AILMENTS
Due to deficiencies or excesses of
- nutrients
- horticultural practises
- environmental factors
WATER
Over watering – insufficient oxygen to the roots caused by too high a water holding capacity of media
- impervious (to gaseous exchange) pots
- over potting
- drying prevented by insufficient air movement
Symptoms – older leaves yellow & shrivel
- roots rot and die
Cure – unpot , cleanup, high humidity, lower light
Under watering
- insufficient moisture retention of media
- rarely inadequate frequency or amount
Symptoms – shrivelling of plant
- brittle papery roots
Cure – water lightly, second watering 1 hour later, may need a third, soak individual plants up to 1hour
Water quality – suitability of water
- measured by electronical conductivity i.e. the soluble salt content
HARD WATER - high content of calcium & or magnesium salts
- reduce misting or syringing – deposits on leaves
- at greater than 300 ppm, soap does not lather
Control – acid media e.g. peat moss
- fertilizers with high residual acidity, leaching important
SOFT WATER – high content of sodium salts
- high ec , may be toxic to plants,
- leaf & root tip burn
-can use resinous demineralisers
LIGHT
-measured in foot candles, 1000 ft candles = 10% full sun
-plants may tolerate higher light than that required for optimum growth
- various species & hybrids have different requirements & tolerances
Excess – tolerance dependant on facilities for dissipating heat from leaves direct result from light
- e.g. air temp, humidity, air movement tolerance
- sunburn due to perpendicular suns rays
- pale green & dull leaves , pseudobulbs shrivel
Minimal – due to excessive shading,
- dark green & weak spindly growth
- blind growths reduced flowering
