Tobacco

Fungus Gnats

Bradysia matogrossensis

Insect

Heal your crop

Take a picture

See diagnosis

Get medicine

Get Plantix app

In a Nutshell

Small, mosquito-like insects.
Wilting of tobacco seedlings.
Often a problem in nurseries.

Can also be found in

1 Crops

Tobacco

Symptoms

To check if there are fungus gnats in your tobacco nursery: wave your hand gently above the seedlings and small black mosquito-like insects will fly away. The damage is caused by the larvae feeding in the root zone of the seedlings. They eat the roots of the seedlings, making the plants grow poorly, wilt, turn yellow, lose leaves, and eventually die.

Recommendations

Organic Control

Drench your seedlings with Bacillus thuringiensis israelensis. This can help in control of the larvae.

Chemical Control

Seeing adult gnats does not mean you immediately need to chemically control them. In small numbers they do not cause huge problems. Only use chemicals if you notice an increasing number of dead seedlings. Sprays can help control adult fungus gnats. Drenching appropriate pesticides can help control the larvae. When using pesticides or any chemical product, it is important to wear protective clothing and carefully read the label instructions. Regulations vary by country, so ensure you follow the specific guidelines for your area. This guarantees safety and increases the chances of successful application.

What caused it?

They thrive where standing water can be found, especially where dead leaves and organic material accumulate. This is why fungus gnats are common in nurseries where seedlings grow in trays that float on water. The adult gnat lays eggs in float trays, usually when seedlings are young, soon after seed germination. The larvae are tiny, transparent or whitish in colour with a shiny black head. They are not easy to spot with the naked eye but you can see tiny points moving in the soil around the rootzone.

Preventive Measures

Start early on with inspecting nurseries for flying adults or damaged seedlings.
You can also use yellow sticky traps for monitoring and mass trapping.
This is very helpful with these small bodied insects.
Make sure there are no puddles of standing water.
In pond systems with floating trays there should be no gap between the trays, as this is favouring algae growth, which the insects feed on as well.
In nurseries without standing water, avoid heavy irrigation.
Do not over-fertilize because it can cause excessive dead organic matter accumulation, which attracts these pests.