Connecting Greater Phoenix gardeners with information that helps put xeriscape principles into action.

Clean Pruning Tools for Healthy Plants

I just finished writing the Oleander Leaf Scorch (OLS) article.  Caused by the Xylella fastidiosa bacteria, OLS has been decimating the oleander population in Phoenix xeriscapes, especially in north central Phoenix. There’s no evidence that OLS spreads by unclean pruning tools, but it’s a good reminder–now that’s it’s pruning season–to thoroughly clean and disinfect your pruning tools each time you (or your landscaping crew) move to a new plant. 

Here’s what I do:  put isopropyl alcohol, commonly available in drugstores, into a spray bottle.  Thoroughly spray the tool, then wipe clean after about a minute.  Do this before moving on to a new plant.  At the end of the day, after cleaning your tools but before you put them away, spray each with a thin coat of WD-40.  That keeps all the parts clean and working properly. 

Cleaning pruning tools is a best practice that keeps your tools in good shape while reducing the spread of pathogens.

Oleander Leaf Scorch in Phoenix

Beginning stages of OLS

Progression of OLS

Progression of OLS

Progression of OLS

Advancing OLS




 If you have oleanders, take a minute to see if they have Oleander Leaf Scorch (OLS).  OLS is caused by a bacteria (Xylella fastidiosa), carried by the leafhopper species, which has been decimating oleanders throughout the Southwest. 

The insects block the flow of xylem (ie, water) within the plant causing leaves to turn yellow, brown, and then to die off.  It looks kind of like drought-stress, except that the yellowing starts on the leaf margins and works its way inward.  If watering the plant doesn’t help, then it’s probably OLS.  The symptoms become more pronounced as the weather warms, affecting both red- and white-flowered oleanders. 

The only cure for OLS is to remove them completely.  Cutting them down to the ground will result in seemingly healthy offshoots and may delay the need to remove them by one to five years.  But they will ultimately need to come out.  Read more about Oleander Leaf Scorch. 

The good news is that there are very good, low-water, and non-toxic alternatives to oleanders.  Hop Bush (Dodonaea viscosa) does really well in Phoenix.  While its flowers are not as showy as the oleander, it is an evergreen that can grow to 10-12′ for privacy.