Sunburn or sick

[Sillywabbitz]

I have had this hydrangea for a few years. This year it has recently gotten terrible brown spots and is getting tall and woody.

Is this a fungus or just sun damage.

[luis_pr]

Uneven watering makes the leaves dry out when the soil is dry and you end with stems with just a few or no leaves. Depending on how long your growing season is, the plant may grow new leaves now or in the Spring. And for sure, it will wait until summer temperatures moderate.

The brown leaf spots are a common fungal infection called leaf spot or Cercospora Leaf Spot. It is caused by overhead watering. There is no cure but most people handle the problem using good "clean housekeeping practices". Start by watering the soil -never the leaves- early in the mornings. Dispose of plant debris in the trash since the leaves and blooms can contain fungi. Remember this when the shrubs finally go dormant in the Fall.

You can apply fungicides in cases of a big infestation and the link below gives the names of fungicides for controlling leaf spot. I have this issue in selected shrubs planted in the ground and control it by using drip irrigation and limiting the overhead watering to the hottest periods of the summer. If I see a leaf with 1/4 to 1/3 of its surface covered by leaf spots, I will consider cutting it off and throwing it in the trash. The problem usually becomes obvious as the summer winds down and Fall starts.

Here is more information:

http://www.aces.edu/pubs/docs/A/ANR-1212/ANR-1212.pdf

The brown stem spots resemble color changes that I have noticed on some of my mophead and lacecap hydrangea stems at this time of the year. I assume that they are part of the natural process of hardening in preparation for winter but, you should keep an eye for other symptoms just in case. There are certain types of root rot and bacterial infections that can produce similar symptoms; they are rare though. At this point, I do not "see" anything that would have raised a red flag for me.

You can prune dried out looking stems if they have not leafed out by mid-to-late May.

Luis

[Sillywabbitz]

Thank you so much. I use a drip system and don't water from above. We had crazy heavy rains in the early summer. I'll look into the fungicide. There arelots of new growth on the stems so hopefully it will do ok. Thanks again.

[luis_pr]

Good, I use drip too, except in mid Summer when our daily 100s force me to water manually once a week . It helps control the problem.

[Sillywabbitz]

I'll add in the manual watering one a week:)

[luis_pr]

Depending where you are located, you may not need to (if your summer is not bad). I just 'have to' because temps start hitting over 100 daily in July thru late August or September. Under those extreme conditions, the small roots in the top 4" do not get enough water from the drip (a sprinkler spray would be better) so, as soon as I start noticing leaf wilting in the summer, I know I will have to make sure they still have 3-4" of mulch and I also know I will have to manually water on Sunday mornings. Ugh...