One of the most common problems with growing plants is pests. Some are easy to control, but some require a special approach. This post will discuss one of those.
QUICK ANSWER: Pick the most active adults with your hands at night to get rid of the weevil on Coral Bells. Also, spray heuchera with a systemic insecticide and water it with an aqueous solution of beneficial nematodes to kill the grubs.
Pest description
Read also: How to Grow Coral Bells Successfully in the Garden.
The weevil (Otiorhynchus sulcatus) is a somewhat secretive insect. It comes out to feed only at night, thus eliminating the possibility of being eaten by birds. As a result, you will not see it unless you go into the garden with a flashlight at night.
This pest has an oblong body about half an inch long. The color is black to dark gray or brown. It has six paws that allow it to move quickly.
Adults prefer the leaves of Coral Bells, while grubs feed on roots. One female can lay about a thousand eggs. Once hatched, they can destroy the entire heuchera root system.
This pest affects some ornamental plants. But the most severe damage it does to agriculture.
Symptoms
The first sign of weevils is a gnawed leaf edge. After a while, it becomes dry and brown, and the leaf looks notched.
Over time, the leaves become more damaged, but you won’t notice the pest because, as I mentioned earlier, it only comes out in the dark.
A sign of weevil larvae is the slow growth of the heuchera. If this happens, the stem may lose its upright position and bend to the ground.
Also, the leaves will brown on the edge or droop along with the leaf petioles. This is because the roots are gone, and the plant has nowhere to take up water.
How to deal with adult weevils?
The first thing you can do is to collect the weevil by hand. Wear gloves and take a flashlight. Go out in the evening when it is dark and examine your heucheras.
If you see black beetles, collect them in a jar with a lid or other airtight container. Then destroy them all. If you leave at least one alive, the population will quickly resume.
For potted Coral Bells, you need to use bug tape. Simply wrap the tape around the top of the pot from the outside. Since weevils can’t fly, they will stick to the tape and can easily be picked up.
Systemic and contact insecticides are the most effective ways to kill adult beetles. However, because these products are unsafe for pets, they are not readily available everywhere.
Unfortunately, organic pesticides such as neem oil do not work against weevils.
How to deal with weevil grubs?
If the weevil damages your heucheras leaves, the females have likely already laid eggs around the roots. It is only a matter of time before the larvae hatch and destroy the roots.
In this case, you should not wait for Coral Bells to suffer; instead, you should use beneficial nematodes. Suppliers on the market offer products that work well against not only weevil larvae but many other bugs.
Prepare an aqueous solution with the nematodes as labeled. Apply only in warm weather. Water all your heucheras abundantly with this solution. The nematodes will then enter the soil and kill the grubs.
If the roots are already damaged, dig up the plant and clean the dirt from the roots. Wash the wounds and plant the bush in a new location. Collect all grubs and destroy them.
How to prevent the spread of the vine weevil
The first thing to do to prevent weevils from getting into your yard is to buy only healthy plants. This is not only true for Coral Bells.
Before you buy, scrutinize the plant for insect damage to the leaves. Pull the plant out of its pot and examine the roots to see if there are larvae. Look for another supplier if there is even the slightest trace of pests.
Preventively use weevil traps. Traps can catch the first ones even if they are not in your garden.
Also, if there is the slightest suspicion that weevils are present, don’t wait for the population to increase; use beneficial nematodes wherever possible.
What to do with damaged Heuchera?
If the weevils damaged only the leaves, Coral Bells will recover after some time. To ease the recovery process, water the plant with a liquid multipurpose fertilizer and repeat this after some time.
Keep to the proper growing conditions; after a while, it will look like nothing has happened.
If the grubs have damaged the roots, dig out the bush and remove the dirt. Wash the roots with water and treat the wounds with an aqueous hydrogen peroxide solution.
Plant it in the clean substrate and move it to full shade. Wait for the plant to fully recover before planting it in the garden.
If the heuchera has fallen to the side and the grubs have eaten all the roots, you must re-root it. Divide the bush into several pieces, the larger the pieces the faster they will root.
Plunge the pieces into sterile potting soil. Use pots about 5 inches across. Put them in a dark place. Once an entire root system is formed, Coral Bells can be planted permanently.
Read more: What Bugs Eat Heucheras?
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