By now, many of you know that I lost my precious puppy Justin Timberlake after he ate a Death Cap mushroom. This is a mushroom so deadly that half of one can kill an adult human. It doesn’t take much to kill a puppy. The horrible thing about the Death Cap is that, once ingested, it profoundly destroys the liver, even before symptoms are shown. I had Justin at the emergency vet within 18 hours of when I think he was exposed. By that point, his liver was so destroyed he was immediately hooked to machines. I had to let him go less than 48 hours after I think he ingested the mushroom as his organs were so damaged there was no chance he could survive.

Here’s the terrible thing. Although I’ve been reading the stories about the spike in Death Cap poisoning recently, I never in million years thought there was any chance of encountering it on my property. We’ve had two unusually wet winters in a row and that’s led to a spike in mushroom growth. Like all mushrooms, Death Cap needs a dark, damp, cool place to thrive. Although I’ve seen some mushrooms on our land in the midst of winter rains and only in some of the more forested parts of my land, for most of the Rancho, the hot relentless sun — which streams down nearly year round — would turn a mushroom to powder. As I was dropping off Justin urine’s sample to UC Davis in an attempt to get a definitive answer on whether he was exposed, I spoke to a mushroom expert. I asked him how a Death Cap could survive in my sun baked ecosystem which is often referred to as Oak and Chaparral. He said it couldn’t — except if there were a “conducive micro-climate”.

The Death Cap starts its life looking like a puffball. It then breaks through that caul and looks more toadstooly.

Let me pause to explain the concept of micro-climate. About the only thing I took away from the one viticulture course I took is that most of us misuse the term micro-climate. We use it to label a swath of areas like the foggy San Francisco Bay which is cooler than the surrounding California grasslands. For the true definition of micro-climate, you need to think smaller, as in really really micro. In viticulture, micro-climate refers to the conditions underneath one vine. A micro-climate is a small area where specific factors or often human manipulation change the climate conditions significantly from the areas immediately around it. We manipulate the micro-climate under our vines by the way we prune the green growth. In an extremely hot year — or for a grape that needs slightly cooler conditions than exist in the area — we let the green growth grow thicker, thus shading the grapes on that particular vine and keeping them cooler than they would be directly out from that cover. In parts of France where they don’t always get the heat they need to ripen grapes, farmers line the area under their vines with mulching of small stones that reflect heat back on the grapes, making a micro-climate that might be one degree warmer than the immediate surrounding area.

So how does this relate to Death Cap mushrooms? Well, Dwayne “The Rock” Johnson just lost a puppy to ingestion of Death Cap. In his backyard in blisteringly hot Los Angeles. The lawn is key, because, under normal circumstances, y0u couldn’t have one in LA. Clearly, there was heavy irrigation, probably some bushy shrubs and landscaping. Voila, a created moist, dark area where a mushroom that has no right to thrive can live in an LA summer.

The Death Cap looks very different at different stages. In the early stage, it can easily hide in leaf litter.

With an eye to microclimates, I set out on foot to survey that land I know I’d walked on the day Justin was poisoned. Where we have the dog fences were, as I’ve always believed, mushroom proof. Death Cap grows on oak roots and we have a lot of oaks. But most of our land is open grassland with taller oaks featuring a higher canopy. It’s hot as blazes and we don’t irrigate since we have only native plants. There are only a few areas where I’ve ever seen mushrooms. I know because I had a former Ranch Manager who was a huge mushroom enthusiast. He used to roam the property early on a foggy morning looking for mushrooms and enthusiastically bringing me to every site to show them to me. One of the few areas where he found them — other than down a steep ravine that leads to a seasonal creek — is at one end of the property that is somewhat thickly forested. This is in the area leading to Indian Leap, which is the feature our winery is named for. I don’t remember him ever showing me Death Caps, but I know we had a lot of Elfin Saddle Morrels, which are also poisonous to small animals. We had walked down there with the dogs the Saturday that Justin was poisoned. I’ve never seen a mushroom down there except in the wettest part of winter. But, with an eye to microclimates, I went back yesterday observed that the ecosystem down in that area had changed. The fires had caused a huge drop of dead leaves — sometimes two feet deep. And many trees and branches are down creating little pockets of shade under the fallen limbs. We’ve also had some construction down there, replacing a little tent cabin that burned. The workmen have been pouring concrete, a process that always seems to use a lot of water. It wouldn’t take much more than someone dropping a running hose into a thick pile of leaf litter in a shaded area to create the perfect micro-climate — even in summer — for a Death Cap to thrive. Once the spores are there, waiting to germinate, one change in conditions can cause a mushroom to sprout. It might only sprout for a day until the harsh summer conditions kill it, but it’s still deadly while it’s there.

Look at this tree, this gnarled hole, filled with leaf litter could cup moisture and create a perfect little ecosystem for a Death Cap.

Luckily, the fenced area where the dogs spend most of their time is open, grassy, has no accumulation of leaf litter and has soil so rocky that a mushroom couldn’t take hold. We have nothing but native plants down there that have open lacy leaves that let a lot of light in. We don’t irrigate these plants. But I’m going to scour every section of this area looking for micro-climates. And I now have some no-go areas for any dogs where I know we’ve seen mushrooms. Muzzles when any dog is outside the safe zone might be an option.

Death Cap isn’t the only mushroom poisonous to dogs, but it is the most deadly. Originally from Europe, it has made an amazing adaptation to American oak trees, which it needs as a host. So a quick checklist to avoid this deadly mushroom:

*Be wary in oak forests, especially in rainy seasons or in areas with cool moist summers. But Death Cap has been found in the East Coast, in Ohio, all along the West Coast. There is some indication that Death Cap is adapting to live on the roots of pines, which would allow it to thrive even in some forests in higher areas of Arizona.

*Be vigilant about the micro-climates you might create. Don’t irrigate heavily — or at all if you are in the West and can plant natives.

*If you have dense shrubbery, consider trimming up the foliage to create a clear, airy zone from the ground to a few inches up the trunk of any plant. You might still have a mushroom friendly zone under these shrubs — especially if you are irrigating — but you will be able to look under your shrubs and easily see if any are growing.

*Clean up leaf litter and consider not using thick mulch, especially in shady areas. Some people use decorative rocks or gravel for mulch. Mushrooms generally won’t grow on stones or in rocky soil.

*Be aware that the spores of the Death Cap, while not dangerous, stick to you like glitter at a Mardi Gras parade. If you walk in infected woods, then come home, you can bring the spores to your irrigated garden where the mushrooms may thrive.

*Learn to identify a Death Cap. Here’s a good guide. But be aware that there are other mushrooms that are poisonous to pets.

*This woman lost her Bernese Mountain Dog puppy to a Death Cap. She has a great blog filled with information on avoiding them.

I’m making it my mission — in Justin’s name — to save every dog I can from Death Cap poisoning. When it was first confirmed that it was Amanita poisoning, I looked at my beloved Rancho and wondered how I could continue to have dogs there. Then I remembered that, over more than ten years, we’ve had five of our own dogs and dozens and dozens of our friends dogs running all over this land — even down in the mushroom zone during mushroom season. We back up to a state park that is darker and shadier than our land and where for decades Sonomans have hiked with their dogs. Yes, this is a particularly bad year, thanks in part to two unusually wet winters and the huge amount of fallen trees, limbs and leaf litter that is creating hosting areas. But I think the situation can be managed. After all, we are crawling with rattlesnakes and no person or dog has ever been bitten here.

My sweet Justin would say, “Be careful. But don’t stop playing and enjoying life.”