Blending landscape mulch with mushroom compost: a green solution to the artillery fungus problem.

With the increase of both commercial and residential development, beautifully maintained landscape mulch beds are increasingly in demand. At the same time, the popularity of landscape mulch has been an economic boon to the landscape mulch industry. However, the rising use of landscape mulch has also been associated with an increased incidence of a relatively new plague-the explosive artillery fungus, Sphaerobous sp.

The Problem

The public has become aware that artillery fungi are the cause of sticky tar-like spots that tenaciously and permanently affix themselves to the sides of buildings, houses and automobiles. When homes are bombarded by artillery fungus, owners turn to their insurance agents expecting compensation but the fungus is not covered by their policy.

Homeowners file costly lawsuits against landscape professionals when claims are denied. Since the explosive artillery fungi live in landscape mulch, homeowners think landscape professionals must somehow be responsible. Using a decade of research data and expertise as Professor of Plant Pathology at Penn State, Dr. Davis has successfully testified on behalf of landscape professionals under litigation from property owners whose homes have been shot with artillery fungi living in landscape mulch.

The Fungus

Artillery fungi have two entirely different life styles, having developed a very successful "dual ecology" survival strategy. They can survive as white rotting, wood-decay fungi on dead trees, branches, wood and bark. The fungus also can live on droppings of herbivores such as rabbits and deer. This is important, as it bears on how the artillery fungi arrive at a landscaping site, and relates to who is responsible for the artillery fungus problem.

Artillery fungi may already be present at a new job site, on dead trees, branches on the ground, rotten wood, or old mulch if the fungus is acting as a wood decay organism. On the other hand, the artillery fungi may already be present at the site on rabbit pellets or deer droppings. In either case, the existing artillery fungus can immediately infest new, clean applications of landscape mulch.

In addition, artillery fungus spores may be transported for short distances by the wind or by people from nearby infestations, or even on new plantings that may have spores stuck to their leaves from an infested nursery. Also, artillery fungi often colonize sawmill wastes, old wooden pallets, land-clearing material, and other pieces of waste wood as they are laying around. If these infected pieces of wood are shredded and used as landscape mulch, the resultant mulch is infested. So, artillery fungus may already be in the mulch when the applicator receives it.

The question of responsibility for a current artillery fungus infestation at a commercial property or residence is not easy to determine. As Dr. Davis has testified, it is usually impossible to pinpoint the original source of the fungus, even if the history of the mulch is known.

Mushroom Compost

Mushroom compost is the leftover growing material (substrate) on which mushrooms are grown. Since each mushroom crop requires new substrate, the mushroom house is cleaned out after the final harvest of each mushroom crop. Over 700,000 cubic yards of mushroom compost are produced each year in Pennsylvania alone. This material is not used again to grow mushrooms and must be recycled. The compost is pasteurized (by steaming), removing most potential pathogens and weed seeds. If used immediately this clean compost is considered "fresh;" if allowed to weather, or age, it is considered "aged" mushroom compost. One must be aware that aged compost, if stored improperly, may contain weed seeds, just as does improperly stored topsoil. Fresh compost, on the other hand, contains few, if any, weed seeds.

Penn State Research

Penn State researchers wondered if this byproduct of mushroom production might prove to be an environmentally friendly solution to combating artillery fungi in both residential and commercial applications. Early research at Penn State revealed that aged (1-2 years old) mushroom compost, when blended at 40 percent or greater ratio (by volume) into landscape mulch, was effective in suppressing artillery fungus speculation. Also, they found that mushroom compost appeared to suppress other undesirable fungi, while providing some plant nutrients (1:1:1, N:P:K), increasing moisture holding capacity, and adding organic material to the soil as the compost breaks down.

Therefore, the researchers concluded that mushroom compost might, be a potentially valuable, "environmentally friendly" and "green" mulch amendment. Since early research had shown that blending aged mushroom compost into landscape mulch resulted in a significant suppression of artillery fungi, the team wondered if fresh mushroom compost in the blends would work as well. It takes time and money to age mushroom compost, so it seemed logical to evaluate the ability of fresh mushroom compost (right out of the mushroom house) to fight artillery fungi, thereby producing an economically viable, green alternative for mushroom growers, lands-capers and homeowners in the fight against artillery fungi.

Research plots were established at the Penn State Berks Campus (Reading, PA) to study the possibilities of using fresh mushroom compost. The most recent data (collected November 2007 and May 2008) are preliminary, but are very promising. These data continue to show that landscape mulch blended with 40 percent fresh mushroom compost is also efficient, as was previously shown with aged compost, in suppressing artillery fungi. Therefore, the three authors are currently conducting a project geared to bring together landscape personnel, mulch producers/ applicators, and mushroom industry partners to participate in needs assessment and marketing research for a blended compost-mulch product. The goal is to create a plan to facilitate the use of fresh mushroom compost blended into landscape mulch at a 40 percent ratio, and to identify and address perceived obstacles to use of the blended product.

