Community Orchardist Winter 2021

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Allow me to link you to a beautiful piece of writing concerning chill time for fruit trees and fruit growers alike by orchardist Linda Hoffman, entitled

Fear Not. Even The Coldest, Darkest Winters Bear Fruit:

"For apples, more chill time equals a better crop. For us, living through this terrible time of social isolation, an enforced chill time, may offer us some unforeseen healing, a taste of some surprising new fruit. As slow transformations take place underground, we can also uncover new ways to relate to each other, ourselves and the earth."  Amen.

Launching Pad Dynamics

Holistic fruit growers have two primary thrusts by which to deal with disease. One is to boost tree immune function (within) as well as boost competitive colonization on the plant surface (without) with timely spray applications of nutrients, microbes, and fatty acids. The other is to lessen inoculum potential carrying over into the next growing season.

 

Much headway can be made by addressing the 'launching pad' of known pathogens. The ways we go about this vary with the disease challenge:

  • Fall hygiene practices aimed at decomposing or even removing fallen leaves on the orchard floor reduce fungal spore carryover of scab and other leaf spot diseases.
  • Pruning out fire blight strikes or branch cankers of establishing black rot on pome fruits are sensible remedial actions.
  • Blasting twig lesions and bark crevices with organic mineral fungicides while trees are dormant strikes a preemptive blow precisely where certain bacterial and fungal foes hide out for the winter months. Similarly, hydrogen peroxide can be used to clean the slate before the growing season begins.
  • Removing alternate hosts (like Eastern Red Cedar) from the immediate proximity of fruit trees makes a big difference with rusts.
  • Slathering trunks with biodynamic tree paste shifts niche prospects for canker-causing organisms. Taken a step further, applying that wet slurry of native clay/ fresh cow manure by means of a spray gun may be the best bet going against anthracnose throughout the tree canopy.
  • Picking off mummified fruitlets prior to bloom significantly lessens brown rot prospects as stone fruits start to ripen.
  • Renewing the mulch layer on blueberry bushes between growing seasons buries the sporulation cups of the mummy berry pathogen.
  • Removing spent canes when pruning raspberries and blackberries slows down viral spread from wild hosts. These need to be "destroyed" whether by burning, shredding into an active compost pile, or burying elsewhere in the orchard (under old hay, as mini-hugelkulture mounds) for lignin-rich soil investment.

 

The subtleties behind these recommendations are worth understanding, some more so than others. Somewhere, perhaps this very day… you are pondering a dormant spray of copper or lime sulfur. Let's go deeper with this particular approach to addressing launching pad dynamics.

 

Photo courtesy of Plant & Pest Advisory, Rutgers Cooperative. Extension

Use of organic mineral fungicides comes at a cost in the growing season itself in terms of arboreal biology. That's a discussion for another time. The allopathic action of these harsher materials in the dormant season, however, has a place for specific disease challenges. This isn't necessarily a do-every-year kind of decision either but one based on fungal and bacterial pressure experienced the previous season. That in turn can very much be a regional parameter as some challenges are far more persistent in warmer zones. We start with knowing which disease concerns are best addressed with dormant applications.

Bluish copper residues at half-inch green.

Peach leaf curl, for instance, might call for both a late fall and repeat winter application of fixed copper in severe cases. Autumn timing keys to leaf petioles having fallen off and thus revealing the bud scale for better penetration of material. That copper-filled microenvironment isn't conducive to leaf curl fungi waiting to come out to infect green tissue when buds pop. A similar blue whumping can be used in early spring to address bacterial spot, fire blight, and twig lesions where brown rot or pear scab fungi overwinter. The prolonged toxicity of a fixed copper application in hidden nooks (safe from ultraviolet degradation) will also serve to negate bacterial dissemination as pathogens expand to new launching sites as the weather warms. Generally, dormant copper formulations like Kocide should be applied by quarter-inch green to prevent risk of fruit russeting but growers have been known to push this till as late as tight cluster following fire blight at near-epidemic-levels the previous season. Switching to a copper soap formulation like Cueva by bloom time is a gentler continuation of this approach for addressing bacterial woes.

 

Apple scab can be compounded in warmer zones due to late-forming conidia (resulting from November/December rains) persisting in fruit buds till spring. Here's where use of lime-sulfur can prove a better choice once green tissue shows. The thinking behind delayed dormant is that fungi become more susceptible to allopathic takedown as spring unfolds… but this is indeed a double-edged sword as desirable colonization begins now as well. The Fatty Acid Knockdown (FAK) provides a holistic alternative, where high rates of fats are employed to soften lipid coatings protecting pathogen spores, followed by double-rate microbes a day later to feast hungrily on said spores.

