Insect and Disease Fact Sheet Compliments of
New Century 
1-877-79TREES
Needle Diseases on
2-Needled Conifers in Ohio
Most
of the "disease" problems encountered on conifers in Ohio are
actually non-infectious disorders resulting from the plant being out of balance
with its environment. Dry weather will often cause browning of needle tips or
browning and drop of second year needles. Trees growing in sites which are wet
early in the year are less tolerant of summer drought. Such trees may rather
quickly turn yellow and die in the late summer. Nevertheless, some fungal
needle diseases of conifers can cause considerable damage in plantings
throughout Ohio. In such cases, control measures may be needed.
Lophodermium Needlecast
This needlecast disease is caused by the fungus Lophodermium seditiosum. Fungal
fruiting pustules develop on fallen needles over the summer. They show up as
black, football-shaped protrusions on the needles (Figures 1 and 2). From
August to October, during wet periods, windborne spores are released, which
infect the current year's needles, resulting in a small brown spot, often with
a yellow halo (Figure 3).
|
Figure 1. Fruiting pustules of Lophodermium
on pine needle. |
Figure 2. Close-up of Lophodermium
pustules. |
The
Spanish and French green strains of Scots pines have been especially hard hit;
other 2-needled pines such as red or Austrian may be infected. The small
yellows to brown spots become apparent on the one-year-old needles in March and
April. By May, many of these needles have turned brown and begun to fall off.
The defoliation may be more severe on the lower portions of the tree (Figure
5). As the new needles come out, the damage to the tree is often masked.
|
Figure 3. Infection spots of Lophodermium on pine needles. |
Figure 4. Yellowing of previous year’s needles caused
by Cyclaneusma. |
||
|
Cyclaneusma Needlecast This
needlecast, caused by Cyclaneusma minor, is also found on
Scots pine throughout Ohio. (This disease was formerly referred to as Naemacyclus, and this name may still be found in some literature.) In early
summer, yellowing of the previous |
|||
|
year's needles may be noted (Figure 4). Transverse brown
bands are often present on needles as well (Figure 6). The fruiting pustules
of the fungus are small, tan, elongate and protrude slightly above the needle
surface (Figure 7). They are seen on fallen or still attached brown needles
during a rainy or damp period. The most damaging period for infection by the Cyclaneusma needlecast fungus
appears to be on year-old needles in early spring. Most infections occur
before the current season's buds have broken. However, this fungus can infect
needles throughout the year during damp weather when temperatures are above
freezing. Infected needles will tend to drop throughout the year. Dothistroma Needlecast Dothistroma needlecast, caused by the
fungus Dothistroma pini occasionally
infects Austrian, red and Scots pine in Ohio. In late summer to early fall,
brown to reddish-brown spots or bands form on needles. The tips of the
needles gradually die and turn brown, while the base of the needle can remain
green. Small black fruiting bodies can be seen at the base of the infected
area. Spores are spread by splashing rain. Infection can occur on 2-year-old
needles from spring to fall. Current year needles can be infected beginning
in midsummer. They are not susceptible to infection until they have emerged
from the needle sheath. |
Figure 5. Defoliation of lower portion of pine caused
by Lophodermium. |
||
|
Figure 6. Brown bands transversing
needles of Cyclaneusma infected pine.
Figure 7. Fruiting pustules on needles of Cyclaneusma infected pine. |
Control of Needle Diseases Control
of these diseases involves cultural modification as well as chemical
protection. Scots pine should not be planted in areas that will be shaded from
the sun in the morning hours or in fog or dew prone locations. In plantations
where there are only a few diseased trees, remove them and burn them along
with their fallen needles. Do not allow weeds or tall grass to grow up around
the Scots pine. Thin plantings which are crowded. Prune trees appropriately
to promote air circulation within and among trees. Since these diseases
infect needles at different times of the year, it is important to determine
which disease is present before employing a fungicide. Laboratory diagnosis
may be needed. Colored spots or bands on needles can be caused by insects or
other injuries, and are not sufficient evidence of the presence of infectious
diseases. Fungicides
may be used to protect the needles from infection. Good coverage via wet down
hydraulic sprays is necessary. In all cases, read and follow the directions
found on the label of the product chosen. Treatment intervals will depend on
the product chosen and the amount of wetness during a given season. For Cyclaneusma needlecast,
fungicide sprays applied in early spring have prevented some damage in tests
conducted in Pennsylvania. Spraying when purple lilac buds show 1/8-inch
green beyond the brown bud scale may provide a timing tool in most areas in
Ohio. A second treatment should be applied in early May, and a third in
mid-June. This fungus can infect needles throughout the year; rainy summers
require additional treatments in mid-August and mid-October. For Dothistroma needlecast, treat
as new needles begin to emerge from needle sheaths, and again three to four
weeks later. Apply properly labeled products containing mancozeb or copper
compounds. Copper compounds may cause phytotoxicity,
so be sure to follow label directions carefully. |
||
Information through the Ohio State Extension Factsheet HYG-307l-96
Insect and Disease Fact Sheet Compliments of
New Century
1-877-79TREES