Tag Archives: pathogens

Pathogen-Reducing Compost

January 14, 2020
© 2020

Benefits of compost are widely known: 1) enhances water holding capacity, soil structure, organic matter, drainage, and nutrient holding capacity of soil, 2) provides a source of beneficial microbes, 3) decreases both inputs (to your garden) and outputs (from your garden), a plus for sustainability, and, 4) reduces fertilizer and pesticide use.

However, did you know that well-made compost has the ability to reduce pathogens and enhance plant growth?

An extensive research study of 120 bioassays, involving 18 composts and seven pathogens, found positive disease suppression in 54 percent of the treatment combinations, a disease stimulating effect only rarely (3%), and no effect in 43 percent of the treatment combinations (Termorshuizen et al., 2006).

Other studies have shown that “backyard” compost is superior to the commercial product, possibly due largely to richer and varied starting materials, plus a more relaxed thermophillic phase (wherein temperatures are sanitizing but lower than those recorded in commercial composts). Backyard composting presented higher counts of bacteria, actinomycetes, and fungi. It also shows higher percentages of isolates producing extracellular enzymes which allow the breakdown of tough substrates, including polyethylene!

Although the studies show the efficacy of compost, no one has come up with the perfect recipe or management strategy to combat a particular soil pathogen. This is because the soil microbial community is so dynamic and complex. Quality control tools are also lacking.

Still, we know from research that microbial organisms in compost are able to reduce pathogens my means of: direct antagonism (antibiotic production and direct parasitism), predation, competition for resources, enzyme production, and, induced resistance in plants – through signaling networks and hormones.

Sun, Jan 19, 2-4. work party
Sat, Feb 1, 10-12, Work Party
Sat, Feb 1, 1-3, PRUNING CLASS
Sun, Feb 16, 2-4, Work Party
Sat, Mar 7, 10-12, work party

Note, compost is more effective as a pathogen prevention method than when used as a management strategy for some existing soil or plant pathogen. Elaine Ingham, veteran soil scientist, points out that compost and soil should be colonized with a sizeable and diverse body of microbes. “There are only so many seats at the table. If the good guys are already there, the bad guys are turned away.”

Image Credit: Zosia Rostomian & Jill Banfield, Creative Services, Berkeley Lab

Who are these microbial actors who play such a beneficial role in a garden? It’s bacteria, fungi, protozoa, and nematodes, none of which can be seen with the naked eye. There are millions of microbes in a gram of compost and hundreds of thousands different species. In fact, it’s the diversity of players that makes good compost a pathogen suppressor.

Commercial composts can differ widely in their suppressive effects and can vary as to which pathogens are diminished. However, commercial composts can meet the objective of adding organic matter to the soil. In contrast, the special compost that you can produce with backyard composting, using correct temperature, moisture, aeration and curing processes, will yield a compost that you can use sparingly as an inoculum throughout your garden. It will jump-start good soil biology and maintain nutrient cycling, creating an environment fostering pathogen-suppressive soil.

Next up – A template on making a thermal compost.
Also, watch the FreewayEstates.org calendar for a hands-on thermal composting class, coming in early May, 2020

Ruth

References:

Hadar & Papadopoulou, 2012 – Suppressive Composts: Microbial Ecology Links Between Abiotic Environments and Healthy Plants DOI: 10.1146/annurev-phyto-081211-172914

Vaz Moreira et al., 2008 – Diversity of Bacterial Isolates from Commercial and Homemade Composts. DOI: 10.1007/s00248-007-9314-2

Welgarz et al., 2018 – Microbial diversity and nitrogen-metabolizing gene abundance in backyard food waste composting systems DOI: 10.1111/jam.13945

Fayolle , L., 2006 –  Eradication of Plasmodiophora brassicae during composting of wastes
https://bsppjournals.onlinelibrary.wiley.com/doi/full/10.1111/

Cangelos, G, 2014, Dead or Alive: Molecular Assessment of Microbial Viability
https://aem.asm.org/content/80/19/5884 DOI: 10.1128/AEM.01763-14

Welcome to our Demonstration Garden!

May 14, 2019                                                                                                      DONATIONS PAGE LINK

The fruit trees in the orchard this year would amaze anyone. They are striking and flush …
with pests. It’s true. Come and allow us to demonstrate all manner of pest infestation plus other unsightly disorders.

Last year was a record bounty but, this year, we are counting on one hand the number of fruits from most of the trees.

Why, on one small branch of the Mirabelle plum (photo) you can view tip dieback from brown rot, scale, aphids and leaf roller damage. The pear, just after the height of the leaf roller infestation, has now been chewed to smithereens by the California pear sawfly (photo).

Wander over to the Fuji and notice apple blister mite. Then, check out the powdery mildew on the William’s Pride.

This situation takes me back to coaching where you had to make sure you didn’t spend all of your energy on the one high-maintenance kid and take for granted the other 14 well-behaved teammates. So, yesterday, I coddled our precious persimmon. The persimmon, like the mulberry, sits and watches the devastation and only asks for a drink of water now and then. I composted-in-place its weeds, fed it some nice compost and leaf litter, and laid out a coat of chips on top. Namaste.

Sun, May 19, 2-4, Work Party
Sat, Jun 1, 10-12, Work Party
Sun, Jun 16, 2-4, Work Party
Sat, Jul 6, 10-12, Work Party

Back in February, Allison and I thought we had the winter moth larvae in check. We had banded the trunks then flattened the eggs below the band. The problem was, while we were focused down on that trunk, the winter moth larvae soon would be sailing through the air, landing on whichever fruit or nut tree was within striking distance. Much like a skilled parachutist, I think they tug a certain way on that silken thread to ensure they make it to the canopy. In April, they were landing on our sweaters and hats faster than we could squish them off the leaves and blossoms. We had kept our own trees from propagating larvae but we were defenseless against tall neighboring trees that spit out the little buggers like factories.

Yesterday, I sighed as I cleaned off more dead material from Liberty branches (photo). Oh, but then I looked closely. Was that a little speck of green? Sure enough, the tree is pushing out a new leaf where the others had been eaten.(photo) The Liberty is willing and ready to try again. OK then! We will also find energy to grow and prepare for the next obstacle.

Ruth