Plants can be more susceptible to disease if weakened by environmental conditions such as too much shade, high humidity and crowded conditions. They are also more susceptible when weakened by nutrient deficiency or toxicity (too many nutrients) and poor pH.
There will always be some trouble with disease, just watch for it and take care of it immediately. Unfortunately many disease cures involve the use of harsh chemicals which you really do not want on your plants. A hydroponics garden can easily collect such chemicals in the nutrient solution with indiscriminant use and get into the plant cells - not something you want.
What To Do About Them
Try some less harsh solution first. My favorite all-purpose cure is to mix together water, baking soda, lemon juice and a very little dish detergent. I put this in a spray bottle and mist the affected parts of the plant. Sometimes it works like a charm and sometimes not. If you mix and use this recipe, make sure you cover all areas open to your nutrient solution or the dish detergent will get into it causing soap bubbles.
Diseases
Powdery Mildew
Description:
Fungus causing whitish spots on the underside of the leaves.
Eventually the leaves shrivel and die. Thrives in high humidity.
Treatment: Spray with
homemade all purpose cure described earlier.
Root Rot
Description:
Fungus rots a plants roots.
Treatment:
Cut away
rotted root portions and spray with a fungicide.
Early Blight
Description:
Dark brown spots on leaves, stems and plant fruit seriously
weakening the plant.
Treatment:
Treat with harsh chemicals (maneb,
zineb).
Black Mold
Description:
Sooty black or grayish white leaf growth.
Treatment: Gently wash
leaves and scrape off mold.
Anthracnose
Description:
Fungus caused by over watering where leaves
become marked with dark smears and shrivel. Hardly ever occurs in
hydroponics plants
Treatment: Spray with
fungicide and remove damaged leaves.
Damping Off
Description:
A fungus affecting small
plants where stems meet soil causing them to fall over and die.
Treatment:
Remove
diseased sections. If it has affected a significant number of
plants, replant in new soil and clean containers.
Botrytis
Description:
Grayish white, fuzzy leaf growth caused by
inadequate ventilation. Not common in hydroponics gardens.
Treatment: Increase
ventilation and remove affected
Rust
Description:
Slightly raised, powdery
red pustules on the
underside of the leaves causing them to turn yellow then brown and
die. Helped along by high humidity. Very contagious.
Treatment:
Apply harsh chemicals
like
zineb or maneb.
Club Root
Description:
Roots turn into a mass of club
shaped tubers. Plants may become stunted.
Treatment:
Dust with fungicide
Crown and Stem Rot
Description:
Fungus causes plant to turn pulpy and rot.
Treatment: Cut
away rotted plant
portions and spray with
a fungicide.
