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scab observations 2015

Posted by Michael Phillips 
scab observations 2015
June 03, 2015 01:51PM
Curious what others are seeing in their orchards as regards apple scab? Let's talk. This spring has been sort of dry in the Northeast, with only a few limited rains at night, followed by the canopy drying out quickly in the morning, thus limiting infection probability. A grower's dream! I am currently finding no scab anywhere on any dessert or cider variety; the leaves on my trees are absolutely beautiful.

All this rain the past three days (May 31, June 1, June 2) may change that picture. I've made several holistic sprays so far this season, with 'Spring 3' (petal fall timing) made May 29. A good 40% chunk of ascospore discharge at this site for the season will have been released by these rains. Earliest signs of resulting scab will only show up another 7 to 9 days from now, and I will report back in.

NEWA reports that ascospore discharge is essentially now done across New England ... we are at 848 degree days here in Lost Nation ... and so can confirm what "the curves" have to say as well. [See pages 184-5 of Apple Grower to get familiar with the scab dance, if you're not already.]

I did find two scab lesions on five acres of trees in southern Maine yesterday, which would correlate to the wetting period during bloom, back on May 22. But those were only found a few hours into a commercial consultation while walking the entire orchard with the grower. One leaf apiece on two different trees ... far from an epidemic by all accounts! The day before, in an uber-mineralized orchard in Harvard, Massachusetts, not a sign.

Lost Nation Orchard
Zone 4b in New Hampshire



Edited 1 time(s). Last edit at 06/03/2015 08:30PM by Michael Phillips.
Re: scab observations 2015
June 05, 2015 08:16PM
Way out here, three hours west of Seattle, we actually have had a somewhat similar spring. Very, very dry until it rained a couple days in a row on the cusp of June. Also, quite cool until recent weeks. In fact almost the same temperatures as we had over "winter".. People began mowing lawns in January this year when they typically would start in February. For a recent Minnesota transplant this takes some getting used to. The bees were slow going (thank Dios for bumblebees!!).

As you know, Michael, we have fairly serious scab problems in an inherited, maintenance-deferred orchard planted in about the same year I was.. 1984-ish. We are newbie-orchardists, but it was clear that the scab is bad enough to be affecting photosynthesis and tree health. We mulched over last year's fallen leaves with our own hay. We got the first spring holistic spray in (with homemade aerobic activated compost tea in place of EM) and neem (not sure any made it out of the tank as our hard as nails water makes emulsification a real chore!). That was a several weeks ago now, just after finishing pruning and right as the very first king blossom opened.

Now with our 200+ varieties it's almost impossible to time sprays to avoid spraying open King blossoms.. So while waiting to spray, our strategy was to let the grass grow tall, and it was 6' (the height of our trees!) some of it, when I went out last week with my most prized possession - the Austrian Scythe. So damn much fun. Scythed the entire acre by myself, leaving broadleaved plants alone.

I don't have a Degree Day count, but most likely we were at 1000+ hours as our first rain in over a month fell on the cusp of June. Not seeing any scab yet (will have to wait those 7 days though) but identifing new issues (possible anthracnose and other cankers) at this point.

Tomorrow we will do our 4th (2nd, really) spring spray with our brand new Pak tank (yes that golf cart rig was cool but 8+ hours spraying was too much for us). We tried a pretreatment technique with the AACT to increase fungal counts which I'll hope to verify via the soil microscope.

Now with so many new variables in our old orchard it will be hard to say which one licked the scab fungus but I hope to be making the claim that holistic practices did real soon.

Wildcat Valley Farm
Zone 8b
Olympic Peninsula Rainshadow
Port Angeles, Washington
Re: scab observations 2015
June 08, 2015 07:19AM
We're in the other hemisphere, but we too had an exceptionally dry spring (Sept/Oct/Nov 2014), and our crop in 2015 which we have just finished harvesting, was the cleanest we have had in the 13 years we have been growing apples organically. We applied fewer wettable sulphur sprays than usual, and no lime sulphur sprays were needed. Apple scab on fruit amounted to a fraction of one percent.

