CO-Horts Blog

Monday, June 1, 2020

And new studies say…

So hopefully many of you that can plant a tree have planted a tree.  But we are making different choices in the last few decades on which trees we chosen.  Do you think about what type of tree?  Does it have flowers, fruits, drops leaves?  I often get calls for plants that are low maintenance meaning that they don’t make a mess.  But we don’t find the forest messy and no one cleans up the leaves, fruit, and nuts and so on.  So we have moved as consumers to pick trees that don’t fruit or hold on to fruit (persistent fruit) which seems to make sense.  I personally have a Sensation boxelder in my backyard.  It is a boy tree, which means there are no seeds which means the boxelder bugs won’t be visiting to eat the seeds.  Those pesky seed bugs, like the elm seed bug that is so hated in Grand Junction have the nerve to seek refuge in our houses when it is too hot or too cold outside.  But who can blame them.  
Acer negundo, Boxelder, Male flowers, ipmimages

Luckily for us, some trees have flowers of different sexes on different trees.  This is called dioecious, two houses.  Where many trees have monoecious, meaning they have either sexes on one flower or both types of flowers on one tree, one house.  So over time, male trees have been chosen when possible to be used in the landscape nursery industry to prevent a mess.  I mean who wouldn’t want a cotton less cottonwood.  Unless you are an insect that eats the seed, or a bird that uses the fluff to line their nest.  Now there is new research that states because we are planting all these male trees, we have increased the pollen count.  That’s right it is the boy flowers that release the pollen to find the ovary of the flower to make seeds.  So it has increased allergies and pollution in a sense.  All choices have consequences.  Do you deal with the bugs and the seeds or fruit, or do you deal with increased hay fever and dirty cars and skies?
Pine pollen explosion,

Onto the next study.  I have never liked weeds.  It may have started when dad set me in the vegetable garden as a 11 year old with a big trashcan and told me to fill it.  When I got upset about it taking so long, he fluffed up the weeds and told me I was almost done.  Over the years, I have realized how fast weeds can take over the best gardens or natural areas, even doing things like changing the fire cycle in the West as is the case of downy brome, also known as cheatgrass.  I think cheatgrass is correct as it cheats the native plants by competing for water and nutrients and goes to seed ahead of most perennials as it is a winter annual.  That means it germinates and starts growing the previous late summer to fall, goes to town growing in early spring then by the time it gets hot it has gone to seed and dried up.  Hence the fire danger.  And then there are weeds that change the environment by bringing more salts to the top layer of the soil such as Salt Cedar otherwise known as Tamarisk.  

Russian Knapweed takeover, Steve Dewey, ipmimages
The salt cedar is often times followed by Russian knapweed, which puts out a chemical to prevent other plants from growing.  This is called allelopathic when a plant does this.  Walnut trees are a well-known tree that is allelopathic, so it can produce without competition.  But now, new research states that many of these non-native weeds actually kill the very microbes in our soil that support the plants that are living here.  That is scary.  So if you have more salt, weed chemicals and now the microbes are dead, maybe not all at once, but you can see the impact weeds have on our environment.  So please, get the weeds under control before they take over and ruin your soil.  And we wonder why it is so challenging to garden and landscape.  This makes me want to plant more native plants that were meant to grow in our soils.

Take care and get outside.

1 comment:

  1. Thank you - I hadn't been aware of some of this before (male trees and increased pollen, non native weeds killing soil microbes.
    Thank you for including photos.