Carrying out integrated weed management in different orchards has been one of the fundamental challenges of modern agriculture. In this regard, residual herbicides are the perfect tool for proper control.
And it is in this context that Bayer has new products; its Alion 500 SC product, starting this season, has a label extension by SAG for cherry, walnut and hazelnut trees to be used starting in one-year-old orchards, which, in addition to confirming the safety of the products in crops, allows anticipating a fundamental task in orchards, such as weed control.
It is worth remembering that residual herbicides or soil-active herbicides are nowadays a key tool to control weeds from seeds in fruit orchards, vineyards and vineyards. Of course, the effectiveness of the products will depend on the herbicide used, but it is always advisable to use one that keeps the field free of weeds for a long period of time and thus allows the producer to focus on the productive part of the orchard.
Residual herbicides are applied in autumn and winter, when there is more rainfall, so it is essential that they have physicochemical properties that provide safety of use, greater efficiency and do not cause damage to the fruit tree. There are physicochemical parameters of herbicides that allow a comparison between active ingredients and their
phytotoxicity potentials, under the same soil, rainfall and herbicidal efficacy conditions. These are parameters associated with the mobility of the molecule in the soil profile and its persistence.
Solubility and adsorption
The main ones are: Solubility, organic carbon partition coefficient (Koc), half-life (DT50). Solubility together with the Koc of a herbicide are key parameters in determining its leaching potential, or rather its mobility in the soil.
The solubility of a herbicide is the amount of product that enters into aqueous solution. Products that are highly soluble in water are extremely mobile and can be transported in the soil profile by rain and/or irrigation, and can even reach surface or underground bodies of water. Low-solubility herbicides, due to their greater affinity for soil, are safer to use in fruit orchards.
While the Koc of a herbicide indicates the degree of adsorption of the herbicide to the soil, that is, the capacity of the active ingredients to bind to soil colloids. Herbicides with Koc less than 500 mg/g present a high mobility in the profile, with a risk of leaching or reaching the root zone. Herbicides with a higher Koc value will present a higher
soil retention (colloids).
If highly mobile herbicides are used in the soil, there is a risk that they may reach the root system of the plant, which may cause physiological damage and/or residue problems in the fruit, in the case of systemic products.
It is very important to know the parameters that define the mobility of a herbicide molecule in the soil, in order to take into account the measures that must be considered as protection, in terms of the age of the orchard, type of soil and time of use, so as not to be exposed to rain and possible dragging into depth.
DT50 or half-life: It is a parameter that indicates the persistence of the product in the soil and corresponds to the number of days required to reduce the applied dose by half. It is an indicator that allows us to deduce the residual effect or activity of the herbicide over time.
Alion® 500SC
This product has a DT50 of 150 days, after 150 days there is still 50% of the dose of the commercial product applied. It is also characterized by its long residual effect, which is explained thanks to the balanced interaction of the indicated parameters, plus others such as low volatility, stability to photolysis, among others, and the powerful herbicidal activity of the active ingredient Indaziflam.
This is because it is the only residual herbicide on the market that was designed to work residually in the soil of fruit and vine plantations.
Alion® 500SC does not discriminate between mono- or dicotyledonous weeds, resistant or tolerant, annual or perennial from seed. Its active ingredient acts at the most sensitive stage of weeds, at emergence. It acts by inhibiting cellulose synthesis, a key process in the seed germination stage. This mode of action results in the broad spectrum of weed control that the product presents, even intervening with weeds that are very difficult to control for other herbicides.
On the other hand, the product has no post-emergence effect; it is a contact herbicide, which must be applied in a pond mixture with post-emergence herbicides, such as Faena FG. Its safety is concentrated in its physicochemical properties, which have been explained in detail previously, and in its contact mode of action.
Multiyear trials on different species, with applications one year after the orchard was established, have confirmed the selectivity of Alion® 500SC under different soil and rainfall conditions throughout Chile since 2006. Currently, the SAG resolution is expected to extend the application window to cherry, hazelnut and walnut orchards, one year after they were established.
Santa Elena Agricultural Demonstration, cherry orchard planted in 2018. Regina variety over Gisella, in the town of Molina.
The application of Alion® 500SC at 200 cc/ha + Roundup Ultramax 2 Kg/ha with 200 L water/ha was carried out on July 25, 2019.
In sandy loam soil (sand 60%, silt 36% and clay 4%) with 7.4% Organic Matter.
Quantitative evaluation of trunk diameter in plants with and without Alion® 500SC did not present significant differences, under a technical micro-sprinkler irrigation system, confirming the high selectivity of the product.
Bayer's announcement regarding the extension of the label of its Alion 500 SC product for use in 1-year-old orchards, which was previously indicated from the third year, will allow for early weed control, one of the main problems that producers are exposed to in their new plantation projects.
