HORTICULTURE

Fireblight Pictures

I have received many requests for higher quality pictures of fireblight for use in the print media.  The pictures I post on the web are smaller, lower quality pictures which load into browsers fairly quickly.  Below are small thumbnails of larger high quality pictures. Click on the thumbnail to load the larger high quality pictures into your browser and then save them. Not all these pictures were taken in 2000.

If you are not looking for really big picture files go to Pictures of Fire blight Symptoms. There good pictures of fireblight there.

Most of the pictures of Gala below were all taken in 2000 in the same orchard.

Heavy Fireblight Infection of a High Density Planting of a Very Susceptible Variety

This 4 year Gala on M9 orchard is located in Northern Berrien county. The green tree located in the left row is a relatively resistant crabapple pollinizer. This picture was taken in early June of 2000, 2 weeks after a hail storm and onset of wide spread fireblight symptoms in the region. New shoots have been killed and the leaves have died giving the trees a brown appearance. Gala is very susceptible to fireblight and the M9 rootstock is also very susceptible to the bacterial pathogen Erwinia amylovora.

Picture of a single tree extensively damaged by fireblight

This is a single tree located in the orchard above showing the multiple infections affecting almost all the new shoots and loss of young wood. The rootstock at the base of the tree looks like it is oozing in this picture but a closer examination of the tree in July did not show ooze and that the markings are only furrows in the bark.

Close-up of new growth near the edge of the infection margin

Close-up of the fireblight canker margin moving down the central leader to the tree above. New shoots are growing out of healthy tissue. Darker tissue above the new shoots mark the extent of the cankers in early June.

The same orchard in late July

The same orchard, same rows in July. By now the disease has run its course and there is little new development.  Dead leaves and shoots are now black giving the trees a burned appearance hence the name fireblight. Not visible in this picture is that many of these trees had put out extensive regrowth from unaffected tissues in between cankers on the limbs and trunks. At this point in time we all had hope that the orchard would recover, but almost all the graft unions showed oozing indicating that the infection had reached the rootstock and the susceptible rootstock was infected.

An individual tree in July

This view shows the first tree in the left row of the picture above. Note the extensive death of young shoots earlier in the year and regrowth of new shoots from the interior part of the tree. The rootstock of this tree is oozing indicating that it is infected.  This tree will probably die this fall or fail to leaf out in the Spring.

Rootstock blight

Oozing from the rootstock graft union of the tree above indicates that this tree will die.

Resistance crabapple tree with fireblight

A crabapple pollinizer in Berrien County Gala orchard.  This picture was taken in late July.  The crabapple scion is resistant to fireblight but the M9 rootstock is not.   I noticed the upper part of this tree was pale and discolored. In this case the rootstock is infected with fire blight as indicted by ooze at the graft union near the ground.

Rootstock blight on crabapple

A close-up of the graft union of the crabapple tree above. Sometimes the fire blight infection can travel symptomlessly from the scion to the rootstock.  In this case, dead shoots can be seen that are coming from the rootstock.  The infection may have come in through these shoots, or the shoots may have been killed by an herbicide and the bacteria responsible for the infection came down through the trunk from an infection higher in the tree without symptoms in between.

Other pictures from 2000

3-year old Gala Orchard in Central Van Buren County. This orchard is a total loss, most of the trees exhibited oozing from the graft unions. This orchard is much more severely affected than the one in Berrien Country because the trees are younger and smaller.  Fire blight moves quickly through one and 2-year-old wood but slows down in older wood making older trees more likely to survive.

Oozing graft union of a 3 year-old Gala on M9 from the orchard pictured above.

A 12-year-old Gala on M26 root.   This planting was abandoned because of poor apple prices and these trees received no pruning or fertilizer for the previous 3 years.

A close-up of the middle of the central leader in the tree above.  This view shows ooze from cankers above and in the picture running down the trunk of the tree.  This ooze contains millions of bacteria and could cause continued spread of the disease if there was a hail storm in this orchard.  A dead branch is visible in the right center of the photo and the canker formed by fireblight is visible on the trunk at the base of the branch.  The bacteria will overwinter in the margins of this canker and begin to ooze next spring at about bloom time enabling the disease to spread to other trees and open flowers during bloom. Cankers should be removed during dormant pruning.

Other pictures of fireblight symptoms from other orchards and years.

Spur Blight or Blossom Blight

Often the initial fireblight symptom seen after bloom, spur blight is caused by the bacteria entering the flowers during bloom when rain washes the bacteria down into the base of the flower were it can enter through the nectar pores into the plant itself.  The bacteria kills the flower (blossom blight) and often the spur (spur blight). This is a picture taken several weeks after the onset of symptoms. On this tree the infection has killed several spurs and caused oozing at the base of the spurs.  Because of the age of the wood on this branch the canker has not moved far.  This canker has the potential to girdle the limb and cause the shoot to die. If this canker remains active it will spread fireblight in this orchard next year.

Shoot Blight

Shoot blight symptoms occur after blossom blight. The bacteria moves through the tree from the initial infection sites (flowers or damaged tissues from trauma).   Large numbers of bacteria cause the shoots to wilt and die. This results in the Shepherd's Crook symptom where the tip of the shoot wilts and curls downward. The infection moves down the limb killing tissue and new shoots as it goes. This view shows new and old shoot blight symptoms. This symptom is very common in the month after bloom while the tree is actively growing.  As shoot growth slows in the summer, the internal spread of the disease slows and shoot blight symptoms become rare.

Leaf Symptoms

Yellow orange leaves

This picture shows the color symptoms that are expressed when the shoots originate from a shoot that is girdled by a canker and the shoots above the canker die.  In summer and fall, whole trees may exhibit this color earlier than the normal fall color change indicating that the rootstock is infected and dying.

Fruit Infections

Mid season fruit infection

This fruit became infected in July as the shoot it was on died. In this case the fruit has dried out and there is no ooze.

Preharvest or late season fruit infection

This fruit was infected only a few weeks before harvest. Note the bacterial ooze on the fruit.

For more pictures of fire blight see Fire blight Symptoms. There lots of good pictures there also.

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First posted: August 23, 2000
Edited: October 24, 2002