 

A year ago in the winter edition of Community Orchardist we addressed the proliferation of leaf blotch diseases in different regions, from Marssonina and Glomarella to Alternaria and good ol' Necrotic leaf blotch. All tough nuts to crack! The following research update being shared here nearly verbatim comes from Lou Lego in upstate New York. Put on those thinking caps please, as this is truly a profound demonstration of a whole systems approach:

Marssonina Update

Lou Lego, Elderberry Pond Farm, Auburn, New York

 

I was just beginning to work on a progress report for my SARE grant on Marssonina, and thought I would send you an interesting early result from this past year’s tests.  I started work in April 2020, but as the season progressed with no rain, I requested that the further grant work be delayed until 2021, when we might have a wetter early season, and SARE agreed to the extension.   In early April I had managed to do a little work on the grant including a test in one of the orchards on the potential of a dormant spray of Oxidate 2.0 [active ingredients are hydrogen peroxide and peroxyacetic acid] at the labeled rate, on the bark and stems of a few trees including Goldrush, which had been totally defoliated in 2019.  I did this on one each of several pairs of Goldrush trees located within 20 feet of each other, stressing again that both were totally defoliated in 2019.  In this orchard I had done a thorough vacuum cleanup of the fallen leaves in fall and spring.  In September we had a brief but intense rainfall and within a week or so the tree with no spring bark spray began to defoliate and within a couple of weeks was totally defoliated.  The tree that had the bark spray had no disease and produced an amazing crop of apples . . . we are still eating them.  Now, this is of course one test, in one year, and only a brief wetness period.  But, it presents several interesting possibilities. Incidentally, we had no other serious Marssonina leaf blotch (MLB) in any other trees in the three test orchards.

1 That unlike scab, MLB may overwinter in bark and limbs of the tree.

  1. That the disease may not spread very far from one tree to another.
  2. That once infected, it may not take the long extension of wetness period as has been predicted in RIMPRO and other models.

My research advisor, Kari Peters from Penn State, plans to replicate the test there in 2021.  Their orchards were decimated this summer with MLB.  They did no leaf pick-up or bark sprays and had a bit more rain than we did.  Kari has done much of the research on this disease in this country, formerly at Cornell Hudson Valley and more recently at Penn State.

Goldrush without spring bark treatment.

Photo by Lou Lego

So, I am writing to let know about the work, and hoping that you might try the technique on a few trees in your orchards. I would love to have this work out for organic apple growers, particularly since many conventional experts have said, almost with glee, that MLB may mean the end of organic apples in the Northeast.
Apple Tree Decline

Fruit trees can pass on before their time for any number of reasons. David Rosenberger of Cornell gave a talk several years back on the leading causes of apple tree decline. His write-up will help you further distinguish particulars:

http://www.hort.cornell.edu/expo/proceedings/2017/TreeFruitPestMGMT.AppleTrunkDisorders.Rosenberger.2017.pdf

Fire blight in the rootstock

Dwarfing stock like M.26 or M.9 are the most likely to be subject to bacterial demise. Rootstock infections usually develop near the graft union as a result of internal movement of the pathogen through the tree or from infections of root suckers. The bark of infected rootstocks may show water-soaking, a purplish to black discoloration, cracking, and signs of bacterial ooze. Red-brown to black streaking may be apparent in wood just under the bark. Symptoms of rootstock blight can be confused with Phytophthora collar rot. You get a big leg up propagating trees on seedling, MM.111, M.7, Bud.9, or any of the Geneva series of rootstocks.

 

Herbicide injury

Photo courtesy of the American Phytopathological Society (APS)

One thing that organic/ biodynamic/ holistic fruit growers need not worry about!

 

Boring insects

Borers unchecked undo the cambium connection to the root system.

Black stem borers and dogwood borers rate notice in the Rosenberger rundown. But what about the infamous round-headed apple tree borer (RHAB)? The curse of the borer can best be prevented with trunk treatments of neem oil, as detailed in this recent post on borer repellents in our grower's forum.

Winter injury

Sunscald can occur when the winter sun heats dark-colored trunks on the southwest sides of trees during the afternoon and then those tissues cool rapidly come nightfall. This gets accentuated by reflection from snow cover, especially in lower branch crotches. So-called southwest injury can be minimized by coating younger trunks (with smooth bark) with diluted white latex paint or kaolin to reflect the solar gain by day. Biodynamic tree paste will help damaged cambium tissues regain continuity.

 

Trees generally will callus over both frost and water-related stress cracks.

Photo by George Weigel.

Early winter injury of the lower trunk can occur when growth continues late into the season. A warm fall ending with an extreme temperature drop in late November or December can prove more damaging than deep cold later on. Trees do best when gradually acclimating to cold temperatures. Nursery stock that has been pushed with too much fertilizer is especially susceptible that first year after planting out.

 

Frost cracks result from cambium tissues freezing overnight and then splitting the bark apart vertically when the rising sun quickly thaws it. This expansion-related cracking happens particularly to thin-barked varieties on the eastern exposure.

 

Drought stress

Lack of moisture during extended heat periods may predispose the trunks to invasion by Botryosphaeria dothidea, a canker pathogen that is incapable of killing the cambium in healthy functioning trees, but which becomes very pathogenic in drought-stressed trees.

 

Wood-rot pathogens

Winter-damaged tissue subsequently colonized by black rot. Two strikes and you're out!

Welcome to double whammy territory! Tree decline caused by rot organisms are more common in older orchards and only once particular trees have been compromised by other injuries or environmental factors.

Latent apple viruses

Incompatibility at the graft union makes for done deal sooner rather than later.

