Arborvitae Diseases
| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Branchlet Death |
The oldest branchlets turn brown in autumn and
fall off. |
Normal browning |
Branchlets rather than scale leaves are shed
in autumn as a normal part of the plant's development. |
| Kabatina Twig Blight |
Tips of 1-year-old branches die and turn brown
or ash-gray. These remain on the shrub for many months. Larger
branches can be invaded and girdled. On the dead tissue where
it meets the still-living wood, small, black, pimple-like fungal
fruiting structures form. Microscopic examination reveals oval,
colorless spores. See Phomopsis below. |
Kabatina thujae |
Prune and destroy infected twigs and branches.
It is possible for both Kabatina and Phomopsis twig blight to
occur on the same plant. If only Kabatina is present, apply
mancozeb to protect foliage. |
| Pestalotiopsis Tip Blight |
Twig tips turn tan to brown in color and have
black, pimple-like fungal fruiting structures dotting their
surface. |
Pestalotiopsis funerea |
Protect plants from winter injury, drought, and
other stresses. Apply copper to protect foliage. |
| Phomopsis Twig Blight |
Tips of branches die and turn brown or ash-gray.
These remain on the shrub for many months. Larger branches can
be invaded and girdled. On the dead tissue where it meets the
still-living wood, small, black, pimple-like fungal fruiting
structures form. Microscopic examination reveals both oval and
long, thread-like colorless spores. See Kabatina above. |
Phomopsis juniperovora |
Prune and destroy infected twigs and branches.
It is possible for both Kabatina and Phomopsis twig blight to
occur on the same plant. If only Phomopsis is present, apply
azoxystrobin, thiophanate methyl, or copper when new growth
is present. |
Fungicides mentioned above:
| COMMON NAME |
TRADE NAME |
| azoxystrobin |
Heritage |
| copper |
Kocide, Basicop, Microsperse, Nu-Cop |
| mancozeb |
Dithane, Protect T/O, Pentathlon |
| thiophanate methyl |
Clearys 3336, Domain FL |
| 
