Cereals Week 10 2024 Weed Control Part 1
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Why do we control weeds in crop production?
• • To reduce the competition effect • • Allow ease of harvesting • • Achieve high grain (seed) quality • • To prevent the build-up of problem weeds
What is a weed?
A weed can be any plant growing in the wrong place
What are huge problems in crop rotations?
In crop rotations volunteer weeds are big problems e.g. potatoes growing in a cereal crop, or wheat/barley growing in a bean crop etc
What are 2 effects of weeds?
• • Competitive effect : Crop Yield • • Ease of harvesting : Grain quality
What are the 3 weed types?
– a. grass weeds – b. annual broad leaved weeds – c. perennial broad-leaved weeds
What are key competitive weeds?
cleavers, wild oats, and strong grasses
Name 2 non chemical methods of weed control?
• Cultural methods • Cultivation practices
What are 4 cultural methods for weed control?
– Winter cropping and spring cropping – Rotations : use of break crops / root crops / grass – also fallow (set-aside) – Cover crop options
What are the 3 cultivation practices for non-chemical weed control?
– Ploughing to invert soil and bury weed problems giving 80/90% weed control for certain grassweed species – Minimum tillage with stale seedbed sequences – Stubble cultivation
Are cultivations negative or positive effects?
Cultivations can have negative and positive effects
What can weeds sometimes have ? why can they be stubborn?
Dormancy , they be stubborn and they wont grow
What are the 3 methods of weed control?
-Mechanical -Hand -Chemical
What are mechanical methods of weed control? (2)
– Topping of weeds (grassland / set-aside) – In growing crop its usually used as localised control of problem weeds (strimming)
What is Hand roughing for weed control methods?
– Roughing of wild oats – Very commonly used in parts of the world where farms are small and /or labour is cheap as a cost-effective alternative to expensive herbicides
How much chemicals do field crops tend to get?
– field crops tend to get at least one herbicide application on the growing crop
How much chemical weed control do cereal crops have? Whats used on them?
– in cereal crops usually 2 or more a.i.’s are applied in a single application • either as a tank-mix, e.g. Ally + CMPP • or as a formulated product, e.g. DFF + IPU
How much chemical is complete “between” crops ?
– Pre-harvest is commonly used on many crops / sometimes as a dessicant (oilseeds/potatoes) – On stubble etc glyphosate is widely used
Growing different crops are planned in what sort of a sequence?
• Growing different crops in a planned sequence across a farm area over a period of time (3-6/8 years)
What are weed control advantages? (2)
–flexibility of sowing date – winter/spring –cultivation method– root crop
What are the 2 opportunities for different chemical weed control strategies?
– - herbicides with different modes of action/spectrum – - pre-emergence and post-emergence options
Do all weeds germinate all year round?
No not all weeds germinate all year round. Polygonum weeds are spring germinating only
List the 4 important weed groups :
1* Annual grass weeds – meadowgrass’s / ryegrass’s 2* Perennial grass weeds – scutch (couch) / creeping bent/soft grass 3* Annual broad-leaved weeds – chickweed / cleavers / fat hen / charlock etc 4* Perennial broad-leaved weeds – docks / thistles / creeping buttercup
List Annual Grass weed groups? (2)
Meadowgrass’s / ryegrass’s
Lst 2 Perennial grass weeds?
– scutch (couch) / creeping bent/soft grass