Mycorrhizal fungi helps plants survive high temps in containers
I've been reading about Mycorrhizal fungi for some time and found that with container grown plants, much of the anecdotal evidence is contradictory. I've found 2 really good research articles from Texas A&M about using Mycorrhizal fungi in the nursery container business. These were plants grown in black nursery containers in Texas summer heat during July and August. The research compares the effectiveness of fungi inoculants with both organic and inorganic slow release fertilizers. For others that might be interested, I've summarized some of the important information from both studies. At the bottom are two links to download the PDF files of the published studies.
These studies contradict at least three common myths I've seen about why Mycorrhizal fungi are not needed with containers.
Myth 1: The inoculants are worthless because the fungi are naturally occurring, so plants grown in the ground don't need them, and when growing in containers, the high soil temps will kill the fungi. The truth is that even with root ball temps over 110 degrees, the fungi flourish as long as the plants survived to support them. The high temps of soil in containers does suppress the growth of bacteria needed for nitrification of organic time released fertilizers, so Osmocote was more effective than time released organics for plants in containers during hot weather.
Myth 2: The fungi help with a plant's uptake of phosphates in nutrient poor soil, but if you fertilize your plants, the phosphates will kill the Mycorrhizal fungi. The truth is that the beneficial effects of the fungi were significantly greater with high soil fertility.
Myth 3: Many organic gardeners say that good quality compost is so teaming with beneficial microbes, it will have all the Mycorrhizal fungi that plants need. Others say that the temperatures in a compost heap will kill the Mycorrhizal fungi. The truth is that these fungi are symbiotic with the roots of living plants and cannot grow except with the roots of living host plants. Good quality compost can provide many other beneficial microbes for plants, but Mycorrhizal fungi can't grow in a compost heap.
The articles show that organic slow release fertilizers did not work as well in containers during high temps, most likely because the heat kills the beneficial bacteria needed to break down organic sources of nutrients. The high temps also make the time released inorganics only last half as long as at lower temps, but plants did not suffer any negative effects from the Osmocote, even though nutrients were released almost 70% faster than normal due to high soil temps.
These studies found that the Arbusular Mycorrhizal fungi did survive the high soil temps in black nursery containers. They found that the transplants that were inoculated with the fungi grew much better than those without the inoculants. Both the organic and inorganic fertilized plants did better with the fungi inoculants. Inorganic time release fertilizer with the Mycorrhizal fungi were the best combination for container plants.
Two different inoculants were tested in one of the studies. One inoculant was a single strain of fungi and the other brand contained multiple strains of fungi. The multiple strains worked better, but even the inoculant with a single strain of fungi was a significant benefit to the plants during high summer temps.
Unfortunately the brand of Mycorrhizal fungi inoculants used in these studies are not available to the retail public. Does anyone have any experience with a good inoculant that is available in small quantities for a home gardener?
I've got about 20 containers with dwarf fruit trees, blackberries, and grapes. I want to see if adding Mycorrhizal fungi will help them cope with high soil temps during summer in containers. I planted my trees this spring in 18 gal containers and pruned their tops so their roots are adequate this year. The root systems will have to work much harder as the plants grow bigger and begin to bear fruit during future summers. I am want to see if I can get them prepared to survive future hot summers in a "sweatbox".
There are several Amazon sellers that have Mycorrhizal fungi inoculants for sale. They charge about $15 for enough for 50 container plants. I've seen the "Great White" product from Plant Success recommended highly on other websites, but it does not come in any small sizes. The other products from Plant Success are less expensive, but contain fewer beneficial organisms.
Mycorrhizal Fungi Plant Tabs for Veg & Flowers from JRM Chemicals (12 strains - 7 Endo & 5 Ecto)
Rooter's Mycorrhizae from Hydro Organics Wholesale (8 strains - ? Endo & ? Ecto)
Ecto Tabs Mycorrhizal Fungi Tables from Ecto Tabs ( 5 Ecto strains for nut trees)
Mycor Root Builder from GreenSense (? strains)
Garden-Ville Mycorrhizal Fungi from Garden-Ville (3 strains - 3 Endo)
Nature's Solution Mycorrhizae from Nature's Solution (5 strains - 4 Endo & 1 Ecto)
Plant Success Mycorhizae Granular from Plant Success (11 strains - 4 Endo & 7 Ecto)
Plant Success Mycorhizae Tables from Plant Success (17 strains - 8 Endo & 9 Ecto )
Plant Success Mycorhizae Soluable from Plant Success (18 strains - 7 Endo & 11 Ecto)
Great White from Plant Success (18 strains - 7 Endo & 11 Ecto)
I've read some discussion on other websites and found that many growers of "medicinal herbs" swear by the "Great White" products from Plant Success. While the herbs I grow are basil and rosemary, I must admit that the pictures they have of their "medicinal herb" plants are really something. They have really remarkable and beautiful foliage for plants grown indoors in containers. Before having all the information we have now on the web, I used to buy a copy of "High Times" once a year, because it had the latest information available on hydroponics, container growing, gardening in small spaces, and indoor gardening. Those growers are still a great source of information for gardening ideas that you won't get from from Martha Stewart or see on the HGTV network.
A word of warning if you are growing azaleas, blueberries, permissions, heathers, or rhododendrons. These plants in the Ericaceae family need Ericoid Mycorrhizal Fungi, that are different from those needed by most other plants. I have not found a source of small quantities of Ericoid fungi inoculants. You only need a small amount, about like you would use of rooting hormone for a cutting. An entire pound of the stuff for $50, and way too much for my 3 blueberries bushes. There is a large group of wild persimmons growing in a vacant lot near my house, so I'm going to take some small soil samples from around these persimmons and add it to my blueberry containers. I'm also going to keep an eye open for wild growing rhododendrons as well to collect some small soil samples to use to inoculate my blueberries. I'm hoping this might help give my blueberries some help coping with next summer's heat, when I hope to have my first crop of berries.
If anyone can recommend a brand of Mycorrhizal fungi which has helped their plants, I would greatly appreciate it.
PDF files of the two research articles can be downloaded at the links below:
Here is a link that might be useful: Mycorrhizal fungi with organic and inorganic fertilizers for growing container nursery plants