On-Site Blending Project

Needs assessment data indicates that mulch producers perceive unknown factors that raise concerns about using mushroom compost. To identify the factors, and to alleviate concerns, the authors produced a "Mushroom compost & artillery fungus fact sheet," printed here and available to download from the mushroom compost Web site, www.mushroomcompost.org

Since the ability to view a commercial site was a common denominator among concerns, partners sought to complete an on-site blending prototype in 2008 using the recommended ratio of 40 percent mushroom compost blended into common landscape mulch. Laurel Valley Soils, Giorgi Mushroom Co. and Hy-Tech Mushroom Compost offered to partner by donating and delivering fresh mushroom compost for the project. Gloria Day, Pretty Dirty Ladies, Inc, had a customer site in West Chester, PA, that had been bombarded by the artillery fungus. Day was anxious to try the compost-mulch blend in what she termed, "a trend-setting application." Cordon Eadie Associates Landscape and Design offered to partner in the project by supplying a blending pad, landscape mulch and by physically mixing the blend.

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On June 18, 2008 the product of months of research and partnering was realized. Laurel Valley Soils donated and delivered fresh mushroom compost to a blending pad at Gordon Eadie Associates. The mushroom compost was blended into landscape mulch donated by Gordon Eadie at a ratio of 40 percent mushroom compost to 60 percent landscape mulch. The first commercial on-site blending of mushroom compost and landscape mulch had been completed.

Ten yards were mixed and ready to go in 20 minutes. The participants were impressed by the ease and speed of blending. The elaborate mixing processes usually associated with blending mulches do not apply when blending landscape mulch with mushroom compost. Buckets of mushroom compost and landscape mulch were mixed by alternating additions using a front-end loader. The blend was created by using the bucket of the front-end loader to spread each addition.

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A nicely blended product was produced. The participants noted that additional blending would naturally occur while loading and emptying the truck and during the application process. Thus, by time of application at a job site, the blend is thoroughly mixed.

The compost-mulch blend was then transported to the residential site in West Chester, PA where Pretty Dirty Ladies, Inc. applied the blended mulch. "This site had artillery fungus and poor soil, so I was anxious to apply the blend," said Day. "Mushroom compost is an excellent organic soil amendment so I was able to provide my client with an organic solution to combat artillery fungus, nutrient enrichment of the soil, and a dark, deep, rich color in her landscape mulch without compromising by using dyed mulch and chemicals. And my client is thrilled. She loves the way her beds look and we are both anxious to see that the artillery fungus problem will be solved. Honestly, the look of the mushroom compost blended in landscape mulch is the look every contractor and homeowner is looking for. I'd like to use this blend more often."

Gordon Eadie Associates, Pretty Dirty Ladies, Inc., the Southeastern PA mushroom compost suppliers and the authors will continue to monitor this first on-site application of mushroom compost and landscape mulch.

Summary

The researchers facilitated the first commercial blending of mushroom compost with landscape mulch and facilitated what every landscape professional was looking for--an on-site, commercial application. They also determined, identified and supplied answers to hesitations about blending mushroom compost into landscape mulch.

In this green market of environmental and cost-conscious consumers, blending fresh mushroom compost with landscape mulch offers many valuable benefits. This economic and green solution to pesky artillery fungi simultaneously adds plant nutrients to landscaped beds, reduces the need to fertilize, and increases the health of the soil and landscape plants. Healthy plants in beautifully mulched beds make happy customers, another benefit mushroom compost brings to landscape professionals.

For additional information on artillery fungi, visit Dr. Davis' Web page at: http://www.personal.psu.edu/faculty/d/d/ddd2/

PDA Funds Artilery Fungus Brochure

During the past three years, the SMS/Mushroom Compost Research Committee of AMI received grants from the Pennsylvania Department of Agriculture to discover the beneficial uses of Mushroom Compost. The Committee worked with Drs. Davis and Fidanza to produce the brochure, Using Mushroom Compost to Prevent Artillery Fungus. Three other brochures have been produced with funds from the grant including using mushroom compost on grass hay fields and for corn crops, as well as landscaping and lawn applications. Copies are available by calling the AMI Avon-dale office, 610-268/7483 or by visiting the Web site, www.mushroomcompost.org

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RELATED ARTICLE: Artillery Fungus

Fact Sheet

Q: What is the artillery fungus?

A: The artillery fungus is a wood-decay fungus that lives in wet landscape mulch. It produces a fruiting body that orients toward bright surfaces, such as light-colored houses or even parked cars in mulched parking lots. The artillery fungus then shoots black, sticky spore masses towards the light or reflected light. Spores can be windblown as high as the second story of a house. The spores stick to their target, remaining almost impossible to remove without leaving a stain, and look like splattered tar.

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The artillery fungus has become a serious problem in recent years, especially on sides of houses next to foundation landscape mulch. Dr. Donald Davis and Dr. Michael Fidanza at Penn State have been working on various solutions to combat this problem. One of their more recent findings has been that adding fresh mushroom compost to landscape mulch will suppress the artillery fungus.

