Pilchuck Pollinator

Cultural Controls:        

Maintain healthy plants by providing good soil drainage and adequate water and nutrients.  Stressed rhododendrons are more susceptible to disease.  However, avoid over fertilizing, especially late in the season, as this practice encourages soft new growth that is a prime target for Microsphaera spores.

Inspect your rhododendrons regularly to identify infected plants and problematic areas of the garden.

Move infected plants to areas that have less favorable conditions for the disease.  Be particularly careful to five plenty of space to R. cinnabarinum, R. thomsonii and their hybrids.  Try to plant them in ar3eas with a fair amount of sunshine and good air circulation.

Prune to increase air circulation.  At UBC Botanical Garden, they do nothing to rhododendrons to control powdery mildew other than occasional thinning of both the surrounding material and the rhododendrons themselves.

Remove old, heavily infected leaves from rhododendrons in fall or winter.  Rake up diseased leaves that have fallen under the plant and burn them or dispose of them in the garbage.

If all else fails, discard heavily infected plants and replace them with rhodys that are more resistant to powdery mildew.

The Most Massive Living Thing—A Fungus Among Us

Armillaria ostoyae, the fungus also known as the honey mushroom.

People have known about the honey mushroom for some time, but were unaware of how large and invasive it could be.  The fungus was investigated more closely by researchers when they realized that it was responsible for killing large groves of evergreen trees.  Researchers collected samples of the fungus from a widespread area and analyzed the DNA.  A large sample of the specimens they collected turned out to be from a single organism.  Until August of 2000, it was thought that the largest living specimen was one that covered 1500 acres found living in the state of Washington.  But then mycology experts surmised that if a specimen that large could be found in Washington, then perhaps one just as large could be responsible for the trees dying in the National Forest in the Blue Mountains of eastern Oregon.  Researchers were astonished at the sheer magnitude of the find.  This most recent specimen was estimated to cover over 2200 acres and be at least 2400 years old and possibly as old as 7200 years.

To go into the forest where this giant fungus makes its home, you would not look at it and see a huge, looming mushroom.  Armillaria grows and spreads primarily underground and the sheer bulk of this organism lies in the earth, out of sight.  Occasionally, during the fall season, this specimen will send up golden colored “honey mushrooms” that are the visible evidence of its hulking mass beneath.  Scientists have not yet begun to attempt to estimate the weight of this specimen.

How is it possible for a single fungus to get so big?  Scientists have postulated that it may be a function of the dry eastern Oregon climate.  Spores have a difficult time establishing themselves allowing the old-timers to spread unchecked.  And yes, the honey mushrooms are supposedly edible, but apparently not very tasty.