Iowa Derecho

Last month we all learned a new word here in Iowa. Derecho. 

Frankly, I have not heard that word before though I have lived in the area over a quarter of a century. I have heard many natives saying the same thing. It’s definitely an extremely rare phenomenon that I hope will not happen again for the next few hundred or thousand years over the sequoia hill. 

https://en.m.wikipedia.org/wiki/August_2020_Midwest_derecho

As it happened, my sequoia experiment was about 7-10 miles from the epicenter of the derecho. While the worst of the damage came from the winds above 120 mph (200 km/h) our area was mostly greeted with roughly 100 mph (160 km/h) straight wind. The epicenter or I guess, “epiline”, of the storm removed over half of all trees, we have lost probably around a quarter. The most affected trees in our area were those in 40-80 year old range. The oldest and largest trees over 100 years old withstood the wind with some large branches lost. My neighbor’s tree is a 100+ ft (30+ m) extremely thick (about 5ft/1.5m diameter) oak that had surprisingly little damage. Younger 2-15 year old trees were able to bend, sometimes nearly to the ground and survive because of that. One tree on my land got bent and stuck:

Anything in between 15 and 40 year old was a coin toss. I have about a dozen 50-80 year old oaks, hickories and elms  all around 80-100ft (~30m) tall. Only one such oak was completely destroyed snapping clean about half way along the trunk  and losing the entire crown. 

All trees lost some branches including massive major ones but overall we got “lucky” compared to the unbelievable scenes just down the road from us. Many areas have no intact trees above 20-30ft tall left, some completely torn out of the ground with immense root balls sticking up to the house roofs and some sheered off with mangled splintered trunks sticking out of the soil.

Amazingly, no losses to the sequoias or any other seedlings on my tree farm. Several cages were mangled by downed smaller trees and flying giant branches but after digging the seedlings from under the debris there was no significant damage to speak of to the trees themselves. 

One young spruce was removed from the ground along with its rootball by a branch that was dragged along its location but I stuck it back into the hole and it may still survive. Most potential damage is to the sequoia and other seedlings root balls as the trees were pressed against the ground practically 90 degrees from their normal orientation and then repeated many times over the 15-20 minute period of the storm. That action wiggled some of them out of the soil. I pressed them back into the ground and filled in a bit with some dirt and small leaves and debris that thickly covered the entire area. Now almost a month after the event I do not see any negative effects although I thought such a disturbance to the root system can’t be good to their wellbeing. But I have to say that the growth since the derecho continued unabated with some sequoias posting most excellent progress. This statement applies to the sequoias of all ages and varieties, regular green and the hardy blue ones. 

Another fairly unusual phenomenon in progress is a severe drought that’s going on in the area. The humidity levels were consistently much lower than normal. High humidity in late summer is associated with fungus growth on sequoias. Not this year. There are no visible signs of the fungus except a couple of suspected small spots. Not to give fungi any chance all sequoias were treated with chlorothalonil three times since the start of the season, last time yesterday. Most of the trees look very healthy.

This is not to say that there were no casualties this summer. Several sequoias, both from the last fall and this spring planting, perished for one reason or another. These reasons are not entirely understood as some just started turning brown, some turning yellow and almost white, some just desiccating and turning thinner till complete death. A few had a malformed growth on the top where needles start bending and thickening making them look like an ugly light green flower preventing the lead to continue upward growth. 

Some have died but some have overcame that condition and a new side branch was able to grow through this and start a new lead. A couple are still recovering from that condition. 

The year old and this year germinated seedlings in containers are doing reasonably well as well. The biggest problem with them is desiccation due to lack of rain and the high temperatures. I failed to water them in time several times and lost a few because of that as containers got very light. 

Speaking about watering, I have watered a few sequoias with very generous amount of water through the entire season. I could not do it to all sequoias but to one selected patch that was closest to the water faucet. Surprisingly two younger sequoias on that patch died but the rest grew extremely well. One in particular, of a green variety, is the healthiest sequoia with great shape that I have ever seen in my experiments or elsewhere in the natural habitat. It’s definitely the largest sequoia by volume at present, though not the tallest. Several hardy blue varieties are taller due to a healthy growth this season, but none look as full as this green one.