(2020) Guide to Hydroponic pests and diseases
Introduction:
Growing with hydroponics can be a rewarding activity. You get the added benefit of larger plants with faster growth year-round when grown indoors.
However, hydroponic plants have pests and diseases that work their way into the system which can ruin your crop and your experience.
Sanitizing is key in successful hydroponics.
Outside soil gardens do not need it because there is an ecological system of checks and balances preventing any one thing from overwhelming an environment.
Controlled settings like indoor growing areas or greenhouses become overrun with invasive pests because they lack predators and environmental strain.
I have compiled a list of common hydroponic pests and diseases that I have seen so far in my hydroponic setups.
Table of Contents
1. Bacterial Diseases
Bacterial infections are the number 1 reason why my plants die in my hydroponic garden. They are always present in the system and will incubate and overrun your system if you give it opportunity.
Hydroponic Root rot
is a condition where bacteria coats and attacks the roots of the plant turning them brown, slimy, and fragile. This prevents the roots from absorbing nutrients and water resulting in the wilting of the plant.
Hydroponic Root Rot
Healthy Roots
Stagnant water in a warm and humid environment will always breed bacteria, so your nutrient water will regularly expire no matter what.
Solution:
What a Hydroponic Grower Should Look Like
You are a scientist growing food in a temperature-controlled lab and must be as clean as possible.
Never reuse a reservoir, container, net pot, or grow medium without washing and sanitizing first.
Keep plant debris out of the water as much as possible.
Keep the area swept and wiped down often.
Change the nutrient solution often. 2-3 weeks is average but do not go longer than 4 weeks. Make sure you sterilize the container while changing it out.
While changing the water, I wash it with dish soap and water, then spray the reservoir with 34% food grade hydrogen peroxide to kill as much bacteria as I can. Make sure you wear rubber gloves when handling! It causes temporary chemical burns.
Hydrogen peroxide chemical burn
You should get food grade hydrogen peroxide at your local hydroponics store because only 12% is available online.
Alternatively, you can use bleach for the same application. It is a lot easier to handle but is not as effective.
Most bad bacteria for plants are anaerobic, meaning they live in environments without oxygen. Therefore, adding an air bubbler to your hydroponic system aerates the water and dissolves oxygen back into the water reducing some bad bacteria.
For more information on root rot check out this blog.
2. Fungus and Mold
Without the proper precautions, fungus and mold can ravage your hydroponic system. They are airborne spores that are everywhere, so they will infect your system if you supply an environment for them to grow.
Dampening off
is a fungus that attacks young seedlings from the bottom. The young plant will be fine but then the bottom part will shrivel up, killing the seedling. There is no cure for a plant with dampening off, so prevention is key.
White Mold and Powdery mildew
breed perfectly in warm, damp conditions with stagnant air. They easily kill your plant if left unchecked.
Solution:
The main ways to prevent fungus, mold, and mildew is by adding lots of air circulation around your plants by a fan, keeping the humidity low, and using an inorganic growing medium.
I use a small circular fan to circulate air around my plants. Mold and fungus hate fresh air and cannot grow in this environment. This also helps with Calcium deficiency in plants later discussed below.
The only time I would allow the humidity to be high is when I germinate difficult plants. I remove the humidity dome as soon as I see sprouting.
I use temperature and humidity testers around the room to watch them. Luckily, my basement temperature stays the same year-round. However, my humidity swings from high in the summer to low in the winter. The heating and cooling effects in my house cause this natural outcome.
This is a good dehumidifier to trust.
ALROCKET Dehumidifier 35oz(1000ml) Small Dehumidifier for 2100 Cubic Feet (260 sq ft) Portable and Compact Ultra Quiet for Home, basements, Bedroom, Bathroom, Garage, Wardrobe, RV
Algae:
Algae can grow to the point where it will affect your tank’s Ph level drastically. It is an airborne spore and everywhere so if you expose your nutrients to light, you will have Algae problems.
Algae can come in several types and colors.
Some types are slimy, bubbly, float on top of the water, or coat the inside of the system. The colors can be green, pink, brown, yellow, or even purple.
Most algae have the same “fish tank” smell so if you are unsure if it is algae, take a whiff.
Ensure you are making sure light does not reach your nutrients and Algae will not be a problem. However, small amounts are inevitable.
