By Sheri Bethard

Orange County Master Gardeners

This week I have received a number of emails and texts asking what the stuff is that is sticking out of their citrus trees is.  So, my article is regarding citrus borer insects. First let me say if you have green growth at the bottom of your tree, this is more than likely growth from the original rootstock your tree was grafted on to produce a quality tree. There are two common rootstocks used in Texas which are Flying Dragon and Trifoliate Orange. Neither one has a good tasting fruit if you are thinking about growing this tree out. If the growth is more than about 6 inches or so above the ground it is possible it could be from above the graft and your tree might be on a comeback.

Citrus trees serve as a host to a number of wood borer insects and controlling them is the main thing to save your tree. First you should identify which borer insect is attacking your tree. Their presence is seen by entry and exit holes in the tree bark or limbs. Based on the pictures I have seen, more than likely the borer that is attacking the citrus in our area is the locust borer. It produces a sawdust like material called frass where they have bored. If you see the adults flying around your tree this is a good sign they are about.

With the cold temperatures we had it has taken a toll on the citrus in our area.  The borers attack trees which are in declining states of health and ours were because of the 20+ degree temperatures we had for 3 or so days.

If borers only appear in one part of your tree, cut those areas off and discard or burn them to prevent further infestation. DO NOT PUT IN YOUR COMPOST PILES!! If all the limbs have not produced any new leaf growth, then you should cut that part back until you reach green wood.

There are many chemicals you can use for control of borers but Spinosad insecticides are normally recommended for use on citrus trees since it is naturally occurring (organic). Using insecticides can be difficult since the borers are protected underneath the bark. Be sure to follow the manufacturer’s instructions on how to use to successfully eradicate them.

As I stated, borers are usually a sign of an unhealthy tree. Normally they will attack dead or dying limbs or trees. So, the quicker you can remove the dead wood or trees in some cases this will help keep the borers from spreading to other nearby trees.