What are the most common pests and diseases when growing plants in controlled environments?

Growing plants in the lab, whether this is in growth chambers or in greenhouses, isn’t always easy. It is important to look for pests and diseases regularly to make sure the plants are healthy and to take care of any problem as soon as possible to avoid its spreading.🌱 

1️⃣Fungus gnats

Fungus gnats are mosquito-like insects from the Sciaridae family. These are probably the most common pests when growing plants in controlled environments. Usually, they are easy to spot, as the adults are often found flying around. Even though the adults are typically harmless they can, in some cases, carry diseases among plants. The real problem when it comes this pest is their larvae, which are known to eat the plant’s roots and leaves, posing a heavy threat to seedlings rather than bigger plants. Plants infested with fungus gnats display symptoms such as eaten leaves and very small root systems. Fungus gnats can be controlled using several methods, such as sticky traps, insecticides or biological control (nematodes, carnivorous plants, mites, etc).  

2️⃣Thrips

Thrips are tiny, slender insects with fringed wings which belong to the order Thysanoptera. They are easy to spot as the plants begin to show white and discolored spots in their leaves. This happens because thrips feed by puncturing the epidermal layer of the plant’s leaf, sucking out the cell contents. Thrips can be vectors for plant diseases and can be controlled using insecticides or biological control.  

3️⃣Aphids

Aphids are sap-sucking insects which belong to the superfamily Aphidoidea. Even though they do not commonly appear in growth chambers, aphids are a common pest in greenhouses. Plants infested with aphids usually display symptoms such as decreased growth rates, yellowing, browning, stunted growth, wilting, and low yields. Aphids are also known to frequently transmit plant viruses to their hosts and to excrete honeydew which often leads to the growth of fungi – sooty moulds – in the host plant. It can be difficult to control an aphid infestation due to its ability to rapidly increase in numbers by asexual reproduction. The most common ways of controlling this pest is by using insecticides and biological controls.  

4️⃣Powdery mildew

Powdery mildew is a fungal disease caused by many different species of ascomycete fungi of the order Erysiphales. Powdery mildew is very easy to identify as infected plants display white powdery spots on its leaves and stems. As fungi usually do, powdery mildew grows well in humid environments and produces spores which can be carried to other plants to spread the infection. Usually, this disease is controlled using fungicides.

Text by Clarisse Zigue  PhD Student EpiSeedLink Marie Skłodowska-Curie Actions

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