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Janet Macunovich

Member Since 02 Jan 2012
Offline Last Active Aug 17 2020 10:19 AM
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Posts I've Made

In Topic: Southern blight on hosta

14 July 2020 - 06:55 PM

We have been seeing southern blight, Sclerotium rolfsii for about 15 years in our part of Michigan. Back when, it did not occur much in northern gardens and farm fields but warming climate allowed it to move north. So it's theorized.

 

If the leaves suddenly wilt, brown and die on a hosta in mid-summer, tug on them and see if they are rotted right where they join the crown. If they are, take a look at that bud. If it is dry or deformed, chances are pretty good you are looking at southern blight.

 

It is a fungal disease (Sclerotium rolfsii) that can affect hundreds of plant species and it can reside in the soil. So remove any suspect hosta and destroy it.

https://www.apsnet.org/edcenter/disandpath/fungalbasidio/pdlessons/Pages/SouthernBlight.aspx

 
Remove the hosta, and the soil immediately around it. Discard them as NON-COMPOST because 140F composting temperature does not always kill this fungus. Alternatively, bury the affected plant and soil deeper than size inches. Then plant with something resistant to southern blight. Ornamental grasses and woody plants are the best bet.
 
The bulletin from U of Kentucky (link below) has very good images and clear replanting strategy. So many plants are susceptible - the one fault I find with the UofKY bulletin is the short list of susceptible plants. We usually see the growing points/buds/eyes of hostas with southern blight looking like the UofKY sweet potato example.
 
Janet


 

In Topic: favorite digging fork

13 July 2020 - 08:55 PM

Thank you! We have seen that fork and did wonder if the strap connection would bear up. Now we know - you look like someone who gives tools a serious workout!


In Topic: sickly burning bush branches

13 July 2020 - 08:53 PM

Sorry to say, burning bush does that sometimes - a branch or two will simply up and die mid-season. Not a bacterial blight - it does happen to leaves still growing but they do not blacken and die instantly (as we say of blight "it looks like the wicked witch of the west just zapped them). Instead, the leaves go through color change like you describe, then do not fall but end up brown and dry. Sometimes the next year the whole bush just goes, the same way, mid-season.

 

A fungus that gets into the wood seems to be responsible: Sclerotinia sclerotiorum. (It's sometimes called "White mold", but the appearance that gave it that name is more likely to occur inside tissues when it infects flowers and stems of the hundreds of non-woody plants it can infect.) Sometimes just the couple of branches die back. We used to say dieback from this fungus was closely linked to drought years, perhaps because it is best able to kill already-weakened wood. However, for the soft-tissued plants it affects, 10 days of cool wet weather seems to open the door to infection.

 

More on this disease at https://ipm.illinois...s/rpds/1008.pdf

Since this fungus is most prevalent on herbaceous (soft) plants, much of this very informative bulletin deals with handling the disease or agricultural and floral crops.

 

Prune out the dead wood looking for discolored wood and bark to be sure you cut below all the infected area. Sterilize your saw or loppers after the cut - use bleach or peroxide. If it is a very important plant you may want to follow up next year with a fungicide on the newly-forming leaves and new twigs, since this is when the fungus first invades the wood, when it is new and green.

 

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Sorry to be giving you such a delayed response. We've fallen behind this year. Pandemic lockdown delayed all our April work and we gardeners know April will NOT be held back. So catching up April meant running like heck all May and June to compensate. Now we are mostly back on track outside but most of our administration time has been and still is being taken up by Forum work you do NOT see. We are getting a much needed upgrade and reprogramming to make the Forum simpler to use from cell phones, easier to join, and better able to repel ad-bots. (We spend time every single day kicking out ad-bots that made it partway through to becoming members. Most would fail then and never get past that point but some would get through the last defenses  - it's all a numbers game, bots trying out combination after combination to break security codes. So we kick them out at failsafe #1.) Anyway, we are back now, catching up and enjoying this!


In Topic: Alberta spruce

13 July 2020 - 08:05 PM

Like all spruces, dwarf Alberta spruce is best pruned  as it reaches maximum allowable height or width because it will not regenerate from needle-less wood. You can cut a spruce branch back to its furthest-back side branch that still has needles, then let that space fill in as that twig beefs up, branches and grows out. (Please note that sometimes the very last branch with needles is not productive enough, can't produce on its own enough sugar and starch to keep growing and also provide its branch with all the starch it needs -- leaves keep their branch alive and fed! So we should more accurately say you can cut back to the furthest-back vigorous side branch.)

 

So if you look inside the spruce to see how deep its foliage continues inside the outline, you will know how far you can cut it back.

Most dwarf Albertas (they are a dwarf form of white spruce, Picea glauca 'Conica') have foliage only 3 or 4 inches deep into the tree, so they can only be reduced by 2 to 3 inches. If we start pruning when the branch tips first reach their space limit, we can keep them pretty much indefinitely at that point. We just cannot go in reverse very successfully.

 

So your dwarf Alberta spruce should probably go - unless you want to start pruning it now and enlarge thebed on the lawn side. Prune it by shearing an inch off its exterior, then thinning to let light reach foliage even deeper into the plant. As you thin, cut back to side branches and be sure to remove stubby needle-less tips. It can be tedious or, like weeding a large bed, become a meditation.

 

If this is a summer home and you are looking to screen that window from outside eyes I would replace the spruce with something deciduous, faster, and simpler to keep small. Simpler but requiring pruning every year or two.

 

Rose of sharon (Hibiscus syriacus) comes first to mind. It's fast to grow, and summer blooming on new wood. Let it grow until it is the height the dwarf Alberta is now, then begin cutting it back by 3' every fall or spring as part of cottage close-up or opening. Within 3 or 4 weeks of spring budbreak it will be back up to screen the window. Choose a sterile (seedless) variety such as 'Diana', 'Aphrodite', 'Minerva' or 'Azurri Blue Satin' to avoid the #1 rose of sharon problem, which is its prodigious seed production that leads to hundreds of seedling rose of sharons coming up in beds and lawn all around. (However, if you plant for pollinators and hummingbirds, the sterile rose of sharons are not the best. Their nectar production is low and the configuration of the actual flower parts makes it difficult for pollinators to gather nectar.)

 

Sorry to be so long in replying. We have fallen behind this year because the pandemic lockdowns delayed April work. Spring work can never truly be made up, only compensated by lots of extra May-June work. At the same time we have been devoting the administrative time we have left to upgrading the website including a long-needed revision to this forum to make it simpler to use from cell phones. But as of this week we have spring work covered and are reaching back to catch up on all else!


In Topic: Planting under Norway Maple by Spruce

16 May 2020 - 10:44 PM

You can build the area up - no soil against the tree trunks and I hope you caught Chapter 5 of our Earthwise Soil Prep webinar for the explanation of determining how much of the tree's root zone you will be affecting. If you add soil over an area that's 1/3 or less of the tree's root zone and you guard the other 2/3 from damage you can transform a garden. But you might have unrealistic expectations of the area. With large trees overhead your garden has to be considered the junior partner. That is, plant with the expectation that your  garden will NOT be lush and jam packed. But that doesn't mean it must look thin and poor. Choose your places under the trees to add up to maybe 40% of the space and plant that 40% heavily and with impact. Maybe one central spot has a mass of Japanese painted fern -- good in dryish areas and in some varieties so gray-white in leaf color it looks from a distance like a spotlight in a shady area. And places to right and left of the fern have huge leaf yellow-and-green variegated hostas. Between planted spots leave graceful space in curving-edged chunks or in actual paths with benches or wood sculptures along the way.

I hope this helps!

Janet