Tuesday, June 9, 2009

Scourges of Summer

I am grateful for the recent rains here in Chicagoland because they have kept me from having to water the garden, and my new plants, particularly those in the rain garden itself, are benefiting from the frequent moisture. However, this has been a soggier spring than usual, and such conditions portend the arrival of two of the worst summertime scourges--powdery mildew and earwigs.

Both develop and thrive in moist, humid, hot conditions. Powdery mildew absolutely decimated the bee balm (Monarda didyma) I tried to grow a few years ago. I was so traumatized by their hideous demise that I have just this year planted some wild bergamot (M. fistulosa) in the hope that the native monarda species will be more mildew-resistant. The current moisture conditions are challenging this foray back into bee balm.


(Can the wild bergamot outwit the mildew?? Odds aren't good with them laying prostrate on the ground...)

Last year the mildew attacked my smooth blue asters (A. laevis), so already my confidence in the natives' ability to avoid this blight is shaken. I removed some suspicious-looking leaves from the asters last week and am closely monitoring the foliage now. The leaves were browned with some black spots--not the telltale white gunk of powdery mildew--but I'm hypersensitive nonetheless.


(Will this aster be a repeat victim?)

As for the second issue, earwigs, I don't know precisely how much damage these disgusting invaders do to my plants, but I highly doubt they contribute anything positive to our little ecosystem here. In the past they have set up shop in my containers when the potting soil remains moist. As a result, there have been times when I stuck my finger in the pots to check the moisture level and swarms of earwigs crawled out. Needless to say, my screaming and flailing most certainly qualified for some "goofy gardener" behavior, a la Carol/May Dreams Garden.

Let me qualify something here--I'm not anti-insect. I grow plants to actively encourage butterflies, bees, and dragonflies to visit my garden (yes, pretty non-scary bugs, I know). I don't disturb the spiders because I know they're eating other bugs. When I saw the guy below, I didn't run, I took a picture. But until someone provides proof of any benefit from earwigs, I will continue to loathe them and smush them on sight.


(What is this insect, in repose on a leaf of pale purple coneflower? Click the picture for a close-up.)

Regardless of my particular prejudices, our rainy, humid weather encourages various garden pests, so if you live in northern Illinois, be on the look-out. I've tried spraying a baking-soda-dish-soap-water mix on the mildew-covered asters but to no avail. I still won't resort to chemicals. I've tried to follow the "ounce of prevention" maxim by amending the soil to make the plants themselves healthier, and I'll still be removing suspect foliage. Are there other suggestions out there for dealing with powdery mildew? How do you cope with this or other climate-related scourges?

14 comments:

GinaD said...

What is the correct ratio of baking soda, dish soap, and water? I think I had some of that powedery mildew last year but I didn't know what to do about it that didn't involve chemical treatments, so I just kind of did nothing.

rambleonrose said...

It was 1 tbsp baking soda and 1 tbsp dish soap in 1 gallon of water. The problem was that it didn't stop the spread of the mildew. It didn't didn't do any damage to the plants but it didn't really fix the problem either. I'm thinking of spraying it on the asters now, hopefully as prevention because it doesn't seem to work as a cure once the mildew has hit. If you try it, let me know what happens!

Mr. McGregor's Daughter said...

You must not grow Dahlias - if you did, you know exactly how much damage Earwigs can cause. Same thing for Clematis. Mine are perfect & pristine, right now. In a couple of weeks, the blooms will be ragged bits of color hanging by a thread. It's depressing.
Powdery mildew I avoid by seeking out mildew-resistant cultivars, although I don't grow any Monarda. With Phlox paniculata, I thin the stems to allow for more air circulation, which seems to help. I don't spray anything. It's too much trouble. I don't recognize the bug, so I don't know if it's harmful, sorry.

rambleonrose said...

MMG-I am terrified of growing Phlox paniculata since the monarda incident a few years ago, so I haven't even tried! I know 'David' is supposed to be resistant, but I haven't bothered to invest the effort. No I don't grow dahlias, and now I won't plan to! That's too bad about the clematis; I was thinking of trying a species clematis. Are yours cultivars? The bug in the picture just seemed to be lounging on that leaf. I was out there for a while and it wasn't eating the leaf, so I'm guessing it's a benign visitor!

garden girl said...

Earwigs and slugs are my nemesis! Yuk! Both of them eat the hostas here. I grew a lot of dahlias last year, and nothing bothered them - maybe the earwigs were too full on hosta foliage to bother them.

I have powdery mildew on a few things most summers, but so far it hasn't killed anything, just makes stuff look ugly.

rambleonrose said...

GG-Luckily slugs don't seem to be a problem here, at least I haven't found any yet. I'm keeping my fingers crossed...

garden girl said...

Hi again Rose! I was just at Garden Web and found people recommending milk(!) for powdery mildew, blackspot, and other fungal diseases. http://forums.gardenweb.com/forums/load/farnorth/msg0710531027992.html

I googled 'milk powdery mildew' and found a lot of people swearing by milk for all kinds of fungal diseases.

Supposedly it's the lactoferrin in milk that's the active ingredient. Some said skim or whole milk is fine, others said whole is better because the fat makes it stick better. Some said 30% milk to 70% water, mix and spray. Others said 30% milk was too high.

Some people recommended baking soda/water but others said that doesn't work at all.

I might try this milk remedy on my mini roses - they always have blackspot later in the summer, and they really suffer, even though they always seem to manage to come back the next spring.

garden girl said...

hmmm. . . let's try that link again:

http://forums.gardenweb.com/
forums/load/farnorth/
msg0710531027992.html

Part of the link was cut off - I tried putting it on separate lines this time, hopefully the whole URL will show. If not just google milk for powdery mildew and the forum will probably come up.

rambleonrose said...

Thank you so much, Garden Girl!!! This is fabulous! I have no shortage of milk around this place with the little kids, so I am going to try this ASAP! Thanks again, I'll let you know what happens!

Shady Gardener said...

Hi rose! It's a species of Cranefly, but that's all I know! You could go to Bugguide
http://bugguide.net/node/view/15740 and post your photo. They're very helpful over there! :-)

rambleonrose said...

Thank you, SG!

Gail said...

HI Rose... I have read about the use of milk and think that it might be a good thing to try. I do get some powdery mildew..but cut off the disfiguring sections and see if that helps. I have found that in my clay soil, powdery mildew shows up late in the season when the rain is uneven and so is watering....It hasn't been too bad, but I am keeping a recipe handy...I have a lot more monardas this year. (Make sure the plants are well hydrated and then a day later spray with this~~1 heaping tablespoon of baking soda, 1 tablespoon of dormant oil, and ½ teaspoon of insecticidal or dish soap in one gallon of water as a PM spray. recipe is P Allen Smith).

Gail

rambleonrose said...

Thank you, Gail! This is a great recommendation! Last year the asters came down with the mildew late in the season, but my monardas got it fairly early (around this time of year). I am going to try both this and the milk. We are going to have a little experiment here...more on that soon!

Dahlia Grower said...

Interesting post! It looks like a mosquito on top of a leaf. Recently, I found a neat and well-organized selection of dahlia tubers and decided to purchase a bunch. I started growing them in my garden for the first time. They look well and I don't see any pest or unwanted grass beside them. I just hope that this year will be a year for my first full-bloomed dahlia flowers.

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