Q: What, specifically, have the Penn State researchers found?

A: Drs. Davis and Fidanza have found that fresh mushroom compost successfully suppresses artillery fungus when a landscape mulch blend consists of [greater than or equal to] 40% fresh mushroom compost. Mushroom compost most likely is promoting beneficial microbes that compete against the artillery fungus.

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Q: Are there any commercial mulch producers offering such a blended product?

A: On June 18,2008 the first commercial on-site blending of mushroom compost and landscape mulch was completed. A 40% mushroom com post/landscape mulch blend was then transported to a residential site in West Chester, PA, where Gloria Day, owner-operator of Pretty Ditty Ladies Inc., Garden Design & Maintenance, applied the blend to combat a serious artillery fungus problem.

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Q: Are there any commercial mulch producers offering such a blended product?

A: On June 18, 2008 the first commercial on-site blending of mushroom compost and landscape mulch was completed. A 40% mushroom com-post/landscape mulch blend was then transported to a residential site in West Chester, PA, where Gloria Day, owner-operator of Pretty Dirty Ladies Inc., Garden Design & Maintenance, applied the blend to combat a serious artillery fungus problem.

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Q: Are there other benefits to adding mushroom compost to landscape mulch?

A: Mushroom compost is an excellent organic soil amendment, adding plant nutrients, beneficial microbes, and providing soil moisture retention. It can be blended with mulch at various rates, but if at least 40% mushroom compost is used, you will get the added benefit of artillery fungus suppression, even if you are adding mushroom compost for other reasons.

Q: Along this line, does adding mushroom compost to landscape mulch change the available nutrients to plants?

A: Adding mushroom compost contributes plant nutrients (approximately 1:1:1 N:P:K). Mushroom compost is recognized by the Pennsylvania Department of Agriculture as a registered fertilizer.

Q: Does Mushroom Compost smell? How about when it's hot?

A: You may notice an earthiness at time of installation which quickly disappears after installation.

Q: Is blended mulch affected by weather conditions?

A: Mushroom compost retains its appearance, holds moisture during drought, and filters water during heavy rains. In the long haul, mushroom compost will biodegrade and improve the health and organic quality of landscaped beds.

Q: My contractor wants to know what impact the blend will have on his equipment; especially at high concentrations of mushroom compost.

A: Your contractor may have been using aged mushroom compost, which can have a higher moisture content than fresh mushroom compost. The added moisture in aged mushroom compost may cause it to stick in trucks and buckets, so fresh mushroom compost may be more convenient to use.

Additionally, elaborate mixing processes associated with blending mulches do not apply when blending landscape mulch with mushroom compost. The blending that took place on June 18, 2008 was done with a front end loader. Buckets of mushroom compost and landscape mulch were alternately mixed and blended using the bucket of the front end loader. During transportation and application, further blending naturally occurred. Depending on the location and size of the site, blending may be done on site.

Q: Does mushroom compost blended with landscape mulch deteriorate or decompose faster than landscape mulch without mushroom compost?

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A: The answer may depend on the percentage of mushroom compost being blended, as well as the age of the mushroom compost. Over time mushroom compost will decompose and improve soil quality and plant health.

If the mushroom compost in your blend deteriorates at a faster rate than the blended mulch, an on-site addition of fresh mushroom compost, or a regularly scheduled application of mushroom compost/landscape mulch blend will continue to suppress the artillery fungus while naturally beautifying your beds.

Q: What is the color of mushroom compost? Will it fade?

A: Mushroom compost is brown to black. The blended color will depend on age of mushroom compost, type of mulch and percentage of the blend. Generally speaking, mushroom compost adds an attractive, rich earthy tone to landscaped beds.

Q: What about pH and salts?

A: Published Penn State research data using 30 random samples of mushroom compost has shown an average pH of 6.62. The salts in mushroom compost are actually nutrient salts, which are made available to plants through watering or rainfall.

Q: Will mushroom compost blended in my mulch harm my plants and flowers?

A: No, as a matter of fact, a mushroom com post/landscape mulch blend is highly beneficial to your plants and flowers. Mushroom compost is a made of predominantly organic materials that can enhance the health of your landscaped beds.

By adding mushroom compost to your landscape mulch, the organic quality of landscaped bed soils is improved, adding and promoting beneficial microbes while controlling artillery fungus and other bothersome surface fungi.

Q: Can I still use additional fertilizer on my plants and shrubs?

A: Always seek the advice of your landscape professional since soils, mulch, plant material and currently used applications must be considered.

Q: Has anybody done a sizeable installation?

A: Gloria Day, owner of Pretty Dirty Ladies, Inc., Garden and Landscape Design & Maintenance, recently applied a 40 percent compost/mulch blend at a residential site in West Chester, PA. The residence has been plagued with the artillery fungus, and was treated with six cubic yards of the blend.

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