Dutch Elm And Striga Flashcards
Dutch elm facts
Started in Netherlands 100% infection when it attacks Spreads rapidly 2 worldwide epidemics with one starting in 1972 Vascular with disease
Uses of elm
Medicine, paper, furniture, fuel,
Dutch elm disease cycle
Infected beetle enters tree and forms a tunnel to lay eggs
Larvae dig out galleries where the fungus develops
When the adults emerge they are infected with the fungus and spread to new trees
Fungus spreads to the xylem causing vascular rot, tree wilts.
Dutch elm control
Target beetle- pesticide, awareness,
Target fungus- fungicides, cut down infected trees
Mistletoe facts
Seen in myths and legends
Parasitises plants
1500 species, mainly in subtropics, but some in temperate
Red and white berry species common in north
Berries produced in Autumn and mature by winter
Mistletoe reproduction
Perennial, so still survives when branches die
Chlorophyll in leaves is functional
Mistletoe growth
Penetration pegs enter host
Absorbs nutrients and water from host plant
Connects to phloem and xylem
Produces holdfasts in bark to stick to trees
Mistletoe dissemination
Berries spread by birds through digestion and plumage
Mature seeds washed into lower branches
Seeds contain sticky viscin so berries stick
Striga facts
In developing countries-west Africa 49-100% crop loss Thrives in poor quality soil Thrives in sorghum Thrives in low rain
Strega growth
Flowered in 2-4 weeks
Seed pods contain 400-500 seeds, rapid spread
Hausterium produced that penetrates host to extract water and nutrients
Strings control
Crop rotation- different crop for two years reduces strife by 50%
Chemicals- not suitable for developing countries as expensive
Improve soil quality- difficult in developing as it reduces planting time
Pre plant herbicides- atrazine
2-4-d on Strega leaves
Plant resistant varieties, remove flowering plant
