A common problem with peach trees presents itself in the form of dark spots and holes on the leaves. Because we have had questions about this particular issue, we wanted to explain what it is, how it happens and what can be done about it.
What Are the Spots on my Peach Tree Leaves?
If you have spots and holes on your peach leaves similar to what you see on the left, you are dealing with bacterial leaf spot, a disease that is not uncommon in peach trees. It is caused by a bacterium called xanthomonas pruni. In addition to the deformed leaves, bacterial leaf spot may also affect the fruit itself as well as accounting for smaller crops that normal. Bacterial leaf spot affects peaches, nectarines, apricots and plums.
How Does Bacterial Leaf Spot Occur?
Bacterial leaf spot happens when the bacterium overwinters itself in scars and lesions on the affected tree. In the spring when temperatures thaw, the bacteria reawaken and seep from the tree only to be carried by wind, rainfall, and even casual watering, infecting nearby trees. The xanthamonas pruni bacteria prefer warm, moist climates and can act quickly in the right conditions to infect a large number of trees in a small area.
What Can Be Done to Treat Bacterial Leaf Spot?
The bad news is that there is not a reliable control to prevent or treat bacterial leaf spot in peach trees. Suppression is sometimes possible with a copper sulfate spray in early spring when the blooms first begin to open. Again, this is just a suppressive measure and will not eliminate the bacteria altogether.
Removing affected limbs is one potential stopgap measure, but any remaining bacteria can and usually will begin the spread anew with the next rainfall.