Favorable weather conditions for pollination of the valley's surviving fruit crops may bring with them a hidden danger in a possible microbial infestation, experts say.
After a month of rain, the valley's orchards are finally drying out, bringing warmer conditions in the 60- to 70-degree range that have most apple and pear trees blooming. Those are two of the conditions necessary for the presence of fire blight.The bacterial infection also requires the presence of some moisture on the tree blossoms, something that could occur with even slight amounts of precipitation, said Tony Hatch, Utah State Extension Services fruit specialist.
Fire blight starts in the blossoms and progresses through older wood, Hatch said. "It kills the wood deep into the tree and prevents any nutrients and water from going elsewhere in the tree."
Previous infections hurt the valley's pear industry. Pears, as well as some apple varieties, are extremely susceptible to the blight during blooming, he said.
"At one time, the county used to be much more into the pear industry. However, there are other fruits that have taken its place in the fruit farming industry, and a lot of that can be attributed to fire blight."
One telltale sign of the infection is a burnt look around blossom clusters or near newer branches, he said. "It quite literally looks like someone has taken a blowtorch to those areas."
Also, the blight is sometimes followed by oozing or gumminess around the blossoms, distinguishing it from "blossom blast," another bacterial infestation more prevalent in moister climates.
Hatch recommends that farmers spray susceptible trees with streptomycin treatments for fire blight prevention. Farmers should treat trees every three to five days as long as all three blight conditions exist, he said.
"Ideally, they could go out and spray just after a light drizzle, but then the possibility exists that there might be a downpour. They shouldn't wait longer than 24 hours after a storm, though."
Fortunately for most farmers, with warm conditions, the trees may have all shed their blooms by the end of the month, thereby reducing the danger, Hatch said.
"Most trees are already in full bloom and have been pollinated, so they should be in good shape, at least as a harvest goes."
He said that apple and pear yields could be quite high this year, and some apple orchards could set some production records. However, the trees could still face some fire blight danger in newer twigs.
Such infections are still very serious, but after harvest season the infection usually does not affect older wood, Hatch said. He said farmers should continue treating areas they feel may be susceptible to the infection.