OVERTON — County extension agents are reporting that fire blight attacks on pear trees are early and unusually severe in East Texas this year.
Bob Armentrout, Polk County agent with the Texas Agricultural Extension Service, said fire blight damage is the worst he has seen in 15 years.
“We have pears which are so infected I can’t find a clean leaflet at all, he said. “I checked a Bradford pear which is about 11 years old, large and beautiful, except the entire canopy is disappearing.”
A mayhaw producer reported to Armentrout that fire blight is showing up on all his mayhaws, some worse than others.
“On the bad ones, he says he will probably lose the entire spur, fruit and all,” Armentrout said.
In neighboring Trinity County, agricultural agent James Alford reported getting calls from orchard owners “very early” this year.
In Texas, pear tree owners can expect to see some fire blight on pears and other species every year. During times when conditions are right, such as when extended cool, wet spring weather coincides with pear tree blooming, the severity of fire blight infection can reach epidemic proportions. The disease also attacks apple trees, quince, spiraea, hawthorne and as many as 70 other species.
The fact that an ornamental pear, such as Bradford, has been infected is a sign that this could be an unusually bad year for blight, according to Dr. George Philley, Extension plant pathologist.
Though it makes the tree unsightly, the disease will rarely kill an ornamental or other pear variety. Ornamental pear tree owners can expect their trees to bounce back later in the year.
In the spring, the disease usually first shows up as blossom blight. Infected blossoms become water-soaked and then turn dark brown. The disease then moves down the fruit stem, causing the area it infects to become water soaked and turn dark green. From the fruit stem, the disease migrates into the leaves of the blighted spur.
Twigs become dark green and oily looking when infected. Pear tree leaves and stems will eventually turn black, as if burned, hence the name “fire blight.” In contrast, the disease turns apple tree leaves and stems dark brown.
Other than variety selection, home gardeners have two means of controlling the disease: cultural and chemical. Cultural methods involve pruning the infected portion of the stem, four to six inches below the visible symptoms. Pruning shears should be disinfected in a 10 percent bleach solution to prevent spreading the disease to uninfected trees.
Philley warned excessive pruning can promote succulent growth that is highly susceptible to new infection. Excessive pruning can also cause the tree to become misshapen.
Several chemical and antibiotic controls exist for fire blight, but they are only effective if used during the bloom stage. A copper fungicide such as Kocide 101 or bordeaux mix should be applied during bloom at the shortest recommended intervals stated on the label. Another option is to use an antibiotic such as streptomycin sulfate. Neither the copper fungicides nor the streptomycin sulfate is toxic to bees. Philley emphasized that preventing early infection is critical to controlling fire blight.
“Once the bacterium that cause fire blight colonizes woody tissue, the only way to stop movement down a young stem or branch is to prune it out. If they treat before or after bloom, they’re just wasting their money and time,” Philley said.
Dry, hot weather will eventually slow disease development. Except for young specimens and highly susceptible varieties such as Bartlett, most trees will eventually recover.