Sustainability and Interdependence - Crop Protection Flashcards
monoculture
single crop species cultivated over a large area to improve efficiency of farming
weeds
unwanted plant in a monoculture which competes with the crop plant for resources
annual
weeds
- colonise before the growth of the crop
- rapid growth rate
- short life cycle
- produce large number of seeds which are viable for long periods of time
perennial
weeds
- live for more than two years and have adaptations which allow them to outcompete the crop plant
- possess storage organs which allow growth even when conditions are not ideal
- ability to use vegatative (asexual) reproduction
pests
organism which damages the crop plant and reduces plant productivity
most are invertebrates: insects, molluscs, nematode worms
diseases
pathogens
- caused by fungi, bacteria, or viruses which damage the crop plant and reduces plant productivity
- often carried by invertebrates but can be transferred through soil and air
control by cultural methods
definition
non-chemical methods of preventing problematic organisms from establishing and damaging the crop plant(s)
control by cultural methods
name the methods
- ploughing
- removal of weeds
- crop rotation and cover crops
- removal of alternative hosts
- destruction of crop residue
ploughing
control by cultural methods
top layer of soil is turned over to bury perrenial weeds which die and decompose
removal of weeds
control by cultural methods
removal of weeds early in the life of the crops to reduce competition and give the crop plant a headstart
crop rotation and cover crops
control by cultural methods
growing very different crops in successive years in a field prevents the build up of pathogens which could cause issues if the same crop was grown the year after
removal of alternative hosts
control by cultural methods
weeds are removed at the edge of fileds as they may provide a habitat for pests or vectors of disease
destruction of crop residue
control by cultural methods
stubble can contain fungal pathogens so stubble is removed or ploughed into the ground to prevent issues from arising
control by chemical means
chemicals can be used to control pests e.g. herbicides, fungicides, insecticides, molluscicides, and nematicides
selective
herbicide
stimulates growth until broad leaved plant weeds exhaust food reserves and die
e.g. preen
contact
herbicide
non-selective as it kills anything it touches but its effects are short lived as perrenials with storage organs are able to regrow
systemic
herbicide
absorbed by weed and spreads through the vascular system to destroy the whole plant and prevent regrowth
disease forecast
predicting when outbreaks of pathogens may occur and applying fungacides during these conditions to prevent an outbreak from occuring
problems with agrochemicals
- toxicity to non-target species
- persistence in the environment
- bioaccumulation
- biomagnification
- production of resistant pest species
toxicity to non-target species
problems with agrochemicals
pesticides can be poisonous to not just the pest but a broader range of animals including humans
e.g. dieldrin
persistance in the environment
problems with agrochemicals
some chemical do not biodegrade and remain in the environment for long periods of time
e.g. DDT
bioaccumulation
problems with agrochemicals
- if an organism absorbs a chemical from the environment at a faster rate than is is lost, bioaccumulation occurs
- over time the chemical can become toxic
biomagnification
problems with agrochemicals
chemicals can be magnified along food chains as the concentration of the chemical increases from one trophic level to the next
production of resistant pest population
problems with agrochemicals
- continued pesticide use exerts a selection pressure on the pest population
- few individuals are already resistant due to a random mutation so have a selective advantage
- resistant individuals are selected for and survive to breed the next generation
- over generations the resistant individuals increase in number to produce a pest resistant population
biological control
definition
reduction in a pest population by the deliberate introduction of one of its natural predator, parasite, or pathogen
biological control
problems
- may become a pest
- be invasive and reduce biodiversity
- could introduce parasites or pathogens
- my be a parasite to other organisms
- may distrupt food chains and webs
integrated pest management
IPM
combines cultural, chemical, and biological controls in a combinational approach to manage pest populations whilst reducing the impacts of management strategies on the environment
