Wondering why the leaves on your birch tree are suddenly becoming brown?
It may be caused by Birch leafminer, Fenusa pusilla and the early signs of Birch leafminer feeding may have been missed. Early mines appear as light green or whitish discolorations on the leaves. Larvae sometimes can be seen easily when leaves are held up to sunlight, especially as the mines and larvae grow larger. Feeding over several weeks causes the blemish to take on a blister-like appearance. Over the season, the leafminer larva consumes the green tissue between the outer layers of the leaf resulting in browning.
An application of our Nematodes for Birch leafminer in late April to early May as soon as soil temperatures reach 100C (500F) can correct this pest.