3. Bugs
Aphids
are tiny green bugs that pierce and suck sap from plants and secrete a honeydew substance. They usually do not fly or move much unless overcrowding occurs. As aphids suck the juice from the plant, they cause stunted growth, leaf yellowing, and reduced yields.
The sugary substance they secrete attracts ants, which protect them in exchange for it.
Mold will grow on the substance if the ants do not get to it. Make sure you clean it up ASAP.
Whiteflies
are sap-sucking insects that live in thick crowds on the undersides of leaves. Disturbing infected plants causes great clouds of the winged adults to fly into the air.
Whiteflies also damage plants by sucking the juices from new growth.
Plants become weak and vulnerable to disease. Leaves may be sticky or covered with black sooty mold because they secrete mildew like Aphids.
They are also responsible for transmitting several plant viruses.
Solution:
Prevention is the best way to introduce these pests into your hydroponic system. Isolate plants that you want to introduce to your hydroponic system for a few weeks to check what pests or diseases that it may have. The only way these bugs can come in is on another plant or wearing dirty clothes from outside work.
Place sticky yellow paper around your grow area to capture pests and show early if you have a big problem. Fungus Gnats, Aphids, and whiteflies are all attracted to yellow so placing a few around will let you know if they are around.
Fungus Gnats:
Fungus gnats are small flies that overrun soil or grow mediums. Their larvae feed on fungi and organic matter in the growing media but also attack healthy roots causing a large problem to young plants.
I started with potted plants in my indoor garden and quickly found out that fungal gnats are a big problem.
Infested with fungus Gnats
I tried a lot of different things like drying out plants, spraying with hydrogen peroxide, apple cider vinegar traps, and gnat paper.
Nothing worked! They multiplied far faster than I could kill them.
Solution:
Using an inorganic growing medium like Rockwool will reduce fungus gnats from in your system.
Fungi is their main source of food, so removing any environment where fungus can grow is important. Fungi cannot make food for themselves as plants do, so they must steal it from a host like dirt or decaying organic material.
Plant Deficiencies:
Tip burn because of overcrowded plants
Not all plant problems come from pests. If the plant is not getting all the nutrients it needs, it will show signs of this. Correctly naming the deficiency is important in hydroponics and the successful growth of your plants.
Calcium Deficiency or “Tip burn”:
Calcium deficiency is most commonly related to low airflow around the leaf instead of inadequate amounts of calcium in the water.
Plants breathe and sweat just like us through a method called transpiration instead of perspiration. Except when a plant sweats, it cools the air around it instead of the plant. First, it takes in water and nutrients through the roots, then it moves it up through branches, stems, and leaves until what is unused or absorbed (about 95% of water) evaporates through “Stomata” or microscopic opening and closing mouths on the undersides of leaves.
If the plant cannot evaporate the water it releases, then the nutrients and water cannot move properly through the plant to the leaf tip, causing them to yellow. Transpiration is especially important in the rapid growth of plants caused by hydroponic methods.
Toxicity vs Deficiency:
It is easy to give to little or too many chemical nutrients to your plants. Here are some tips to prevent your nutrient solution from harming your plants.
1. Always buy chemical nutrients from a reputable supplier.
I only trust this 3-part mix for my plants and from this company. I have never had any problems using these concentrates.
General Hydroponics Flora Grow, Bloom, Micro Combo Fertilizer set, 1 Quart (Pack of 3)
2. Always follow mixing instructions carefully.
Sometimes you may need to convert measurements from teaspoons to tablespoons to supply the correct measurements to the water. I use a kitchen measurement converter my wife bought but you can easily look this up online. Never guess or “eh that’s enough”
3. Never add new nutrient water to old water.
Not all nutrients absorb evenly by the plant and some nutrients float easily and some sink. You will create a concentrate of certain minerals by adding water to water.
Nutrient water only has a usable life of a few weeks before it becomes overrun with bacteria and algae. The only way to remove them is to drain the water, wash and sanitize the container, and refill with fresh water.
Conclusion:
Knowledge is power! I wish I had known these things when I first started my indoor garden.
Tell me down below in the comments if this has helped, or if you have experienced any of these issues.
if you want to learn how I use Kratky to grow my plants, check out this blog.
