Be Proactive to Ward Off Armillaria Root Rot

Be Proactive to Ward Off Armillaria Root Rot

Recently, an Extension Agent in the Florida Panhandle received a picture of some mushrooms popping up in a client’s garden.  These particular mushrooms were in a spot where leftover mushroom compost had been dumped.  The compost was previously used to grow oyster mushrooms and the client was hopeful that she had more oyster mushrooms growing in her yard.  Unfortunately, the lab results came back stating the mushrooms in question were Armillaria spp.

Armillaria spp.

Armillaria spp. in the garden. Photo Credit: University of Florida/IFAS Extension.

Armillaria spp. cause root rot of trees and shrubs throughout the world.  The fungus infects the roots and bases of trees, causing them to rot and eventually die.  Some species of Armillaria are primary pathogens that attack and kill plants, but most are opportunistic pathogens that are attracted to unhealthy or stressed plants.  Fruiting structures of the fungi can be recognized by the clusters of yellow to brown-colored mushrooms that emerge during wet conditions.  However, the mushroom caps sometimes never form and the plant material needs to be inspected more thoroughly to find the disease culprit.  Infected plants may have wilted branches, branch dieback, and stunted growth and should be removed and replaced with resistant species.

White mycelial fan under the bark of a root.

White mycelial fan under the bark of a root infected with Armillaria tabescens. Photo Credit: Ed Barnard

Management – The best method for controlling Armillaria root rot is with proper plant installation and maintenance.  Planting plant material at the proper depth will allow the roots to breathe and reduce the opportunity for the roots to rot.  Pruning tools should be sanitized between plant material.  Proper irrigation and fertilization will also reduce the risk of plant disease and root rot.  Lastly, you can choose to plant a diverse landscape with resistant species.

For more information on Armillaria root rot and a comprehensive list of resistant species, please view the EDIS publication:  Armillaria Root Rot

Healthy and Delicious, Oyster Mushrooms Can be Grown at Home

Healthy and Delicious, Oyster Mushrooms Can be Grown at Home

Following basic instructions, grow oyster mushrooms using sterilized straw, a plastic bag, oyster mushroom spawn, and water. Photo by Sunny Liao.

Oyster mushrooms (Pleurotus ostreatus) – which have nothing to do with oysters besides their similar shape – are some of the most delicate, subtlety flavored, and easiest to prepare mushrooms of the culinary world.

They can easily be fried, stir-fried, or braised within a matter of minutes in broths, vinegar, wines, and sauces; or added to soups, stuffed, or mixed with chopped garlic. Other mushrooms, such as shiitake, are sturdier and impart a meatier flavor and texture to a dish. Oyster mushrooms, especially those lighter in color, pair well with seafood or a white meat. Highly perishable, you will want to freeze oyster mushrooms after sautéing with butter or oil to preserve, or dehydrate them to enjoy at a later date.

In addition to being an easy mushroom to prepare, oyster mushrooms are a great source of fiber, protein, and many vitamins and minerals, as well as an excellent source of the antioxidant ergothioneine.

Oyster mushrooms can come in many shades, from cream-colored, to gray, golden, tan, and brown. Their white colored gills, when present, extend from beneath the cap down to their very short stems. They are often described as smelling slightly like licorice and can grow up to about nine inches, but are best consumed young when tender and mild.

Oyster mushrooms grow in many subtropical and temperate environments, commonly found in nature growing in layers, decomposing the wood of dying hardwood trees. This decomposition benefits the ecosystem, as the mushrooms return nutrients and minerals back into the soil.

Interestingly, oyster mushrooms are one of the few known carnivorous mushrooms. The mycelia of the fungi can consume and digest nematodes, which is how it is thought the oyster mushrooms acquire nitrogen.

Arguably one of the best qualities of oyster mushrooms are the ease to which they can be cultivated at home. Using sterilized straw, a plastic bag, oyster mushroom spawn, water, and following basic instructions, oyster mushroom can be produced in as little as two weeks!

