Perennials forum→Black thumb - Hydrangae

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Name: Derrick
Ohio (Zone 6a)
Swarley
May 5, 2020 4:40 PM CST
This is my first time trying to build up my flower bed so I planted 3 summer crush hydrangaes. However, I'm quickly noticing that the leaves and plant is looking diseased? What should I do to get it back to health?

Thumb of 2020-05-05/Swarley/b27e56
Thumb of 2020-05-05/Swarley/2e7228
Thumb of 2020-05-05/Swarley/ebda20
Thumb of 2020-05-05/Swarley/04877a

Name: Bob
Vernon N.J. (Zone 6a)
Charter ATP Member Bookworm Snakes Plant Database Moderator I was one of the first 300 contributors to the plant database! Forum moderator
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NJBob
May 5, 2020 5:19 PM CST

Moderator

Looks like fungus = this link should help.
https://plantaddicts.com/commo...
The spotting on stems is pretty normal for Hydrangea.
Name: Gary
Wyoming MN (Zone 4a)
hostasmore
May 5, 2020 7:51 PM CST
Welcome to NGA Swarley! Are they newly planted? If so, they may just need some recovery/establishment time.
Name: Derrick
Ohio (Zone 6a)
Swarley
May 5, 2020 8:57 PM CST
hostasmore said:Welcome to NGA Swarley! Are they newly planted? If so, they may just need some recovery/establishment time.


Yes planted about 2 weeks ago. I've read to just trim off the affected leaves, to trying natural remedies, to finding fungicides that have chlorothalonil.

Any suggestions on best approach would be greatly appreciated.
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 7, 2020 3:46 AM CST
Welcome to NGA, Derrick. Here are some comments:

Picture 1:

The plant looks very healthy. The leaf in the center has a leaf spot all by itself. It is a common problem caused by overhead watering (water the soil, never the leaves to minimize the changes of cercospora leaf spot and powdery mildew). The stem looks fine. The brown spots are called lenticels, which act as pores. Some varieties of hydrangeas have more than others. Sometimes they are brown. Other times they are red, purple or almost black.

Picture 2:

The plant still looks healthy. The leaf that you (?) are holding has a few winter damage lesions (probably late frosts as I see that your weather is still hitting a few cold nights now and then) by the leaf tip... those reddish areas. The leaves in the bottom right and top right also show a little reddish color from winter damage too. The large leaf in the right center shows some mechanical damage but nothing to worry about. The stems also display brown lenticels.

Picture 3:

The leaf that you are holding also has winter damage. The reddish zones have turned brown... an opportunistic fungus has arrived. After a while, affected areas that are brown may degrade further and "become" holes. Avoid watering the leaves to minimize fungal problems. Always water the soil and never the leaves. If your sprinkler is getting the leaves wet, consider running this zone close to 6-8am so the leaves do not remain wet for a long time. The leaf in the bottom center that is off focus looks like it got more winter damage still.

Picture 4:

Some more winter damage and lenticels. The leaf on the bottom left corner has some dark spots but I could not tell if they are red, brown or black due to the amount of shade. It may not be a problem. Some of the older stems appear to be more woody and grayish or sandy or brown. Normal. Green looking stems will eventually change that way too in a year or two or so. New stems will definitely be green but when the plant hardens for winter in the Fall, all of the stems will begin to change their color.

So, avoid overwatering to control a few places where there is leaf damage from winter. Do not overwater the plants as this increases the humidity levels and fungi love that. Leaves that fall and any other plant debris can be thrown in the trash, not the compost pile. See if that is sufficient to control the fungus.

I assume the plants are in a location where they get morning sun only, dappled sun or they are in full, but bright, shade.

Monitor the soil pH as one plant is close to some rocks (Picture 4) that may leech lime. If the soil pH becomes alkaline, the leaves will turn light green, then yellow, then white, all this while the leaf veins remain dark green.

As temperatures begin to warm and typically stay above 85F most of the time, increase the amount of water. If they were to typically stay above 95F, increase the amount of water again. As cooler temps arrive in the Fall, reverse this process. As temperatures stay below 95F, reduce the amount of water one notch. As temperatures stay below 85F, reduce the amount of water again to Spring levels. Then, once the plants have gone dormant, reduce watering to once a week or once every two weeks depending on local rains. Once the soil freezes, you can stop watering. Once you observe leaf out in Spring 2021, you can begin watering at Spring levels. Tweak as needed for your conditions which may require even much, much more water than those numbers.

Feel free to use frost cloth or other fabrics to protect the plants from late frosts. These can probably stretch until mid May-ish. See what the average date of last frost for your city is (see below) and, since it is an average, add 1-2 more weeks.

https://plantmaps.com/interact...

The plant in Picture 4 is planted -maybe- too close to those bricks. Since Summer Crush can grow as wide as 3' (max), I wanted to point out that it will extend past the bricks. If there is grass there then no problem but if it is a walkway, it may bother people when walking over there.

Does that help you? Luis
[Last edited by luis_pr - Jul 10, 2020 2:44 PM (+)]
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