Problems in Hydroponics – Avoiding Common Mistakes

Plant diseases or blights in a hydroponics garden are much less frequent than in a dirt garden because there is no dirt to grow bacteria. Not to mention the fact that many plant diseases travel to the plant from the surrounding soil.

Infectious Disease in Plants

The cause of all plant diseases can be narrowed down to 1 of 5 categories:

• Fungi – members of the plant kingdom, they attack and feast upon other plants to obtain food,
• Bacteria – microscopic single-cell organisms that enter the plant through ‘wounds’,
• Viruses – cell walls of plants provide a natural barrier against viruses,
• Water Molds – small organisms that resemble fungi but are distinctly different,
• Nematodes – soil based roundworms.

Plant disease cannot occur without a host plant, a pathogen and favorable environmental conditions.

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…

I usually 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.

Bordeaux Mixture

A mixture to the ratio of 4-4-50 is prepared of 4 parts (6.5 cups) copper sulfate or bluestone, 4 parts (6.5 cups) lime and 50 gallons of water.

The home hobbyist can make a smaller batch for a hydroponics garden using 2 tablespoons copper sulfate, 2 tablespoons lime and 1 gallon of water. This mixture does not store well so be sure to use it the same day.
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.

I usually have to use a harsh chemical twice a season in my hydroponics garden in which case I cover the base of the plant and any open nutrient solution and spray sparingly.

An all-purpose approach to plant disease, unfortunately not very organic, is the Bordeaux mixture consisting of finely ground lime and copper sulfate.

This mixture has been used as a foliar spray for fungal infections for over a century; mainly in vineyards in France and is very effective. Its main drawback is the leaching of the copper into groundwater.

A new approach to plant disease control is really a ‘rediscovered’ approach known as biofungicide. This is a method of attacking plant infection through the use of naturally occurring and unmodified bacteria and fungi.

Sometimes it can be hard to distinguish between a nutrient deficiency, pest or disease but with experience you will be able to make an educated guess.

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The following table will list some of the most common plant diseases.

Disease	Symptoms	Treatment
Rust	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.	Apply harsh chemicals like zineb or maneb.
Club Root	Roots turn into a mass of club shaped tubers. Plants may become stunted.	Dust with fungicide.
Damping Off	A fungus affecting small plants where stems meet soil causing them to fall over and die.	No treatment.
Crown and Stem Rot	Fungus causes plant to turn pulpy and rot.	Cut away rotted plant portions and spray with a fungicide.
Root Rot	Fungus rots a plants roots.	Cut away rotted root portions and spray with a fungicide.
Powdery Mildew	Fungus causing whitish spots on the underside of the leaves. Eventually the leaves shrivel and die. Thrives in high humidity.	Spray with homemade all-purpose cure described earlier.
Early Blight	Dark brown spots on leaves , stems and plant fruit seriously weakening the plant.	Treat with harsh chemicals (maneb, zineb).
Black Mold	Sooty black or grayish white leaf growth.	Gently wash leaves and scrape off mold.
Anthracnose	Fungus caused by over-watering where leaves become marked with dark smears and shrivel. Hardly ever occurs in hydroponics plants	Spray with fungicide and remove damaged leaves.
Botrytis	Grayish white, fuzzy leaf growth caused by inadequate ventilation. Not common in hydroponics gardens.	Increase ventilation and remove affected leaves.

Rust fungus

Rust fungus is another common garden fungi causing reddish-brown spots on the underside of leaves and plant stems. It grows faster in hot, humid weather, and once the infection takes hold the plant will be destroyed quite fast.

This is a picture of rust. As I checked outsources for the treatment of rust I could not find much other than … ‘plant rust-resistant varieties’ which is not a big help when you become infected with it and need to deal with it.

Being a fungus, this infection is caused by a variety of different fungi that all seem to be plant-specific meaning that an infected species of plant will not infect a different species of vegetable.

As a sidenote fungi, like rust, are members of the plant kingdom but they do not contain any chlorophyll so they cannot manufacture their own food. They obtain their food by attacking other plants and feeding on them for energy.

So what do you do when you detect rust on your plants and want to get rid of it?

First of all, clip all infected leaves and other infected parts of the plant and do it quickly – the rust fungus grows extremely quickly. Next, keep the plant dry and apply a fungicide.

You could use a harsh chemical but, no need, because rust can be treated with less toxic chemicals.

Traditionally an infected plant is also kept out of the rain and not watered from above because the rust spores can keep reinfecting a plant by splashing in the soil around the plant base. Fortunately, this is not really a concern with hydroponics.

