2103 - Plant Disorders and their Controls Flashcards
What is a Plant disorder?
Plant disorders are harmful disturbances of normal plant functions caused by environmental conditions.
Will have an Environmental, Genetic or Chemical cause.
- not contagious
- not infectious
- not caused by an infectious organism
- not a disease
Plant Disorders - Frost
- light case. Yellowing or Browning leaf surfaces.
- Severe cases. Wilting, Scorch and Blackening of non woody stems. Especially young foliage.
- May lead to death of leaves, stems and even plant.
- Severe frost may rupture Xylem/Phloem is trees and shrub, splitting the bark and allowing for secondary infection to enter.
Plant Disorders - Frost Control
- Follow correct hardening off procedure
- Avoid Frost Pockets
- Right plant in right place, not tender during cold spells
- cover at risk plants with fleece
- Glasshouses or Cloche
- Gas heaters
Plant Disorders - Shade
- Etiolation, leggy plants, spindly growth reaching for light.
- Stems bending towards light
- Poor flowering/Fruit production
Plant Disorders - Shade Control
- Right plant in right place
- Shade tolerant plants, Fatsia japonica
- supplementary lighting in glasshouse situation
Plant Disorders - Drought
- Drying curling leaves
- Wilt in non woody parts
- Bolting in some root veg
- Growth will be reduced
- Flowering fruiting reduced
- Dieback or death
Plant Disorders - Drought Control
- Drought tolerant species if prone
- irrigation system
- water when needed
- mulch to reduce water loss
- incorporate organic matter into the soil to improve water holding capacity
Plant Disorders - Waterlogging
- Growth will stop or cease (anaerobic)
- Wilting, yellowing of leaves
- Root rot (Ethanol)
- Oedema on leaf surfaces (water pressure exerted through leaf tissue)
- Death
Plant Disorders - Waterlogging control
- Plants adapted to boggy conditions (Lobelia cardinalis)
- improve drainage, or install drainage system (French drain)
- amend soil structure, if pan, caps etc are the issue
Plant Disorders - Temperature Damage
- Plant can’t transpire
- scorching, bleaching, death of non woody stems and flowers
- wilting
Plant Disorders - Temperature Damage control
- Shading, misting, dampening down
- Lowering temperature in glasshouse
- Do not expose plant to temperature extremes
Plant Disorders - Soil pH
High pH - Calcifuge plants suffer lime-induced Chlorosis due to unavailability of Iron in the soil.
Yellowing of leaves, interveinal Chlorosis.
Low pH - Calcicole plants, Chlorosis.
Plant Disorders - Soil pH Control
High pH
- mulch with pine needles
- feed with Sequestered Iron
- Add Sulphur chips to soil
Low pH
- add lime to raise pH
Plants right plants in the right soil pH
Plant Disorders - Fasciation
Caused by hormonal imbalances in the meristem cells. Can also be cause by genetic mutations and infections.
Shoots, flowers misshapen and distorted.
- pest attack
- exposure to chemicals
- damage to plant growing tip (frost?)
Plant Disorders - Fasciation Control
- avoid exposure to weed killers (drift)
- control environmental conditions where possible (cold, heat, insect attack)
- remove affected parts
Plant Disorders - Rose Balling
Caused by excessive rainfall, generally late in the season.
Outer petals get wet and prevent the flower form unfurling.
Subsequently rots and falls off. (rot is not the disorder)
Plant Disorders - Rose Balling
- Encourage good air circulation to promote drying
- Avoid watering roses from above
- cut back affected buts to prevent Botrytis
