Nature Notes

Vol. II January-February, 1987 No. 11


Why are chains required to get to Paradise on days when there is less snow than other days? Blame it on "amorphous ice!" Regular snow is formed by sublimation -- the process where water vapor freezes directly into hexagonal snow crystals. These crystals band together as snowflakes which further band together as layers of snow.

However, amorphous ice is frozen water and has no structure. Examples include sleet, hail, and icicles. When the upper layer of snow on the road thaws during the day and freezes at night, it loses its compact hexagonal structure. The resulting amorphous ice will not stick to other snow crystals, car tires, or boot soles. The solution? Keep the temperature below freezing to maintain the integrity of your snow crystals!

Lynn Arthur


When I first came to the park I was awe-struck with the beauty and splendor of the trees. But something was missing -- where were the pines? Being a lover of pines, I questioned why they were so sparse. My question was finally answered towards the end of the summer: White Pine Blister Rust.

White Pine Blister Rust, Cronartium ribicola, is a fungous disease which preys upon all five-needle pines, those most affected being Western and Eastern White Pines and Sugar Pine. The fungus starts with the needles and multiplies until the foliage is gone. Then it gets into the stems causing them to bulge and crack before dying. The spores eventually reach the cambium or reproductive layer in the trunk where they kill the tree by girdling it.

The Blister Rust, believed to have originated from Swiss Stone Pine, was first discovered in 1854 in the Baltic Provinces of Russia and it quickly spread throughout Europe. It didn't reach North America until the turn of the century when infected White Pine saplings were imported from Germany. The disease quickly spread through the East Coast and headed westward. It wasn't until the 1920's when a diseased shipment from France arrived that the Northwest trees were hit.

With the Blister Rust rampaging the forests it didn't take long for the U.S. Government to respond. Research began and it was found that Blister Rust had an intermediate host: Ribes, the current/gooseberry family. It was discovered that the Rust's life cycle went from Pine to Ribes, with a spore dispersal distance up to 100 miles, and then from Ribes to Pine with spores spreading for only up to a mile.

So the answer appeared easy: To save the pines, eradicate the Ribes! A program was initiated and in 1918, the war on Ribes began. In 1932, a crew of 12,000 CCC workers hand-pulled over 48 million plants. By 1934 the crew grew to 20,000 strong. Bulldozers and chemical sprays were also used. The battle continued until it became cost prohibitive and the program tapered dramatically. By 1959 over $100 million had been spent on the eradication of Ribes.

For the East Coast, the work proved fruitful and the disease was kept in check; the Eastern White Pine has successfully returned. But the Western States weren't so lucky. After trying extensive control methods it became evident that the Blister Rust was here to stay. Compiled with high costs, most eradication programs were discontinued by the early seventies. The five-needle pines were left to meet their fate...

Although this paints a pretty dismal picture, there is some hope. Current research is showing that some surviving pines have built up their own internal resistance and are creating a new generation of blister rust resistant trees. Replanting is already occurring. So perhaps with a bit of luck and a lot of optimism, the pines will survive and our depleted forests will be replenished.

Roy Simpson

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