With the exception of a couple of Antonovka, I can’t keep apple trees alive on my place. Pear trees don’t do a lot better. There are some black walnut trees on my place and some people say there’s a compatibility issue. A couple of years ago, in an attempt to save a dying pear tree, i planted a callery pear next to it. Within inches. Then i grafted them together. The graft failed but both trees survived. The Ayers pear never looked better, and the callery just sits there, not growing. Strange. I think i might transplant callery pears next to some of my sick apple trees. Can’t hurt.
I just finished reading Finding The Mother Tree. Great book which talks a lot about mycorrhizal fungi and how trees help other trees . Might explain what I’m seeing with this Ayers pear.
Interesting observation! I’m using the idea of microbe-plant compatibility to guide the placement of everything on my property. I studied microbiology in grad school, and the concept seems to jive with everything I learned about microbial community behavior, so I think it’s worth a try.
I’ll hae to check out that book you mentioned!
That is why I religiously ad weathered wood chips and old leaf/needle litter to my trees when planted. You can see they have the hairy fungi already at work.
Thanks to TennHunter for that great tip on an endless mulch source!
Is there a resource for this information?
Yes! The theory is based on some of my companion planting observations and a couple of well-established concepts that soil scientist Elaine Ingham discusses in almost every podcast interview she gives. The ones I listened to specifically were Nature’s Archive #39, Sustainable World Radio #128, and The Joe Gardener Show #117.
I’ll discuss each concept individually before describing how they can be put together and taken a step further:
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Bacterial vs fungal dominated soil: The microbial communities in soil where annual plants and perennial plants thrive are dominated by either bacteria or fungi, respectively. Conversely, soils in which those plants don’t do well often have that microbial dominance reversed (i.e. perennials don’t thrive in bacteria-dominated soil and annuals don’t thrive in soil where fungi make up the majority of soil microbes). In her interviews, Elaine Ingham suggests using woody perennials (thyme, lavender, rosemary, etc.) as groundcover to help promote soil fungi populations. She also discusses different mulch types for different crops because bacteria and fungi have different food preferences: fungi prefer wood-based mulch and bacteria prefer non-woody much such as grass, leaves, hay, straw, etc.
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Ecological succession: This seems to be a well-established concept already, but I first heard about it from one of Elaine’s interviews. I’ve also seen this first hand. Ecological succession is the tendency of a disturbed area to be colonized by different types of plants in a predictable sequence. After a large swathe of soil in a temperate environment is disturbed and the plants growing in it removed, it is first recolonized by lichens and annual weeds. This may be because the bacteria in the soil are more resilient against disturbance than the fungi (reference here). If most of the fungal mycelia in soil are killed off, bacteria remain and proliferate, thus making that soil more hospitable to annual plants than to perennial plants. After the lichens and annuals are in place, grasses and perennials begin to appear. The presence of grasses and perennials coincides with an increase in soil fungi populations (reference). Do increasing fungal populations cause the increase in perennial population, or is it the other way around? Elaine Ingham believes that the interaction is more of a mutualistic feedback loop: fungi in the soil help perennials to grow, and more perennials in the soil help fungal populations to increase. Eventually, the grasses and perennials replace the lichens and annuals. This process repeats itself until a forest has taken over the area.
I skipped over a bunch of details in the synopsis above because I don’t want to make this post longer than necessary. Suffice it to say, if you have questions about the role of soil microbes in ecological succession, check out the embedded links above.
- Companion Planting: I’m not referring here to companion groups for which the supportive function of each member is obvious (i.e. marigolds and fig trees, where the marigolds help the fig trees grow by deterring nematodes). Consider instead peppers and cucumbers. When I started gardening, I planted peppers, cucumbers, and tomatoes in pot-sized raised beds. Each plant had its own bed except a cucumber and a pepper that shared a bed. The cucumber in this bed grew up a trellis on the North side of the bed, so it wasn’t shading the soil or really providing any obvious service to the pepper. Initially I assumed that both plants wouldn’t grow as well as their counterparts that had beds all to themselves because they’d compete for resources in the bed they shared. To my surprise, the pepper plant in the shared bed grew 50% larger than the 2 other pepper plants of the same type in individual beds. I guess this isn’t so much a separate concept as it is supportive evidence that there was probably an interaction going on in the soil between the cucumber plant and the pepper plant. I suspect that together they could promote soil fungal growth better than each plant would in isolation.
I want to apply these 3 concepts to my planting scheme in the hope that doing so will reduce the amount of time, money, and labor I have to put in to food production on my property. Here’s how I’m doing it:
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I only plant perennials, so I want to promote fungal dominance in my soil. I’m doing this by using cardboard and wood chips as mulch. Once that’s down and has rotted for a season, I plant perennial groundcovers (not necessarily woody ones).
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Perennials are best planted with other perennials, in general. I’m sure there are exceptions. Here’s where my contribution to these concepts comes in: Why not go a step further and group plants according to the type of environment they naturally inhabit? For example, East TN forests have a fairly consistent botanical community makeup: tulip poplars, oaks, hickories, black walnuts, pawpaws, spicebush, dogwoods, solomon’s seal, poison ivy, and virginia creeper, to name a few. I think it’s reasonable to suppose that these plants are good companions because otherwise they wouldn’t appear all together so consistently throughout East TN. I strongly suspect that the reason why they’re good companions has something to do with the mutually beneficial soil microbes these plants foster.
In my case, I’m choosing iceplants and sedums to grow beneath my jujube trees because I’m assuming that the dry areas where those ground covers are native are at least somewhat analogous to the Asian steppe where jujus grow naturally. Likewise, I’ve got strawberries under my mulberry trees because both are forest-dwellers.
Hey Dean, are you familiar with Juglone toxicity?
If that is the challenge you are experiencing, I’d recommend a shift in species for more success. Pawpaws, persimmons, and mulberries might be a better pick than pears and apples.