You can learn all about oyster mushroom production on the Penn State Extension page: Cultivation of Oyster Mushrooms (

Once you have the materials gathered, follow this guide, developed by UF/IFAS Suwannee County Extension, to prepare oyster mushrooms bags at home: Preparation of Oyster Mushroom Bags (

As well as being healthy and delicious, oyster mushroom cultivation is fun, and just needs a small amount of space and effort!


Grow Shiitake Mushrooms in Your Backyard

Grow Shiitake Mushrooms in Your Backyard

Shiitake mushrooms growing from an oak log. Photo by Stephen Hight.

Shiitake mushrooms growing from an oak log. Photo by Stephen Hight, USDA

Growing up, I was never too fond of mushrooms. To me, their only purpose was to ruin a perfectly good pizza. As I got older, I started to warm up slightly toward raw button mushrooms in salads – with enough dressing, that is. But it wasn’t until I experienced my first taste of fresh shiitake mushrooms (Lentinula edodes) – introduced to me sautéed in butter – that I truly began to understand their intrigue. Their rich, almost smoky flavor, could transform any dish into something spectacular.

It was with the shiitakes, locally grown on a small Panhandle farm, that I finally developed my love for mushrooms. They could be added to so many dishes – simmered alongside chopped garlic, or in broth, a reduction of wine, or cream. Toss shiitakes with pasta, add in lieu of meat in a creamy risotto, or use them to enrich a soup or quiche.

I learned that shiitake mushrooms are not only delicious, but they are packed with nutrition, including fiber, protein, multiple vitamins, calcium, as well as an excellent source of antioxidants. But what I really found fascinating is how shiitake mushrooms are cultivated.

When the shiitakes are ready to fruit, arrange the logs so that the mushrooms can easily be harvested. Photo by Stephen Hight.

When the shiitakes are ready to fruit, arrange the logs so that the mushrooms can easily be harvested. Photo by Stephen Hight, USDA

To understand their production, you must first understand that mushrooms are merely the fruiting body, or sexual organs, of the fungi. Mycelia, which is the vegetative portion of the fungi, colonize logs and only form spore containing mushrooms when they are ready to reproduce. The Florida Panhandle is an excellent location to grow shiitake mushrooms, as they strongly prefer to grow on oak tree logs, such as laurel oaks, which is a hardwood species native to our area.

The logs must be fresh to avoid colonization by unwanted fungi, so producers must first cut down oak trees during fall or winter, when the trees have large amounts of stored carbohydrates. It is important to do this sustainably, ideally as part of a forest thinning. The trees should be about three to eight inches in diameter and should be cut to about four-foot lengths.

The next step is to inoculate the logs with shiitake spawn. You can purchase shiitake spawn as either plugs or sawdust form. It is important to get a strain that does well in our climate, so make sure to do some research, such as learning about strains through the North American Mycological Association.

To inoculate, drill holes into the logs and insert the spawn with a plunger, a hammer, or a turkey baster, depending on the form of spawn. The holes should then be coated with hot wax to protect the spawn from drying out and from becoming contaminated. The logs then incubate under shade with proper moisture and aeration for about six to 18 months, giving the mycelia time to colonize the log, which includes digesting decomposing organic material to absorb nutrients.

The mycelia will fruit for about a week, and will then need a rest period of eight to 12 weeks before fruiting again. Logs fruit for about four years, but are typically more productive in the second and third year during the spring or fall. Harvest the mushrooms daily by cutting them at the base, and place in a box and refrigerate until use. By immersing the logs in cold water or chilling in cold storage, you can encourage the logs to fruit, but this process may make your logs less productive over time. When the bark begins to slough off, production will slow down and eventually stop.

For more information on growing shiitake mushrooms, visit the UF/IFAS Small Farms Mushroom Production website.