Past paper September 2020 Flashcards
Name a glasshouse pest
glasshouse whitefly
two spotted spider mite
Name an outdoor pest
slug
cabbage white butterfly larvae
black bean aphid
methods of control for glasshouse whitefly minimising use of pesticides are:
introduction of tiny parasitic wasp Encarsia formosa before plants become heavily infected.
name a parasitic wasp
Encarsia formosa
how does Encarsia formosa control glasshouse whitefly?
they prey on whitefly scale nymphs
how can glasshouse whitefly be controlled other that with parasitic wasps?
good hygiene.
weed control in/around glass house to remove host plants
How can slugs be controlled in a natural way? (predator)
Microscopic nematode (Phasmarhabditis hermaphrodita)
hedgehogs
frogs
How do you apply nematodes to an area?
you can water them onto the soil from spring to early autumn.
Soil temp must be 5-20 degrees C
How does a nematode kill a slug?
It enters a slug’s body, and infects it with bacteria with causes a fatal disease.
apart from nematodes, how else can you kill a slug in a natural way?
-think about predators
attract hedgehogs into garden-they like log piles.
ponds with sloping sides- to attract frogs.
describe the lifecycle of a glasshouse whitefly
revise a diagram too
lay greyish-whire, cylindrical eggs singly or in circles on underside of leaf
Each female can lay more than 200 eggs
Males are rare-reproduction takes place without need for fertilisation
Eggs hatch into small crawlers (scale-like nymphs) which crawl around for a bit before they start to feed and become immobile
Nymphs are flat,oval shaped, whitish-green and 1mm long
final nymph stage is a PUPA and the adult whitefly emerges through a slit in the dorsal surface
How does temperature affect the lifecycle of the glasshouse whitefly?
The length of the lifecycle varies according to temps.
At 10’C the life cycle takes several months.
at 21’C it takes three weeks.
Describe how glasshouse whitefly feed including the damage they cause
feed by sucking sap of plants using a stylet.
That reduces vigour of plant.
Whitefly excretes a sticky, sugary substance called HONEYDEW onto upperside of the leaves enabling growth of a black sooty mould which reduces plants ability to photosynthesise.
Can also transmit virus from one plant to another by sucking sap with stylet
what is honeydew and how does it affect plants?
a sticky, sugary substance produced by greenfly.
On upperside of leaves enabling growth of a black, sooty mould that reduces plants ability to photosynthesise.
Name one disorder of a rose
Rose balling
Describe rose balling
flower but often feels soft/slimy to touch.
outer petals become dry/cris in places
bud may drop off or if remains on plant grey mould can develop causing it to rot.
but cannot open and looks unsightly.
Name one rose disease
Black spot
describe black spot on roses
rapidly enlarging purple/black patch appears on upper surface of the leaf.
leaf tissue around the spot may turn yellow and the leaf may drop off.
small black/scabby lesions can appear on young stems
badly affected plants can shed almost all leaves and vigour of plant is greatly reduced
what is a method of control for rose balling?
Plant rose in open site
remove overhanging branches of trees
Good air circulation important so flower buds can dry quickly-achieved by appropriate pruning.
water in evening to avoid hot/sunny conditions
water at base never on flower duds/foliage.
remove affected flower buds ASAP to avoid grey mould occurring
describe method of control for black spot on roses
all fallen leaves should be collected and destroyed by burning or local authority (C) in the autumn.
or bury leaves under a layer of mulch
Prune out all stem lesions in spring prior to appearance of new foliage
Older species roses are less affected by black spot
spray with a fungicide
what fungicide can roses be sprayed with to control black spot?
teb-ucon-azole concentrate
state the life span of club root
it is 20years
describe the life cycle of club root
in the presence of susceptible plant roots (brassicas) resting spores germinate and can swim towards the brassica -entering roots through the root hairs.
roots become distorted, swollen and form galls.
the pathogen produces more resting spores in the affected tissue
affected tissue rots/disintegrates and releases spores back into soil
spores lie dormant in the soil until brassicas are planted again
describe two control methods for club root
a very long crop rotation
control weeds esp. in brassica family (Capsella bursa pastoris)
Keep soil pH above 7.4 by liming-club root likes acidic soil
avoid transfer of disease via boots/toold/tractor wheels
grow plants in pots before transplanting so there’s a more establishes root system
grow resistance varieties
