Toyon Can Develop Fireblight Since it is in the Rose Family

Q. Does this look like fireblight disease to you on established toyon? Toyon is in the rose family of plants.

Toyon can catch fireblight bacterial disease in the spring and summer months.

A. Toyon is a California native plant in the rose family and related to Photinia. Both plants are susceptible to fireblight. When the plant is dead it can be hard to say. Sometimes susceptible plants only lose their flowers and sometimes the entire plant dies. With prolonged wet weather this disease can be vicious. Sometimes plants “linger” with this disease, and it can lie dormant until cooler and particularly wet weather.

Fireblight bacterial disease on new spring growth.

            Look for bacterial “ooze” coming from wounds. This “ooze” are wet spots on tree limbs or the trunk. During wet weather this ooze may attract insects. Observing this plant can be a good way to know otherwise you have to send it to a plant pathologist and know for sure. Best way, when in doubt, is to assume its fireblight and remove it and get the dead plant off the property before it has a chance to spread. Be sure to sterilize any pruning equipment when you are finished.

Fireblight on Asian pear in early summer

Fireblight Causes Problems with Fruit Trees if Missed Earlier

 Q. I came back from vacation and my ‘Gala’ apple tree branch was dead.  The tree also has some black spotting under the bark. I'm hoping it's not damage from fire blight. 

Both pictures are fire blight in 'Gala' apple tree with an older infection. As this reader suggested, the earlier symptoms were not noticed and the bacterial disease has now invaded the trunk. Most likely the trees will either die or may serve as a host for further infection of trees. 

A.  I looked at the picture you sent of your fruit tree, and it looks like older fire blight disease that escaped earlier detection and is now in the trunk of your tree.

Fire blight is a serious disease that is highly contagious for many apples. It’s more damaging to some apples like ‘Pink Lady’ than others such as your ‘Gala’.  It’s particularly damaging to all Asian pears.  It can be damaging to some European pears, like ‘Bartlett’ and others, such as ‘Keiffer’, it doesn’t seem to affect much here.

This is fire blight disease on a recently planted 'Bartlett' pear. Sometimes this disease can come in on nursery plants from "dirty" growers.

It is damaging to some ornamentals like pyracantha and some cotoneasters in the rose family. The varieties of these plants may show differences. It just depends on the genetics of the plant combined with the genetics of the disease.

When I saw this disease in the spring it was heavily into Asian pears, some European pears and many apples and quince. What gave it away then was the early spring growth, which was black, hooked and had the presence of sap.

Fire Blight control is normally through removal of the infected limbs 10 to 12 inches below where the infection is seen.

What gave it away to me now are the dark cankers (black spotting) on the trunks of your trees and also the presence of sap.  The “sap” is what is contagious and can cause it to spread.  The dark cankers are probably from earlier fireblight infestations. Once this particular disease gets into the trunk the tree usually dies.

If the tree continues to look bad or worsens, I would cut these trees down and get the pruning off of the property. You cannot use this wood for wood chips or anything near plants or it can reinfest susceptible plants.

Cool Wet Spring Perfect for Fireblight

Bacterial diseases like fireblight need openings to enter the susceptible plant. Flowers provide temporary openings and let this disease enter inside plants. So do fresh pruning cuts. Fireblight disease spreads from infected to uninfected plants through these openings. Rainy and windy weather helps spread this disease when flowers are open. Honeybees are suspected to spread this disease as well by visiting these flowers.

Cool, rainy weather when pear and apple are in bloom, is perfect weather for fireblight disease. Fireblight is a very aggressive and dangerous plant disease that shows up as new infections in about May in Asian Pear, European pear like Bartlett and some apples. It can be a major problem on Quince as well.

This is why the first evidence of fire blight disease is usually seen by the blackening of the flowers in late spring. From here it can spread into branches and cause severe problems.

            But the disease problem, although unseen, can begin now. The point of entry for this disease into susceptible plants are the open flowers and fresh pruning cuts. Open flowers and fresh pruning cuts provide “fresh wounds” or points for this disease to enter inside the plant. Wind and rain are the usual culprits that spread the disease from plant to plant but even honeybees can be responsible.

Fireblight has spread from a flower or pruning cut and caused more dieback.

            If this disease is seen early enough (usually in late April or May) it can be eliminated easily with a few snips of a sanitized hand pruner, eliminating the infection. But the hand pruner must be disinfected between each cut on the tree or the disease can be spread on the hand pruners through each cut.

Classic textbook dieback and progression of fireblight disease

            There is some disagreement about what to use to disinfect hand pruners but chlorine bleach seems to be the favorite among orchardists. Heat from the open flame a cigarette lighter also seems to work. Some people suggest alcohol and others suggest household cleaners like Pine-Sol.

            Plants that were infected in previous years will show evidence of this disease when new growth occurs in the next couple of weeks. As the name suggests, this damage resembles the black from fire damage. This can be confusing because any damage to pear leaves can turn black. If you are unsure, send me a picture.

            We have had a surge in this bacterial disease over the past few gardening seasons because of our cool wet springs. I will post more pictures of this disease from past years on my Internet blog, Xtremehorticulture of the Desert.

Blackened Dead Leaves May Be A Really Bad Disease Problem from Last Year

Q. I planted a five-gallon pear tree about three springs ago and it seems pretty happy espaliered along my west-facing block wall, but a few new leaves on three of the branches have some kind of black rot on them. It has rotted away part of the leaf on some of them. Can you tell me what this disease is and whether and how to fight it?