Key learning outcomes
- Develop an understanding of the non-chemical methods of weed control that can be utilised
- Be able to describe the different types of mechanical weed control
- Have familiarity with Harvest Weed Seed Control (HWSC) methods for reducing seed return between crops
- Develop understanding of newly developed tools including electric weeders, foam weeding and thermal weed control
Non-chemical methods of weed management includes a diverse range of tools that includes mechanical weeders, electric weeders, seed mills and chaff carts. This module will introduce all of these techniques, with greater detail supplied those that are currently viable for growers. The interaction between these tools and the weeds to be controlled strongly determines eventual success so you will be given an introduction to how this manifests itself on farm.
Physical methods of weed control
This is a presentation developed by Philippe Delval, ACTA, France. The video is about 12 minutes long. Additional notes, comments and links to additional content are given below the presentation.
Music by Bensound.com
Comments, notes and resources referenced in the video
Disinfecting and cleaning work tools: soil, pruning, harvesting, transport
Mechanical, manual or motorized tools used in agricultural work can be vectors for the dissemination of harmful organisms, especially pathogens, contained in plant residues or on soil present on the surface of these tools.
IWMTOOL: One factsheet is dedicated to describing weed seed collection and destruction
Collecting and destroying weed seeds during harvest is a strategy originally developed in Australia, now being studied elsewhere on the world.
IWMGAME [arable crops]: One card is representive of this measure. It hasve preventative effects limiting the seeds you will transfer from one field to another one. You can play it during the intercropping period and this method have no side effects. This method is not effective on perennial weeds.
Limiting the seed stock by collecting chaff
The installation of a chaff collector at the rear of the combine harvester helps reduce soiling of fields by exporting weed seeds harvested at the same time as cultivation (reduction of soil seed stock).
Organizing the harvesting operation to prevent the spread of weeds
A right way to control the spread of pests from field to field is to manage harvests to prevent the material from carrying a biological form of the pest. It is therefore essential to know the distribution of weeds between and within the fields.
IWMGAME [arable crops]: One card represents agronomic measures at harvest period. It mainly has preventative effects, limiting summer grasses seed stocks. You can play it at the last stage period. These methods have limited side effects on soil quality due to the equipment.
Topping off to prevent mature weed seeds from returning to the ground
In the practice of topping, the height difference between the crop and the weeds is exploited to cut the inflorescences of the weed, which prevents the production of seeds and propagation in the crop.
IWMGAME [arable and perennial crops]: Two cards represent agronomic measures during the cropping period. It has mainly preventative effects, preventing the production of weeds seeds. You can play these cards at different periods, depending on the method. These methods have neutral side effects.
IWMTOOL: One factsheet is dedicated to describing weed management using mowing
Weed population dynamics are affected by post-harvest treatments in the field, such as mowing weed stubbles. This prevents further development of the weed plants, the seeds and vegetative propagation in the soil while nutrients and water between weeds and crops are balanced due to the short weed canopy height.
|9||In IWM, like IPM, alternative measures are to be favored|
Control pests manually or using manual tools
In some cases, it is possible to control pests and diseases by intervening manually on the crop: manual weeding which can only be localized or concern occasionally problematic plants (invasive, perennial).
IWMTOOL: One factsheet describes hand weeding
The most ancient weed control method, hand weeding, is a method that minimizes the build-up of weed populations that escape all other weed control efforts by removing them directly by hand. Weeds are either pulled out of the ground or controlled by chipping or digging them out using hand-held tools.
IWMGAME [arable & perennial crops]: One card represents this measure. It has only curative effects eliminating weeds and only concerns invasive and perennial weeds. You can play it at any period and this method has no side effects.
Practicing mechanical weeding of annual crops over the whole surface
Mechanical weed control in the open can be implemented in annual crops pre-emergence or just after emergence. It can also be used in perennial crops to manage inter-rows. In general, it targets weeds at early stages of development, and will be more effective on dicotyledons than on grasses.
Practicing mechanical weeding on the inter-row in annual crops
The farmer wishing to control the weed flora of a crop post-emergence can intervene in the inter-rows by using mechanical weeding tools: a cultivator mainly but also a weeder.
Practicing mechanical weeding on the row in annual crops
The farmer wishing to control the weed flora of a croppost-emergence can intervene in the rows, by using mechanical weeding tools such as finger cultivators or reels. These flexible rubber fingers penetrate a few centimeters below the soil surface allowing weeds to be pulled out of the row at early growth stages.
Practicing mixed chemical / mechanical weeding in annual crops
Mixed weed control consists of implementing chemical weeding on the row coupled with mechanical weeding in the inter-row of row crops. Localized treatments (on the row or at the level of outbreaks) make it possible to reduce the quantities of phytosanitary products applied per hectare.
