VL4, VL5 - 10.10.24/17.10.24 Integrated weed management Flashcards
Key components of Integrated Weed management IWM
Identification of the weeds present
rop residue management
Competitive crop variety
Crop rotations
Effect of soil cultivation methods/cropping system on weeds
Stale seedbed/weed control before sowing
beneficial effects of cover crops
Mechanical weed control methods
Economic treshold
Map heavy infestations of particular weeds for patch treatments
There are beneficial species among the weed populations
Weeds = wildlife resource
Residue management at / after harvest
Volunteer crops in piles/swaths of straw and chaff (e.g. visible after harvest of winter wheat) germinate
When residues are evenly distributed, threshold for control is not reached, when not distributed, threshold for control is reached wihtin the swaths
Options in residue management
Chaff spreader
Heavy harrow
Tillage
basic soil cultivation and seedbed preparation before sowing are the most important measures for mechanical weed control
Thanks to tillage, the original vegetation has developed into today’s vegetataion
The weed flora of the field (mostly annual seed weeds) is adapted to tillage (bligate dormancy ensures survival of the species in a tillage system. It is broken in the soil by moisture, cold and - after tillage - by light)
Possible objectives of tillage
Einjährige Unkräuter bis 2-Blatt-Stadium bekämpfen
Einjährige Unkräuter grösser als 2-Blatt-Stadium bekämpfen
Mehrjährige Wurzel-Unkräuter bekämpfen
Bodenverdichtungen läsen
Saatbettbereitung
Unkrautkur vor Saat
Horizontale Verteilung von Pflanzenresten
Vertikale Verteilung von Pflanzenresten
Ausebnen der Bodenoberfläche
Depending on objective different machines can be used
Problems / dangers with tillage
Intensive cultivation (upside-down / moldboard plow tillage, high axle loads, PTO-driven soil cultivation equipment) haas recently (~30 years) led to increasing environmental problems: Soil erosion, compaction, clogging, water pollution
Today, tillage can often be done without regard to soil / weather conditions
Possible solution: reduction of tillage, no.till = most extreme but most effective measure -> conservation / regenerative agriculture
No tillage, dierct seeding, zwero tillage
weed seeds are no longer transported in the soil profile
weed seeds accumulate in the top layer of the soil
the reserve organs in the soil are no longer regularly destroyed
the soil is usually covered by a distinct mulch layer
Bilder
See pictures in slides
Comparison Intense tillage - Extense (no-)tillage
P. 25
Soil cover with plant residues: few - dense
Risk for soil erosion and clogging: high - low
Position of weed seeds in the profile: dispersed over the profile - on the soil surface
Typical weed species: annual dicotyledons, grasses (monoculture CR), perennial species (organic farming) - Surface germinatiors, Anemochorous species, volunteers, perennial species
Total weed abundance: rather high - with dense plant residues/cover crops rather low
Type of herbicide: Soil herbicide - leaf applied herbicide
Weed control at seeding of the crop: tillage - often non-selective herbicides
Reduced tillage systems
weed control by the plow is eliminated and must be replaced (non- selective herbicide, green manure, plant residues, multiple surface tillage)
equipment commonly used in plow cultivation for mechanical weed control is usually useless because of the mulch layer
Herbicides are often absorbed by the mulch layer and the effect of soil herbicides is usually reduced. Therefore, contact herbicides should be used more frequently where possible.
Cereal and foliar crops should always be alternated (volunteer crops)
when selecting varieties, care should be taken to ensure rapid youth development
Certain herbicides can lead to post-emergence problems under unfavorable conditions (late application date, dry weather) (especially sulfonylureas or triketones).
Conflict of interest - herbicide reduction and soil and resource conservation measures
Conclusions on use of cover crops