(While the theory says there should be a reduced spore load this coming spring, we're totally certain there will be more than enough spores out there to totally wipe us out if we get too relaxed).

Kalangadoo Orchard
On the “other side” in South Australia
Re: scab observations 2015
June 13, 2015 04:58PM
Craaazyist year ever! That is true almost every year. My scab magnets are the cleanist ever--Braeburn and Fuji have been so bad the last 4 years I juiced them all---not worth sorting, BUT 2015 they are so clean it is scary. There is the usual amount everywhere else but nothing crop threating. Michael as usual beat me to the punch on a scab report. I have to say here in California, at least in my part, after keeping Degree Days for nearly 15 years and playing with testing the McCready charts and No Release during darkness--I should have NO scab this drought year. But, I got some anyway. BUT, once again as I have reported in the past 2 years, very little has gotten onto the fruit! WHY? Has the Neem and Fish built up enough immunity by the 4th Spring Spray to fight off secondary infection but not enough to STOP first infection. Oh, I'm not saying none got on the fruit, but I would say 70-80% less than the leaves suggest. I did use sulfur twice in 1/4 of my acreage and they are nearly super clean--hard to find any scab except in the Pink Pearls. I'd really like a "normal" year (hah) to see if sulfur will be with me the rest of my life---only time will tell.
Good luck to Nick above--I am humbled by my mere 80 varieties and sympathize with trying to put on sprays with proper timing to avoid blooms and all that. I have to waste alot of time (and fuel) to follow 1/4 inch to bloom to try and get it right. After bloom it gets a little easier. We should compare some West Coast notes.

The Apple Farm
Zone 8b in California
Re: scab observations 2015
June 16, 2015 11:02PM
Hello All,
I will add my apple scab report. I have not noticed anything in my trees ( Haralson's, Cortland, Winesap, Honey Crisp, Duchess). Leaves are all in pretty good shape. I did see some gold ringed spots on the Cortland, I believe it is apple cedar rust. It is not wide spread through out the tree.

Last year was a very wet spring and early summer. I sprayed with conventional chemical sprays last year (I am a new convert to the holistic approach). What I noticed was my flowering crab apple tree (which was never sprayed) and many others in the vicinity looked awful and by August they had few leaves left and leaves I saw were blotchy like the pictures I saw on the internet for apple scab. I assume that is what it was. Does this sound right as being apple scab?

Thanks,
Russ Martin
Extreme West Central Wisconsin Zone 4b Hager City



Edited 1 time(s). Last edit at 06/19/2015 08:07PM by Russ Martin.
Re: scab observations 2015
June 18, 2015 11:38AM
This week revealed a few visual signs of scab, being that vague fuzziness in leaf veins on young growth. Very hit or miss yet always the 3rd to 5th leaf back on actively elongating shoots. The June 1 -2 wetting event (which launched this post) is the likely timing for when these infections took hold. Honeygold, Bethel, Sweet Sixteen, Zestar, and Pink Pearl had a leaf or three showing scab fuzz. Nothing to report on varieties like MacIntosh, Gravenstein, and Gala. Fruit here now approaching 20 to 25 mm size, so this may well turn out to be a beauty year on the disease front.

Tim makes a good point about halting secondary infection with nutritional/ fatty acid sprays. Part of this is immune function at full bore; part of this is calcium and silica boosts to the cuticle of leaf and fruit alike. I also find leaf scab not going to the fruit. Cool. A little disease presence contributes to Systemic Acquired Resistance (SAR) resulting in a further phytochemical boost. All to the good for producing antioxidant-rich fruit.

Lost Nation Orchard
Zone 4b in New Hampshire



Edited 1 time(s). Last edit at 06/18/2015 08:09PM by Michael Phillips.
Re: scab observations 2015
June 22, 2015 08:10PM
The past couple weeks we're seeing scab rearing it's ugly head in the European Pears. Seeing little in the apples still (compared to last year). This is encouraging. We are continuing AACT sprays weekly (with comfrey/nettle and horsetail when we can find it) throughout the summer. Our attention has been turned to likely fireblight.