Rust fungus is best controlled by applications of sulfur and with neem oil. Common household ingredients can be effective against rust by mixing them with water and straining them into a spray bottle to be sprayed on your infected plant.

When mixing up a cure I combine the ingredients in a container and let sit for a few hours. Then I strain the mixture through cheesecloth into a spray bottle.

Treatment is applied several times a day for 7 days before you are successful and rust is eradicated.

And I cannot stress this enough: before applying any chemical of any kind to your plants, ALWAYS apply it to a small section first to make sure your plant leaves can tolerate it.

Included below are some common recipes that are very effective against fungi. Mix the ingredients, let sit in the sun, if possible, for about six hours, and strain.

When you devise your own fungicide mixture, keep in mind that water is a good base mixer as well as tea and oil will not only help the mixture stick to the leaves but will also smother the fungi. A squirt of liquid dish soap will also help the mixture stick to the leaves. So feel free to mix and match ingredients.

1 teaspoon neem oil1 pint water	Works well by itself or can be used in combination with other ingredients.
1 teaspoon neem oil1 pint chamomille tea	Chamomile tea is an effective fungicide by itself along with neem oil.
3 cloves garlic, choppedsquirt of liquid dish soap2 pints water	Garlic contains sulfur which powdery mildew does not like.

How to Cure Damping off

Damping-off is a general term used to describe the sudden death of seedlings. It actually refers to several fungal infections and plant diseases.

Many times when I’ve germinated a seedling from seed it will suddenly wilt and die for no apparent reason or it will just fall over with a pinched area on the stem at the soil line and die.

Sometimes a seed will rot before germination or an apparently healthy seedling will appear ‘stressed’ but will survive to become a dwarf.

What causes it? Since this may be one of several fungal infections it is still caused by fungi and treated with a fungicidal spray.

The key is vigilance…if you can catch a sickness as soon as it presents and treat it, you may save the seedling. Unfortunately, most fungal infections seem to progress with super speed.

Like many plant infections, the best treatment comes from prevention. Purchase and plant disease-free seeds which are those with a fungicidal coating.

If you are using seeds given to you from someone else or seeds you have saved from your harvest then apply your own fungicidal coating by soaking them in 1-gallon water with 1 teaspoon bleach for 15 minutes before storage.

When watering seedlings, add 1 tablespoon vinegar to 1 gallon of water to maintain an acidic pH which the damping-off cannot survive in.

You can also sterilize any soil you use for germination by placing soil as well as containers into the microwave for sterilization. Add 1 cup water per a half-gallon of soil and microwave on high for 8 to 12 minutes.

Another means of prevention is to avoid excess watering and overcrowding of seedlings (I am personally guilty of overwatering seedlings).

Mist seedlings with chamomille tea or clove tea and lightly dust the soil around the base of the plant with cinnamon or powdered charcoal (just do this once though).

As you can see, prevention is the key to stopping this and any fungal infection before it can take hold. Good luck and let me know of problems…

How to Get Rid of Powdery Mildew?

Powdery mildew is a common fungal infection causing whitish, powdery spots on the leaves of susceptible plants. And plants susceptible to this group of fungi include melons, cucmbers, squash, pumpkins and roses to name a few.

Pictured here is what powdery mildew looks like; you have probably seen it before… in fact it is one of the oldest recorded plant diseases.

This infection is caused by a variety of different fungi which, on the bad side, is why it is so common. However, on the good side, each fungal type will only affect a specific plant. This means that an infected cucumber will not cross over and infect a squash.

So what causes it? Damp weather with summer temperatures, plants planted too closely together and plants that get a lot of shade all contribute.

And once powdery mildew begins to form it grows really quickly; a full blown infection can occur within 72 hours.

But this fungal infection can be easily treated and without the use of harsh chemicals. These fungi seem to require damp conditions to take hold but, paradoxically, require a dry leaf to grow. And it does not like sunlight.

This is a picture of one of my hydroponics cucumber plants after a devastating bout with powdery mildew. The mildew comes on fast and must be treated early or it will result in extensive damage as shown.

Since the fungus grows so fast I simply did not notice it until too late (it had a full 24 hours to take hold). I did treat it successfully but the damage was done.

The powdery white/gray spots will destroy the leaves and inhibit photosynthesis effectively destroying the plant.

So if you cannot catch this fungus early, your plant’s leaves will look like my poor cucumber leaf pictured here…the only cure now is to remove the infected leaves.

Powdery Mildew, begone!

