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Marssonina 2021

Posted by Michael Phillips 
Marssonina 2021
July 15, 2021 04:24AM
The conversation concerning leaf blotch is about to make a major comeback. I'm starting a new thread to direct immediate attention but please know this builds on an earlier thread entitled Marssonina 2019

I was in southeastern Vermont yesterday for a consultation, and then dropped by Scott Bolotin's orchard on the way home. His trees are almost all yellowing, starting to drop leaves en masse, and no question it's Marssonina Leaf Blotch. The similarity to Frog-Eye Leaf Spot on those leaves still with green hue gave me pause but there's no escaping that yellow finale. What's significant in this case is that the hundred varieties on Scott's farm are mostly heirlooms on Antonovka rootstock planted some 30 years ago. Scott did no spraying whatsoever this season. His fruit is amazingly clean but it's not going to have photosynthesis support to get to harvest. And next year's fruit buds will certainly suffer as a result of nutrient flow shutting down.

This evening I've been sent pictures of a smattering of Marssonina found in a cider apple orchard in the western foothills of the Hudson Valley. This ten-acre planting is just down the road from "Angry Orchard" (accordingly I like to kid the brothers involved that their operation must be "Passive Aggressive Orchard") and consists of 2nd and 3rd leaf trees, mostly on Geneva and Bud.9 rootstock, trained to trellis, just starting to bear. Management follows the core holistic program with trace minerals provided in tonic form (Mikronite from Agri-Dynamics). Sap analysis done at the end of the cell division phase revealed the typical need for more calcium, manganese, magnesium, and iron... but this supplementation was not underway in earlier sprays as sap levels looked righteous starting out. Cueva was applied on June 15 to the rows showing what looked like Frog-Eye spotting (with a curious red halo) despite that seeming so unlikely in young trees (and a bit late to have relevant impact). Now those leaves are turning yellow and blotchy, ergo, it's Marssonina making inroads in this planting.

Let me end by pointing out two articles in previous issues of Community Orchardist. An overview of this up and coming fungal disease was provided in the Winter 2020 newsletter. A plausible means of addressing inoculum loading was then suggested by Lou Lego in the Winter 2021 newsletter. Time to zone in again, folks!

Lost Nation Orchard
Zone 4b in New Hampshire

Edited 2 time(s). Last edit at 07/15/2021 07:46PM by Michael Phillips.
Re: Marssonina 2021
July 15, 2021 07:29PM
There's lot of black rot going around and some varieties are obviously more susceptible than others to it. I am not surprised. It starts to get ugly when you CAR and yellowing (maybe Marsoninna , maybe not) starts to creep in. When visually IDing "Marsy" I look for the blotchiness and not just general yellowing. I have seen both this year and with all the rain I am not surprised. But general yellowing is not always Marsy. I am intrigued by Lou's approach to spraying as well as his general approach of cleaning up leaves after each season (more for scab than Marsy). This year I have not yet seen much Marsy, though I expect that will change in the next few weeks. I have also seen some trees with apple mosaic virus that in the early stages could be confused as Marsy. Most of the growers I am working with are using a combo of Double Nickle/Cueva/Regalia/micros as well as other nutrition. Doesn't work so well with CAR or scab, but other diseases including fireblight seem to be kept at bay. We'll see over the next few weeks how the Marsy develops and maybe that helps as well too. What I am 100% sure of is that stopping any spray program too early in the season will result in extensive Marsy. And with this rain, like the cicadas in NJ, it could be biblical. Anyway, lets keep it\\the convo going.

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: Marssonina 2021
July 28, 2021 02:36AM
I've got what looks like Marssonina and am unfamiliar with it in apple trees. We see it out here in Colorado in Aspen, but not so much in apples. I'm reading this and the previous threads to see what if anything I can or should do but would appreciate any experienced eyes taking a look and seeing if you agree. Two of the pics in the folder look strikingly like marssonina, the third from a second graft, less so. Thoughts? And thanks in advance.

Here's the link: Marsonnina

Wheat Ridge, CO, Zone 6a (2018)
Golden, CO, Zone 5b (2018)
Crawford, CO, Zone 6a (1905)
Lewis, CO, Zone 6a (2017)
Re: Marssonina 2021
August 01, 2021 02:44PM
These young trees in pots have yellowing leaves, Jay, but it's not Marssonina. Far more likely nitrogen is running short as the biology in that pot doesn't have reserves to call upon. Irregular watering could be part of this situation. The infection lesions that resemble frog-eye leaf spot early on will coalesce into harder and browner blotches on apple. Perhaps that resembles how Marssonina plays out on aspen, perhaps not. Here I can watch the poplar trees but all appears green in far northern New England to date. We also have not had the deluge conditions growers a couple hundred miles south are experiencing where I first saw signs of blotch in downstate orchards this year.

Lost Nation Orchard
Zone 4b in New Hampshire
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