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Chester County Press

As fly infestations increase, mushroom industry seeks solutions

12/14/2016 10:04AM ● By Richard Gaw
By Richard L. Gaw
Staff Writer

Growing Numbers, Growing Concern

It is a cold morning in the middle of December, and Chris Alonzo, the owner of Pietro Industries, opens the door to his mushroom growing operation in Kennett Township. Built in 2008, it's a massive, 24-room growing facility, but because it is designed in the style and colors of a traditional barn, it melds with the landscape rather than intrudes on it.
This is not by accident. As he escorts a visitor through the building, Alonzo walks with a quiet sense of accomplishment, and every time he talks about the business, he answers thoughtfully, careful not to tread too heavily on the big footprint of the industry he represents.  He is the third line in a three-generation family of mushroom growers dating back to 1938, and like so many others who make up Chester County's leading industry, Alonzo believes he is first a member of the community, and a businessman second.
The reason he is here, giving a tour of his growing facility, has much to do with the future of both.
Alonzo does not hide evidence of the phorid fly that affected his growing facility this year, but he also shows the painstaking measures his staff has taken to dramatically decrease their numbers. There are ten large bug zappers placed throughout the facility. Protective plastic sheeting and sticky paper rims surround every window. Detailed records that track the number of flies in each room are kept, every hour of every day.
As a worker carefully waters row after row of white mushrooms, Alonzo describes how each room is regularly steamed up to 150 degrees to sanitize the area of all flies.
“This year, I have seen an increase in the presence of the phorid fly, and the pressure of the phorid fly has not only been more intense, but also longer in duration,” Alonzo said. “Four years ago, we only saw it in September and October. Three years ago, we saw them for a little longer, and this year, we saw them from April to December. Their visibility is not only a higher intensity, but one that is more sustained.”
Alonzo is not alone. Over the past year, the local mushroom industry has been experiencing a rapid growth in the appearance of phorid flies -- tiny black flying specks that are attracted to the smell of mushroom compost and growing mycelium. They are getting inside the growing rooms through every possible opening and crack, and laying eggs in the substrate, casing layer, and on the mushrooms themselves. Always a nuisance, they are now a growing concern for every mushroom farmer who fears the worst: That the larvae that appears from the eggs five to 10 days after hatching may cause great damage to the mushrooms.
Although not known to be a health hazard to humans, the phorid fly is wreaking havoc on mushrooms. In addition to the yield losses that larvae cause, the mushrooms lose their marketable appearance because of the larvae that swarm on their surface. Larvae also enter fruit bodies, forming many passageways and holes, which makes the mushrooms unsuitable for use.
Normally, the flies increase during summer and fall, when a massive phorid fly reproduction and migration occurs. Now, however, that normal cycle has more than doubled.
In short, the arrival of the phorid fly to the industry is not new, but the exploding growth of their population in recent years is.
“We have seen an increase in the population of the phorids this year, and at some of our farms, it's been more than we've seen at any other time we could remember,” said Mike Pia, Sr., of Kaolin Mushroom Farms. “There has certainly been an impact on the crop. They haven't been as damaging as the impact of sciarid flies [which have a year-round presence at mushroom growing facilities], but the impact is there.
“We certainly would like to be rid of them,” he said. “There is some impact to our crop. It's not a devastating impact, but it's a reality.”
For an industry in Berks and Chester counties that is responsible for 64 percent of the mushrooms grown in the United States, addressing the problem of the phorid fly has become a vital concern.

Preventive measures

For years, mushroom growers all over the world had ready access to chemical pesticides like diazinon, an insecticide used in agriculture to control insects on fruit, vegetable, nut and field crops. Although it is still used agriculturally today, it was pulled off the shelves for residential use in 2004. Because of increasing consumer demand for reduced pesticides, the industry has been pushed to develop novel methods to keep the phorid fly away.
For many growers, keeping fly numbers at reasonable levels has had the same effect as plugging up a rushing dam with a few logs, but it's a start. In Chester County and beyond, growing tunnels are sealed to prevent adult migration in houses; cracks, joints and loading doors are sealed properly; mesh screens and filters have been inserted over vents and fans; organic substrate is removed regularly from production sites; stagnant water pools are removed; and staff members are constantly educated on enforcing these measures. 
At the end of the cultivation cycle, all larvae are destroyed through the steaming of compost and the growing rooms, as well as spent batches.
At Kaolin Mushroms, Pia, Sr., said that the company goes another step in helping to keep the phorid fly population down, by keeping the grass areas outside the growing rooms cut short.
“They're everywhere,” he said. “They're coming to our farms, and we do our best to exterminate or eliminate them.
“We are following every known practice of trying to deal with the flies, and keep them out of the growing rooms,” he added. “Whether it be the application of soap on the outside of the buildings every day, clear plastic on the doors sprayed with trap material that acts as a large fly paper, electronic bug zappers, keeping organic materials cleaned up as quickly as possible to eliminate those areas where they could potentially be attracted to.
“We honestly can't control everything in our areas, but we can do the best we can to keep the operations clean, and organic material and concentrated in certain areas, in order to eliminate of the attraction of the flies to the compost.”
“What we realized when we heard that our neighbors were seeing the same fly pressure that we were seeing is that we've been dealing with fies for 20, 30, 50 years,” Alonzo said. “This is not a new occurrence, and the only newness has been that for the past three or four years, the pressure has been greater.”