Common ingredients used to combat this nuisance fungus:

• Potassium Bicarbonate, found in baking powder and antacids, will quickly destroy this fungus possibly by rapidly changing the ph of the plant leaf surface,
• Neem oil is a natural fungicide. Not only an effective fungicide it also helps coat plant leaves when sprayed suffocating the fungus,
• Hydrogen peroxide will cause oxydation of the fungus cell walls, killing it,
• Sulfur has been shown to be effective against the fungi,
• Milk seems to inhibit the fungus from growing – why? I am not sure…,
• Cornmeal soaked in water attracts another kind of fungus that kills powdery mildew.

So what can you do to eradicate this nuisance fungus? It can be treated with a mixture of mild household products.

Treatment may have to be applied several times a day for a few days but keep with it and you will be successful.

And I cannot stress this enough: before applying any chemical of any kind to your plants, ALWAYS apply it to a small section first to make sure your plant leaves can tolerate it.

The common ingredients effective against powdery mildew described can be mixed with water and strained into a spray bottle and sprayed on your infected plant.

I will mix the ingredients in a container and let sit for a few hours. Then I strain the mixture through cheesecloth into a spray bottle.

Included below are some common recipes that are very effective against the fungi. Mix the ingredients, let sit in the sun, if possible, for about six hours and strain.

The ingredients in the following recipes can serve as a guideline when you devise your own fungicide mixture. Keep in mind that your goal is to either change the ph or directly attack the fungi. Water is a good mixer as well as tea, oil will help the mixture stick to the leaves and will smother the fungi. And soap will also help the mixture stick to the leaves. So feel free to mix and match ingredients.

1/2 cup milk1/2 cup water	Equal parts of milk and water are very effective.
1/2 teaspoon potassium bicarbonate1 gallon water	A .5% solution works the best.
1 or 2 teaspoons baking powder1/2 gallon water	Baking powder contains potassium bicarbonate.
1 teaspoon neem oil1 pint water	Works well by itself or can be used in combination with other ingredients.
1 tablespoon hydrogen peroxide1 gallon water	A 2% solution works the best.
3 cloves garlic, chopped1 pint water	Garlic contains sulfur which powdery mildew does not like.

Molds and Fungi Growth in Hydroponic

Black mold, a fungus otherwise known as Aspergillus Niger, is a black, dusty fungal growth most likely seen on onions and garlic. Not to be confused with ‘black rot’, this fungus affects mostly stored vegetables and fruits.

Here is a picture of the fungal infection which you have probably seen before; that dark, dusty powder in between onion scales and garlic cloves.

Left unchecked, this fungal infection will consume the entire fruit it affects, turning it black and making it susceptible to any of a large variety of secondary infections.

It is completely preventable and usually occurs in vegetables that have been stored improperly in high temperature, damp conditions. And it very rarely occurs in the field.

It infects vegetables through wounds and is dispersed through spores from infected plants. Once a plant is infected fungicides are somewhat effective but there is no specific chemical that will control black mold so prevention is the best way to attack it.

For home hydroponics systems, this fungus is easily prevented through the use of seeds treated with fungicide and making sure to harvest in dry conditions.

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As a side note, the black mold fungus, Aspergillus Niger is commonly used in many commercial preparations. It is an ingredient in the production of citric acid and high fructose corn syrup. And it has been used historically in the preparation of Chandoo opium.

Rescuing Tomatoes From Late Blight

Tomato blight is a rapidly spreading fungal infection which I recently experienced first-hand in my hydroponics garden. I was growing a patio tomato in an ebb and flow container system and, initially, the plant grew rapidly with lush foliage.

In fact my patio tomato plant, which reaches an average size of 2 feet (.75 meter), reached a height of 6 feet (2 meters).

But, the growing season here could be summed up in one word….rain. In fact we received more rain in July than in the past 100 years of recorded weather history. This, combined with a nationwide tomato blight in America, doomed my tomato plant.

Here are some pictures of my diseased tomato plant. The blight, which is spurred along by damp conditions, took hold and darkened the stem of my plant, spreading to the leaves and finally to the small tomatoes.

I tried to clip all the diseased branches but the fungus still spread, eventually turning the plant into a soggy, rotten mess.

Shortly after these pictures were taken I destroyed this plant being careful not to throw it on my compost pile.

This fungal infection seemed to only affect tomatoes but can seemingly spread to peppers as well. Fortunately my pepper plants were still unaffected by this disease.

So what can be done to prevent or treat this disease?

From what I can find out….not too much.

I do know the fungal infection must be treated early before it really has a chance to take hold and it seems that only harsh chemicals are effective means of treatment.

I would love to hear some treatment options from some of you who have experienced this problem before.