One of the reasons why watercress is easy to grow compared to most herbs is because it is rarely affected by pests and diseases. This is not to say that watercress is immune—they still get problems from time to time.
Here are some of the most common problems associated with growing watercress, how to recognize and control them:
This pest can cause considerable damage to your watercress once it gets infested. You would know flea beetles are feasting on your plant when you see smole holes on its leaves. Infestation of flea beetles usually happens twice a year—in April and July.
To control flea beetles, you can submerge your watercress in water for approximately two hours. This would make the fleas to float which makes them easier to remove.
You can also plant radishes nearby to lure this pest away from your watercress.
Aphids and Caterpillars
You would know if you have aphids among your watercress when you see clusters of small eggs just below the surface and at the tips of the leaves.
Severe infestation results in curling of the leaves. This pest suck out the sap from the cells in the leaves which can cause your watercress to weaken. The leaves may also appear shiny and sticky and would eventually rot and turn black because of fungus growth.
To prevent this from happening, place your watercress in a pond with sufficient flow or movement of water – submerging watercress is also a good control measure to prevent aphids and caterpillars.
You can also plant lettuce to drive these pests away from your watercress.
This is a fungal infection with symptoms that include losing a part—or in worse cases, all of the roots of your plants. Your watercress will start to lose vigor and eventually die.
The roots of watercress affected by “damping-off” look white that will turn brown later on.
To avoid watercress from this fungal infection, make sure to disinfect trays used in germinating seeds. Use only soil that has not been exposed to the fungus.