Key Area 3.3 - Crop protection

what decrease the productivity of crop plants

weeds which compete with crop plants, while other pests and diseases damage crop plants

what are the two types of weeds

annual weeds and perennial weeds

Properties of annual weeds

rapid growth

short life cycle

high seed output

long-term seed viability

Properties of perennial weeds

they have competitive adaptations - storage organs and vegetative reproduction

what animals are most of the pests of crop plants

invertebrate animals such as insects, nematode worms and molluscs

what causes plant diseases

they can be caused by fungi, bacteria or viruses, which are often carried by invertebrates

how are weeds, other pests and diseases controlled

by cultural methods such as: Ploughing, weeding and crop rotation

what do pesticides include

herbicides to kill weeds

fungicides to control fungal diseases

insecticides to kill insect pests

molluscicides to kill mollusc pests

nematicides to kill nematode pests

what are the two types of pesticides

selective or systemic

about selective herbicides

they have a greater effect on certain plant species - broad leaved weeds

what do systemic herbicide do

spreads through vascular system of plant and prevents regrowth

what do systemic insecticides, molluscicides and nematicides do

spread through the vascular system of plants and kill pests feeding on plants

what are the problems with pesticides

toxicity to non-target species

persistence in the environment

bioaccumulation or biomagnification in food chains

producing resistant populations of pests

how could fungicides be used more effectively

by applying it based on disease forecasts making it more effective than treating diseased crops

what is bioaccumulation

its a build-up of a chemical in an organism

what is biomagnification

its an increase in the concentration of a chemical moving between trophic levels

how else can weeds, other pests and diseases be controlled

through biological control and integrated pest management

what is biological control

it’s when the control agent is a natural predator, parasite or pathogen of the pest

what is integrated pest management

its a combination of chemical, biological and cultural control

what are the risks with biological control

the control organism may become an invasive species, parasitise, prey on or be a pathogen of other species