Lecture 11: control of crop diseases Flashcards
diseases are caused by:
fungi, bacteria & viruses (pathogens) –> they cause greater economic loss than insect pests
crop diseases are transmitted in a number of ways e.g.:
- in the soil
- in the air
- by a vector (i.e. insect)
3 important soil bored diseases in agricultural systems:
- Verticillium root rot (fugal,affects root first then spreads)
- Eye Spot (affects cereal plants)
- Clubroot (swelling, plant tumour)
2 airborne diseases spread by the wind:
- rust on wheat
- Powdery Mildew on barley
3 airborne diseases spread by the wind and / or rain splash:
loose smut on oats
- septoria leaf spot on wheat
- potato leaf blight
many plant viruses are spread by __ vectors
APHID
- they are viruses:
- -cauliflower mosaic virus on cauliflower and canola
- -turnip mosaic virus on cabbage
types of damage caused by diseases:
- acute damage
- chronic infection
- direct damage to produce
- post harvest damage
acute damage:
- leads to sever injury within a few weeks e.g. late blight of potato (Phytophthora infestans)
- caused the Irish potato famine of 1845-55. 1M people dies and another 2M left Ireland for Great Britain, Canada, and the USA
chronic infection:
gradually debilitates the plant and decreases plant productivity
e.g. apple canker caused by the fungus Nectria galligena
Direct damage to produce:
destroys or lowers its value e.g. apple scab, (Venturia inaequalis) or potato scurf (Rhizoctonia solani)
post harvest damage:
pathogens may be on the produce prior to harvesting or arrive post harvest e.g. green (Penicillium italicum) and blue (Penicillium digitatum ) mold on citrus or grain molds (various fungi)
who are FERA
monitors diseases of plants in the UK
methods of disease control:
- Cultural practices (rotation, sowing date, cleaning equipment, killing weeds which harbour disease, burning debris etc)
- quarantine schemes
- chemical control
- biological control
- traditional plant breeding themes (resistant cultivars)
- genetic engineering of crops for resistant
for plant quarantine to be effective __ must be for filled:
CERTAIN CONDITIONS
- pathogen must be transported on diseased material or by a vectors that can be controlled
- regulations must be relevant and sensible
quarantine can be enforced in ___ ways
several
- inspectors at ports and airports
- growers can only import stock from nurseries that are inspected for disease
- can be a very effective control measure if applied at the correct time
example of quarantine taking place now
a total ban on import of a specific host plant e.g. import of Spanish chestnut into the UK
-to prevent the spread of Chestnut Blight caused by the fungus Endothia parasitica
Ash dieback caused by fungus Hymmenoscyphus fraxineus: What is it?
die back of ash is a serious disease caused by the fungus Hymenoscyphus fraxineus
Ash dieback caused by fungus Hymmenoscyphus fraxineus: where is it found? And when was it discovered
ash trees suffering with infection have been found widely across Europe since trees started to die in large numbers in Poland in 1992
Ash dieback caused by fungus Hymmenoscyphus fraxineus: has caused:
widespread damage to ash populations in Europe
-between 60 & 90% of Denmarks ash trees have died
Ash dieback caused by fungus Hymmenoscyphus fraxineus: Ash is the ___ species in many ancient woodland in the UK
DOMINANT
Ash dieback caused by fungus Hymmenoscyphus fraxineus: the disease causes (affect to tree)
leaf loss, crown dieback, and tree death
Ash dieback caused by fungus Hymmenoscyphus fraxineus: in Feb 2012:
the disease was found in a consignment of trees sent from a nursery in the Netherlands to on e in Buckinghamshire
Ash dieback caused by fungus Hymmenoscyphus fraxineus:in October 2012
FERA scientists confirmed cases in E. Anglia which didn’t appear to be connected with imported trees
-Govenrment banned the import of ASH SEEDLINGS into the UK
Ash dieback caused by fungus Hymmenoscyphus fraxineus: controlled or spreading?
SPREADING