IWMTOOL: One factsheet is dedicated to describing mechanical weeding
Mechanical weed control is done with machinery that cuts, pulls, uproots or buries weeds. Mechanical weed control is a means of reducing the impact of weeds on crop growth, preventing seedlings from reaching maturity and reducing the buildup of weed seed- and bud banks. Available tools are: harrow, hoe, ridger, finger weeder and torsion weeder
IWMGAME [arable crops]: Several cards represent mechanical weeding. It has only curative effects, eliminating weeds and only manages annual weeds. You can play it during cropping period (mechanical weeding). Negative or positive side effects depending on the method. Combined weed control use chemical control on the row and mechanical in the inter-row.
IWMPRAISE Inspiration Sheet: Three IS describe mechanical weeding on arable crops.
Practicing mechanical weeding of annual crops over the whole surface
Mechanical weed control in the open can be implemented in annual crops in pre-emergence or just after emergence. It can also be used in perennial crops to manage inter-rows. In general, it targets weeds at early stages, and will be more effective on dicotyledons than on grasses.
Practicing mechanical weeding on the plantation row in perennial crops
In perennial crops (vines, orchards and nurseries), superficial soil maintenance operations (5-8cm) can destroy weeds on the plantation rows. There are various ways of destroying weeds: uprooting, severing roots, burying vegetative parts, etc.
Using the "sandwich" method to weed the plantation row in perennial crops
The sandwich method is a technique for controlling weeds present on the row of fruit trees. It consists of working the soil on each side of the row (40 cm minimum, up to 1 m for wide stone fruit plantations) with a simple tool, leaving the central band of the row of grassy plantation over 20 cm of minimum width.
Weeding mechanically using agricultural robots
Regarding weeding, agricultural robotics has made enormous progress and now offers a multitude of weed control robots for different scenarios.
IWMGAME [perennial crops]: Several cards cover mechanical weeding. It has only curative effects eliminating weeds except “superficial tillage” that can have preventative effect on controlling weed emergence. Mechanical weeding can be used for annual or perennial weeds depending on the method. You can play it at every period, both negative or positive side effects can occur, depending on the method.
IWMPRAISE Inspiration Sheet: One IS describes mechanical weeding technologies on vineyards.
Practicing thermal weed control
Thermal weed control is a method of destroying weeds by heat. Weeds are destroyed not by combustion but by thermal shock: exposure to high temperatures causes damage to the plant cells of the affected parts (aerial parts), which leads to them drying out in the short term (of the order of a few days). So there is no need to "burn" the plants. On the other hand, the technique does not kill the roots and has difficulty controlling certain plants with a creeping habit or perennials.
It is carried out using gas or infrared burners.
Practicing electric weed control
Electric weed control involves passing an electric current through the plant. This action will destroy the emerged weeds, by bursting the cells due to the vaporization of the water they contain.
IWMGAME [arable and perennial crops]: Two cards represent physical weeding. It only has curative effects, eliminating weeds and only concerns annual weeds. You can play it at different periods. This technics provoke negative side effects.
IWMPRAISE Inspiration Sheet: Two IS describe thermal weeding with flame or hot water.
Management = Necessary to maintain and not be overwhelmed
Managing the grassing of perennial crops mechanically
The grassing of perennial crops must be regularly maintained in order to control the risk of the development of undesirable weeds. This maintenance can be carried out mechanically using mowers or mulchers.
Mechanically destroying intercrop cover and meadows
It is possible to mechanically destroy a plant cover or a meadow, rather than using glyphosate in particular. Grinding, scalping, rolling, stubble cultivation, ploughing, letting freeze, as many techniques as specific conditions
IWMPRAISE Inspiration Sheets: Our Italian colleagues describe a technic which combine two pieces of equipment to terminate cover crops.
Associating farm animals with crops
It is possible to associate farm animals with crops in order to control various pests. This allows, among other things, to reduce the phytosanitary pressure of certain pests or diseases, to "mow" grass in orchards or to depress cereals, or even to reduce the presence of rodents.
IWMGAME [perennial crops]: One card is represents this biocontrol approach during the inter-cropping period. It has only curative effects by eating present weeds. These methods have neutral side effects except on soil fauna, some beneficials may be affected.
Use natural substances with biocidal activity
Some natural substances can be used as a biocontrol product. These are substances present in the natural environment and may be of plant, microbial, animal or mineral origin. These substances can replace synthetic pesticides by their biocidal activity.
IWMGAME [arable and perennial crops]: One card represents physical weeding. It has only curative effects, eliminating weeds and only concerns annual weeds. As there is no selectivity on crops, you can play this card only during intercropping on arable crops while it is possible to use it at different periods on perennial crops. This approach may cause negative side effects.
Using biological methods against weeds
Development of biological weed control methods is not well advanced and studies of the effect of soil beneficial organisms as seed consumers are still in their early stages. Nevertheless, the interest of preserving a fauna having a totally or partially granivorous diet is increasingly studied.
IWMPRAISE Inspiration Sheet: One IS describes biological control with macro-organisms.
In crop mechanical weeding: how it works
A presentation by Will Smith, NIAB, Cambridge, England. The video is about two minutes long.
In crop mechanical weeding: in detail
A presentation by Will Smith, NIAB, Cambridge, England. The video is about seven minutes long.