Balsam fir needle casts were spotted in Carlton and St. Louis Counties
on understory balsam fir trees.
Aspen leaf blotch miner populations are very, very low this year statewide.
Spruce budworm defoliation has intensified in north central counties
compared to last year's levels.
Lots and lots of oak anthracnose, the mid-summer type of infection,
occurring throughout the state due to wet weather during the past few weeks.
Ash anthracnose in northwestern counties.
Dioryctria damage to red pine shoots very high this year; in Sherburne
County, its nearly 25% of the new shoots infested. Notable damage to red
pines in Benton, Crow Wing, Pine, Itasca and Carlton Counties.
During aerial surveys on July 15th and 17th, trees succumbing to oak
wilt and Dutch elm disease were easily discerned in Sherburne, Benton and
Stearns Counties.
Pale green weevils are again actively feeding on the edges of hardwood
tree and shrub leaves and crawling all over people in Itasca County.
A few sugar maple trees across southern Minnesota (both urban and rural
areas) are dying from Armillaria root disease. With the abundant rainfall
and accompanying high dew points the incidence of Armillaria seems to have
increased. The individuals that are dying are likely weak trees or trees
weakened by recent stress events such as the previous severe winter. When
dryer conditions return in August the symptoms of maple decline will be
more evident. Symptoms of maple decline include early fall coloration,
leaf defoliation, and branch dieback.
The time to fertilize trees is past now until this fall. Midsummer
fertilization is discouraged as it may force a spurt of shoot growth that
will not harden off in time for winter.