 

Apple union necrosis. Photo courtesy of Michigan State University

Tomato ringspot virus is often the causative factor behind longer term graft failures. A resistant scion grafted onto a tolerant but susceptible rootstock, most commonly MM.106 and P.2, presents symptoms approximately 4–6 years after planting. Yes, usually once the tree is capable of finally bearing a full fruit load!  Affected trees show a general decline beginning with delayed budbreak. The canopy tends to be sparse, bearing small, pale green leaves, and premature defoliation is possible. A distinct black, sunken line at the union is apparent underneath the bark. The graft union may be weakened to the point where the scion and rootstock separate partially or completely break away under stressful conditions.

 

Using virus-contaminated budwood to propagate new trees will show up much sooner. This results in a low success rate in the nursery, with reductions in bud survival ranging from 20% to as much as 67%. Grafting on G.935 rootstock seems especially problematic. Virus testing is the only means by which a nursery can be sure of the quality of a scion source.

 

Wet Feet

A high water table may be a factor if declining trees occur in areas that are known to have poor drainage, but most orchards today are planted on good sites where one would not expect saturated soils to persist long.

 

Those Damned Voles!

He doesn't mean me, does he?

Meadow voles can girdle young trees at the soil line, and even higher under snow cover. Pine voles literally make the root system of young trees look like a carrot. The damage is easy to identify in either case and will instill in you a lifelong passion to stay on top of any and all rodent situations.
Q&A with the Orchard Consultant

Is fermentation essential to make the silica & calcium tea sprays? It really gets quite the stench... We've been making buckets of nettle and comfrey teas and just letting them sit for a couple or three days before straining and then adding them to the spray tank. Do you think that is effective at all? And is adding horsetail and garlic really essential?

 

Fermented plant extracts (FPE) are basically a nutrient tea with biological impetus. Herbalists will use the word infusion to put the emphasis on longer brewing time for a medicinal tea. This allows the bulk of the phytonutrients in the plant material to be extracted. Thus your "quick tea" will provide some of the nutrients but not necessarily all. Using hot water to facilitate extraction would help with this. Biology does this equally well: The facultative organisms found in effective microbes (EM) enhance the breakdown process of the plant material. You can tell populations have reached peak form after several days when the brew pushes solids upward. Microbial populations on the surface of plant material can serve as well provided recent rain has not washed off the majority of yeasts and lactic acid bacteria. This life force aspect of an FPE will carry through only if organisms are given time enough to increase their numbers while assimilating nutrients. Still, don't think of these enhanced plant teas as being in the same category as a compost extract or a compost tea. That the spent plant material will no longer hold any color after a proper brew time serves as a pat on the back.

 

Nettle is great as a perk-me-up application, whether applied in the garden or the orchard. Comfrey adds significantly to the calcium crescendo. Horsetail along with seeded nettle provides silica in a plant-available form. Solid chunks of garlic, whether leftover cloves from the previous year's harvest or freshly cut scapes, will only get fully incorporated into a brew that sits 7 to 10 days. Many different plants have value. Don't overlook the humic acid step to further help chelate (stabilize) nutrients in a FPE after forking out the plant material onto a compost pile. This will help abate the "essence factor" a tad as well.

 

Biodynamic tradition (whoever may have said this) states that it's through fermentation that nutrients become more bioavailable. Truthfully, a "fermented plant extract" has limited sugars by which to feed the yeasts to produce much in the way of alcohol. An herbalist would reasonably argue that alcohol-soluble constituents would be left behind as a result, especially if using resin-rich herbs. . . which we're not for growing purposes. Korean Natural Farming extolls the virtues of fermented plant juice (FPJ) which includes the addition of a carbon-rich sugar to the brew. You add essentially the same weight of brown sugar as plant material, tossing all together in a large bowl, coating the leaves and stems thoroughly. This expedites the osmotic process thereby drawing out the "plant juices" in as little as 3 days. I have not worked with this but suspect the sugar may also alter the aforementioned stench factor favorably.

 

Still, when all is said and done, there's nothing like liquid fish and plant brews to maintain social distancing during a viral pandemic!

 

 

There is a common understanding that healthy soils create healthy plants. The reverse is also true. Healthy plants with high levels of energy can send as much as 70 percent of their total photosynthates into the soil through the roots at some stages of growth. These root exudates are the fuel that drives the soil microbial community and leads to the rapid formation of organic matter. This process, called carbon induction, is the fastest and most efficient way to sequester carbon and build soil organic matter.

—John Kempf, AEA

 

 

 

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Network Support

Hearty thanks to the growers and sponsors listed here. These are the folks who have contributed financial support for these efforts since the last newsletter.

 

Generally speaking, it takes twenty or so names on this list to finance a next newsletter. That goal was met for the first three issues of 2020 but we indeed came up short last fall. The growing season demands attention; I get that. Equally apropos, it helps to have contact from headquarters to serve as a reminder that this work has value.

 

If this content matters to you, please consider doing your bit right now. Sharing these holistic insights "freely" actually requires real time support.

 

Stay in touch, think deeply, and treasure those venerable trees!

Michael  Phillips

 



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