lec 26 Flashcards
we love canola don’t we! except when we dont… why?
if u recall, spring wheat is grown in spring and canola is grown in summer. however, sometimes some leftover canola stragglers stick around, and soak up water and nutrients meant for the spring wheat without growing efficiently.
canola can become a weed where ur not trying to grow canola
this is called volunteer canola
what is a weed?
a species that has a perceived negative ecological or economic effect on agricultural or natural systems
why do weeds show up everywhere?
nature is inclined towards biodiverse communities, but we humans like agriculture with one crop at a time
–> weeds are not necessarily bad, just bad for us
in nature, weeds are good for reestablishing communities since they grow quickly and reprod lots, setting the soil for other plants
what are the four main traits of weeds?
- annuals w high seed production
- vigorous vegetation reproduction (regenerative ability)
- great longevity + weathering poor conditions
- high phenotypic plasticity
are weeds more native or introduced?
more are introduced than native
in north america,
- 39% are native
- 3% are from central/south america
- 35% are from europe
- 23% are found worldwide
what makes wild oat a weed?
annual that prod lots of seeds, has a longevity of 4 to 5 years, and is phenotypically resistant to most herbicides
what makes kochia a weed?
drought, frost, saline tolerant and herbicide resistant - hard to get rid of
what makes japanese knotweed a weed?
super thick and aggressive - hard to get rid of
compare and contrast oxeye daisy to scentless chamomile
oxeye has ‘spoonlike’ leaf shape and one single flower, and a really unpleasant odour
chamomile stem has multiple flowers per stem and no scent
what is poison ivy?
pest that can be found in every province except newfoundland
comes in three leaflets, which cause outbreaks of rash
what is giant hopweed?
weed common in south/central ontario
causes huge welts from sap (induces phototoxicity)
what is larkspur?
big cause of cattle poisonings bc cattle like it :3
what are the various ways weeds are spread?
- rhizomes
- stolons (aboveground stems ex strawberries)
- creeping roots (shallow roots)
- wind
- water
- burs
- animals
what are the effects of weed controls on plant growth?
when weeds are controlled, the desired plant grows a lot more
what are the four main ways to manage weeds?
mechanical: manually remove
chemical: herbicides
biological + cultural: prevention by checking seeds, as well as sterilizing soil and rotating crops
