LO 2.2 - Effects of weeds Flashcards
- Competition - Pest and disease - Seed quality - Blocking drains - Poisonous plants - Machinery fouling - Aesthetics
1
Q
Name some adverse effects of weeds.
Seven points to consider.
A
- Competition
- Pest and disease
- Seed quality
- Blocking drains
- Poisonous plants
- Machinery fouling
- Aesthetics
Slows your brain down man!
2
Q
What do we mean by competition?
Explain Competition
A
Competition
- Weeds are responsible for 10% loss in crop yield (estimated)
- Weeds deprive the crop of water, mineral nutrients and light.
Yield reduction depends on:
- Competitive ability of crop in relation to the weeds
- Habitat, growth rate and density of the crop and the particular weed species present
- Season the crop is sown or planted
3
Q
Some Competition Examples
A
Competition examples
- Chenopodium album [Fat Hen] is a vigorous grower
- Stellaria media [Chickweed] can grow a relatively low temperatures and may suppress over-wintered crops
- Plantago [Plantain] forms a rosette with broad spreading leaves and is a problem in grass areas
- Trifolium spp. [Clover] is a very vigorous competitor of grass in a lawn situation
4
Q
What do we mean by competition for resources?
A
- It’s difficult to determine which of the factors water, nutrients or light has the greatest influence on crop growth.
- The net effect is what matters.
5
Q
Some examples of Competition for Resources.
A
- Weeds may absorb nutrients from the soil more rapidly and in larger amounts than the crop.
- Under conditions of moisture stress, deep rooted weeds such as Chenopodium album are less affected by shortage of moisture than many crops.
- Perennial weeds such as Convolvulus arvensis and Trifolum repens flourish in dry summers .
6
Q
Pest and diseases
Flip for up to 7 examples.
A
- Stellaria media (Chickweed) can harbour whitefly
- Wild species of Allium may harbour leek rust
- Epilobium (Willowherb) is a host for Fuchsia rust
- Sedge is alternate host of gooseberry rust
- Groundsel is alternative host of rust
- Bittercress is alternative host for powdery mildew
- Shepherd’s Purse can harbour club root of cabbage
7
Q
A couple of more problems
A
- Poisonous Plants • Fruits of Black nightshade (Solanum nigrum) may contaminate mechanically harvested pea crops for processing
- Machinery • Mowing machines and harvesting equipment may be blocked by weeds such as Knotgrass (Polygonum aviculare) which has stringy stems
8
Q
Consider for a moment…
Aestetics
A
