By George! - A Blog!

There is an argument that states that a parasite, living on its host, would be crazy to kill the host and deny itself a source of food.  I used to accept that argument in the case of parasitic mistletoe but now I don’t think its a good argument, especially after a series of dry years. when the trees are under a water stress

 I see more mistletoe these days and it’s hard to understand why it is so if the trees have lost their vigor.  There are still a number of birds that eat the berries and spread the seed and clean their sticky beaks on the rough bark of our native trees.  There are still plenty of native trees and it’s hard to find dead ones in spite of our dry years. Nevertheless, those surviving trees are looking more miserable than they need to be and the mistletoe looks so strong and vigorous.

The moisture that the parasite needs comes from the host tree and if that tree is not supplied with water, either by rain or by irrigation, it’s sure to suffer.  I’m joining the people who remove the pest.

Simply pulling off the great green gobs from a tree’s trunk helps the tree but it doesn’t kill the pest.  It will sprout out again because it roots are all through the trunk.  If you are able to do this on a reglar basis you will help to preserve the health of the tree.  If you break off clusters up in the branches you will be giving more help, especially if it’s a cluster that has just started–looking like a bird’s nest, for example.  If it’s a more robust growth coming out of a branch it’s better to cut out the parasite with a piece of the branch.  Try to do this without upsetting the balance of the tree’s appearance but even if this is not possible you’ll be doing more good than harm because you’ll be preventing the mistletoe’s growing through the branch system and into the trunk itself.

There’s no chemical that will kill mistletoe without affecting the host tree.  Any systemic chemical will also affect the host tree because the pest and the host conducting systems are so intertwined.  This means there is only one method of control–pulling off and cutting out.  You can suppress new growth on large branches and the trunk by wrapping black plastic to smother the shoots remaining in the wood of the tree.  When they start growing again they will be in the dark and unable to thrive without sunshine. A few people say this method will gather and hold heat from the sun so the trunk will suffer but if they stop to think they’ll discover that trees’ foliage usually shades the trunks.  Desert trees, such as mesquite, palo verde and acacias are untidy trees whose branches often weep down to the ground.

This time of  the year gives us a golden opportunity to help the trees.  At present the pest is obvious, whereas after the leaves come out we won’t be able to see the problem. All green things look alike up in the branches in mid-summer.