crop protection Flashcards
Monoculture
A monoculture is the name given to single species grown over a large area
weeds
weeds compete for the crops resources such as water, lights and nutrients from the soil
They may also release chemical and inhibitors into the soil which affect crop plant growth, and can act as a host for pests and diseases
annual weeds
Annual weeds grow quickly, have a short life span and produce many seeds which are viable for long periods of time
Perennial weeds
Perennial plants live for many years becoming dormant in the winter and growing in the spring.
Some perennial weeds have competitive adaptations to ensure survival such as storage organs for food and vegetative reproduction
Pests
Pests of crops tend to be invertebrates as insects, nematode worms and molluscs
Plants pests eat the leaves of the crops which reduces their ability to photosynthesise this reduces yield ad vigour of the crop
plant diseases
plant diseases are often carried by invertebrates these diseases include bacteria, viruses and fungi
Control of weeds, pests and diseases
Different methods can be used to protect crops from harm these include cultural means, chemical means and biological means
Cultural means
ploughing a field can result in weeds being buried deep enough into the soil that they die and decompose
weeding can be used to remove weeds and prevent competition this should be carried out early in the life span of the crop plant
The perimeter of the field should also be weeded to remove hosts for pathogens
Crop rotation means that pathogens are unable to build up as they are not able to utilise the new crop
The use of leguminous plants in crop rotation allows for ore nutrients to be kept in the soil
Pesticides
Chemicals can be applied to crops to protect them from weeds and pests herbicides are chemicals used to kill weeds
Selective herbicides
Selective herbicides mimic hormones in broad leafed plants causing their metabolism to speed up
This results in them using all of their resources more quickly and they will die. Narrow leafed plants are not affected
Systemic herbicides
systemic herbicides are absorbed by the plant and enter its circulatory system.
This then has a lethal effect to the roots and leaves of the plant
Contact herbicides
Contact herbicides kill all green plant tissue they come into contact with
The roots can survive and the plant can grow back
Contact pesticides
Work in two ways
They kill the invertebrates they come in contact with directly or
leave a residue on the plants which will kill the pest at a later time
Systemic pesticides
Absorbed by the plant, they will kill any pests that try to eat the plant when they ingest plant material
contact fungicides
Applied to plant directly they will be absorbed by fungal spores as they start to germinate causing them to die