Tim- I am humbled myself at the 70 year old man (now 92) who planted our orchard and collected all those varieties in his travels (20+ years ago). Yes, let's talk West Coast - I'll DM you.

Wildcat Valley Farm
Zone 8b
Olympic Peninsula Rainshadow
Port Angeles, Washington
Re: scab observations 2015
June 29, 2015 07:36PM
For 2015, Scab has been minimal in my orchard both at my place as well as those I am overseeing locally. I put a good amount of credit in the Fall Orchard tidying up as helping substantially to set the stage, year over year, with 'best foot forward' preparations for each new springs holistic spraying to begin.

This year was a soil analysis year and after seeing a still stubborn acidic pH along with a deficit of Calcium again, I planned to deal with these issues for this coming growing season, so in mid Jan I ordered up enough calcitic lime and gypsum to apply a 600#/ac amount. As we had barely had any rain by that point, I do believe that the additional lime may have had an additional stifling effect on the maturing scab fungi too.

I have seen less scab this year than I anticipated, as we too (Sierra Foothills at 2,700ft elevation) had a very dry winter (40% less than normal), that was punctuated by a small handful of extended wet periods, in between. I estimated the spore releases should have been mighty ones, due to the priming of the scab fungal pump for release, when those wetting periods finally came to our parched land; but if those releases did indeed hit, my trees repelled the assaults - proof being in the lack of scab infection seen overall. I definitely put faith in my general orchard care and to my holistic spraying to carry me through . . . all was going really well and then the FB strikes hit and I shifted all of my energy to the care of the trees themselves. Fruit became a secondary concern, especially with several FB susceptible varieties.

Some select highlights of the orchard calender notes from this year, so far . . .
Jan 28-29 - spread and incorporated sizeable amount of limestone
Feb 26th - 1st Holistic (1/4in, averaged)
March 6th - 2nd Holistic (pink, averaged)
March 20 - 1st coddling moths trap captured (later than I expected based on the warmer weather and earlier blooming)
March 22-31 - Peak Bloom, over majority of my apple varieties.
March 27th - Solo Bt Spraying at 2lb/a (Dipel) to deal with two varieties of caterpillars attacking leaves
April 3rd - 3rd Holistic (petal fall, averaged, skipped anything still in bloom)
April 4th - Sprayed THAT flowable Sulfur (rate = 2 quarts/50 gal) on a handful of trees showing Powdery Mildew (acknowledged the likely help with scab protection of those varieties sprayed as well, and a detriment to the 3rd holistic I just put out days earlier)
April 7th - 1st and only snow of the year . . . 1/2in of snow and temps at barely 32 after an overnight of 1.25in of rain.
April 10-11 - Fireblight noted on a dozen varieties of Apples and Pears
April 12th - 4th Holistic was penciled in for here and skipped while I shifted my total attention to FB
April and May - FB strikes eventually show up, at some level or another, across 80% of my trees. Various dates in the attack and counter attack of Me and my trees vs FB in the orchard.

Scab has made a minor mark here and there at my place this year. more on leaves than fruit, and I too subscribe to the immune system boost that comes with a 'little bit' of infection being out there amongst the trees . . . So a little scab doesn't scare me too much anymore . . . Overall, it is a pretty clean scab year here.

Paul

Gopher Hill Apples
Zone 8 in California
Re: scab observations 2015
July 07, 2015 04:44PM
Paul-

Excellent information! I had actually been thinking that what you just did would be a great idea. That is- I'd love to compare "orchard year" calendars with other growers to compare and contrast. Maybe we could start a new thread on this. I don't actually have much to contribute yet (we finally starting keeping records these past weeks after deciding to get organized). But by next year I can contribute an entire year's worth of information. What does everyone think? Forum administrator - lets create a thread like this, it would be so rich with information!

Nick Segner

Wildcat Valley Farm
Zone 8b
Olympic Peninsula Rainshadow
Port Angeles, Washington
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