, I’d suggest not doing that. Alion’s long soil residual may cause raspberry plants or plugs transplanted next year to have difficulty in establishing.
On a related note, you may be asking “What about strawberry?” While Alion appears to be fairly selective in strawberry, Bayer has not proceeded with registration for this product. The reason? Most strawberries in the US are produced in an annual system, and Alion has too much carryover potential to use the herbicide in annual cropland. We are hopeful that we can eventually gain registration in perennial strawberry, but that registration has not yet occurred.
Finally, don’t forget that the Pacific Northwest Weed Management Handbook is available to you for tips on other herbicides registered for use in berry crops. You can find it online at https://pnwhandbooks.org/weed/horticultural/small-fruits.