Posted by: marinvit | June, 2010

Orchid Diseases-Ailments


Due to deficiencies or excesses of

– nutrients

– horticultural practises

– environmental factors


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


-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

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