My boxwoods are loosing their leaves and the ends of the new grown are curling. I think they have a leaf miner insect problem. What can I use to kill them and will they kill my boxwoods? I've only noticed them recently.
Around here boxwoods get spider mite VERY easily. This will make the leaves look like they are very finely speckled yellow. On the under side you can see fine webbing, and sometimes a mite. It may look like tiny white spots on the upper or lower surface.
Leaf Miners are fly larvae that are burrowing between the upper leaf surface and the lower leaf surface, leaving a track through the leaf. Not a hole. The leaf surfaces (top and bottom) are intact. It is the internal parts that are getting eaten.
Spider mites are difficult to kill. One way is to wash off the leaves. Mites seem to thrive in dry, dusty areas, and leaves that are near road ways often have a larger pest load than plants that are away from dust and drying conditions.
Leaf miners are just about impossible to kill. You could try systemic insecticides as long as the plants are not edible, and there are NO edible plants nearby that might pick up the poison.
Boxwoods are pretty tough, and have a good recovery potential. I would check again to see if you can actually see the pest, or see the damage. Bites out of the leaves? Leaves rolled and stuck that way with webbing?
One of the easiest ways to deal with a lot of pests is to hose off the plant with a pretty strong blast of water. You may have to repeat weekly or more often, though.
Try going out at night with a flashlight to ID the pests.
There are several things that attack Boxwood plants regardless of size or where they grow, I have lost last year about a dozen sculpted balls that I grew from cuttings about 10 years ago, they were just beginning to reach a nice globe shape/size when I first noticed browning at the tips of the little branches, then the leaves began to drop and the problem became evident, I had got the disease, Physiological Disorder that befalls box plants, also there are things like Box rust, this causes small dark brown , powdery spores on both top and bottom/underside of leaves.
Another problem for Box is Leaf Spot, this shows as pale brown spots. Occasionally there is a pest that comes affect Box called Box Suckers, they feed on the sap and turn the small leaf into a cabbage like appearance,. there is people who say that IF you catch all these things in the early stages and cut the damaged shoots off, then the plant will recover but mine has failed to recover and I need to burn my plants before it spreads to other people who grow box here.
Hope this helps you know what to look out for and deal with it before it is too late,
Best regards and good luck. WeeNel.