Cooperating with Neighbors

When mushroom phorid populations in the environment are very high, the swarming flies have been known to cluster in and around houses, especially in neighborhoods close to mushroom farming operations. These large clusters of flies cause concern and aggravation for homeowners.
News of the phorid fly reaching local residences first came to light in a complaint filed six years with New Garden Township by Lou Taylor, a resident of the Harrogate North community in Landenberg. It has been nearly two years since Taylor and others met with New Garden officials to address the problem in a public forum, and in that time, reports of phorid flies have spread from Harrogate North to Toughkenamon, West Grove, Avondale, Lincoln University, New London Township, Oxford and in Hockessin, Del. A chart being developed by Kennett Township supervisor Whitney Hoffman tracks the increasing phorid fly problem in the county.
Their stories have been well documented in the Chester County Press: Thanksgiving dinners being ruined by an invasion of flies. A seemingly endless vacuum brigade of residents pulling up phorid flies from their homes, only to have them reappear hours later. Instead of recipes for gingerbread and pumpkin pie, neighbors share ideas for various chemical concoctions.
In short, those affected by the phorid fly in their homes have galvanized. Currently, more than 200 residents belong to an online group known as the "Phorid Fly Community," a Facebook page.    Working with townships and Sen. Andy Dinniman's office, they have organized public forums where representatives from the mushroom industry are invited -- most recently at the Avondale Fire Company on Oct. 25. The meeting included included Pennsylvania Deputy Secretary Fred Starathmeyer, Jr., of the state Department of Agriculture; Dr. David Beyer, a professor at Penn State and one of the nation's leading experts on phorid fly eradication; and New Garden officials.
While the tone of the audience was generally one of cooperation with the mushroom industry, there was an undercurrent of frustration that seemed to blame the phorid fly problem on the mushroom industry. It's a perception that doesn't correspond with the work the industry has been doing to cooperate with residents, while doing all they can to find possible solutions.
“I think the mushroom industry in Chester County has a proven record of seeing their neighbors and recognizing that we are part of the community, and not a stand-alone business,” Pia, Sr. said. “A lot of what we do -- all of us as growers and business owners -- has to do with continuing to place ourselves in the best situation in terms of our impact on the community.
“At the core of this is a misconception that we caused this problem, and for whatever reason we're not fixing it, and that is not the case,” Pia, Sr. added. “I can understand the frustration. I understand the nuisances, when you're not in the industry and you feel the industry is causing the problem, and you feel that they can fix it and they're not doing it.
“It's in our DNA to be a part of the community,” Pia. Sr. added. “Every grower recognizes that they are part of a core of belief in the way we conduct business. There is an issue that is affecting the growers and the residents, and we don't look at it as their problem. We look at it as our problem. We may not be fully in control of the problem, so it's nothing that we can by choice can eliminate. We're doing our best, and I would hope that most people in the community recognize that we are doing our best, with all the powers that be.”

Long-term Solutions

Through the haze of the fly infestation, there are some potential solutions on the horizon, and many of them are coming from Penn State.
Beyer told the audience on Oct. 25 that he has spent the past four decades -- including the last 13 years at Penn State -- looking into identifying new, non-toxic chemicals that can be used to manipulate the behavior of the phorid flies to lower their numbers. He told the audience he was hopeful that continued research could someday lead to the use of non-toxic chemicals for mass trapping and the disruption of fly mating cycles.
While both the mushroom industry and those residents affected by the phorid fly await scientific solutions, help is on the way. Sen. Dinniman recently announced that the Pennsylvania Department of Agriculture recently approved $100,000 in research grant funding to study ways to control and combat the phorid fly infestation.
“These flies continue to be a serious issue for both residents and farmers in Chester County and I am committed to finding a solution,” said Dinniman, who serves on the Senate Agriculture and Rural Affairs Committee. “This grant funding is a step forward in working to find new ways to effectively control and combat these pests.”
The funding will go to the Penn State College of Agricultural Sciences to study the ecology and control of phorid fly infestations on mushroom farms and surrounding communities.
The grant funding was the result of a meeting Dinniman held earlier this year with residents of Harrogate North, leaders of other communities impacted by the flies, and experts from Penn State and the American Mushroom Institute’s (AMI) Integrated Pest Management Committee.
Meanwhile, the American Mushroom Institute, headquartered in Avondale, is exploring ways to bring both the community and the mushroom industry together in a spirit of cooperation.
“We are exploring ways to deal with the problem, to see if there could be a way to put together brochures or schedule a conference with local neighbors,” said Bev King, communications manager with the institute. “We're doing everything that we possibly can to work with the community and the industry to set up meetings. We have the avenue to bring all of those people together to get a solution to the problem.”
Alonzo said that information shared among the mushroom industry -- in this case, research into the potential control, mitigation and eradication of the phorid fly -- is light years from where it was several decades ago. Armed with better information, Alonzo said that he looks at the phorid fly problem as a challenge that will best be faced by the entire community.
“With the extra fly pressure, it will help all of us solve our problems,” he said. “We're working on this from an individual farm standpoint, from a research standpoint, and from a reaching-out-to-the community standpoint.
“I feel the frustration of these neighbors, and as soon as we learn something, we will be willing to share that information with the community we are a part of.”

This is the second in a series of four reports on the phorid fly in Chester County. In the third installment, the Chester County Press will report on what research scientists are finding in their work to help reduce or eliminate the insect from mushroom farms and nearby residences.
To contact Staff Writer Richard L. Gaw, e-mail


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