By George! - A Blog!

Our desert trees have gone through a year of inadequate rainfall, which is something we cannot do anything about. That’s bad enough a handicap to good health. What we can see, now that the leaves have fallen off is a widespread scourge that we can do something about.  Those lumps of green that infest the branches are a parasite, stealing the juices of water and of nutrients in the tree itself.  They are very visible while the tree is leafless but when warm weather returns and the tree puts out fresh leaves we won’t see the mistletoe and we might forget them.  That would be unfortunate for the host, mesquite.

Where do mistletoes come from?   Birds bring them and the story goes like this.  Mistletoe is a dieacious plant, meaning that there are male plants and female plants, just as in dates and hollies.  The female plants bear berries and though they are small and insignificant, they carry a small seed nesting in a sticky juice. Birds know this, or they quickly find that the berries are difficult to eat so they wipe their beaks on branches of trees. This “cleansing of the beaks” often pushes the seed into crevices between the rough bark where it is safe and secure.  A little gentle rain or morning dew is all that the seed needs to start germinating.  The young root burrows into the bark and begins extracting moisture and nutrients from the tree and it stays there until it is quite a vigorous parasite.

You’d think that a parasite would be foolhardy to actually kill its host because that would mean the end of life for the parasite, but that is what happens.  In years when we get good rains the tree might not suffer very much but two years of inadequate rain puts a load of stress on the tree, and that’s where we are now.

The point is that we can easily see the mistletoe whereas when the leaves come out we won’t.  So, if we want to keep our desert vegetation, now is the time to take action.  Mistletoes can easily be pulled off, though the roots left in the tree will sprout again–and the green stuff will have to be pulled off again. Keep this up for a year or two and the pest will be defeated. Some landscapers wrap black plastic over the branch where the pest was and any sprouts rejoin this world in the dark and they die more quickly.  There are situations where the pest has lived off its host for several years and is thoroughly entrenched in the wood of the tree.  Then the remedy is to prune out a branch that is so heavily infested.  Hopefully this severe action will not you with a mutilated tree.  I have two large shade trees that were so badly infested that new mistletoe shoots burst through the bark lower down on the trunk and it became necessary to cut the trees almost to the ground in order to get rid of the pest.  The landscaper who did this work said that the trees would sprout again, clear of the pest–and indeed they did.  Both trees were serving a very useful shading of the house and the driveway.

When you pull off the pest, don’t leave it lying on the ground if it has little white berries.  Birds will find them and they’ll re-infest your vulnerable trees.  Put the stuff in the garbage to get it off your property