Friday, July 10, 2009

Experiment Update

I don't have indisputable results yet, let me be clear about that up front. But I am seeing some differences between my asters that underwent the milk solution/dormant oil experiment (full details in this link). Click on any photo for a closer look.


Here is the smooth blue aster (Symphyotrichum laevis) sprayed with the dormant oil solution. Unfortunately, it still has these brown spots that are spreading to newer leaves. However, this doesn't appear to be powdery mildew, so I guess that's a positive, but this plant is definitely struggling. It's also still a snack for the local rabbit, which is apparently enjoying the soapy vinaigrette.


Here is the aster sprayed with the milk solution. The white cast is dried milk, not mildew. So far the discolorations on the lowers leaves haven't spread to more foliage.

Since neither of these plants are dealing with an out-and-out mildew infection, it's impossible for me to say definitively whether milk or the dormant oil is the better fungicide. But the milk solution does seem to be keeping the plant healthier than the oil, at this point. I must admit, however, that the control aster is doing the best of all:


Results are even less clear with the monardas. Here's one:


And the other:


Can you tell a difference? I couldn't either! (For the record the first one had the milk and the second had the dormant oil.) Neither has powdery mildew or any other noticeable fungal infection, so that's great! I guess both solutions are working equally in that regard. But both of these monardas are being chewed relentlessly by insects, and neither solution is helping that problem. I suppose that's why "dormant oil" is meant to be applied when a plant is dormant!

Here's a look at one of the control monardas. As you can see, it looks just like the others.


I will probably apply another round of my solutions this week because we've had more cool rainy weather (what a shock!). I'll keep you posted on more developments, and I hope everyone has a great weekend!

4 comments:

Mr. McGregor's Daughter said...

I have to laugh that the control Aster is the one doing the best. Just to make you a bit more confused, I suppose.
BTW - my Astilbes were looking great until just the last few days. I think the rain came just in time to save the blooms from completely browning out at the top.

Rose said...

Hmmm, Rose, you may have to apply for more grant money to continue this experiment further:) I guess it just goes to show that nature will do what it will and sometimes completely bewilder us gardeners. With all the rain we've had, I think insects are going to be more of a problem this year. I picked off a bunch of Japanese beetles yesterday morning, and the mosquitoes are driving me inside in the evening.

garden girl said...

Hi Rose, thanks for the update. Our cool, wet weather may be contributing to the absence of fungal diseases this summer. There are no signs of powdery mildew or black spot on any of the usual suspects in my garden this season. I haven't seen it in clients' gardens either.

rambleonrose said...

MMG--Isn't that a kick in the pants about the control aster?! I think it shows that no fungicide/insecticide/etc. can substitute for a healthy plant.

Rose--I certainly do need that grant money! :) The bugs are definitely the biggest issue this summer. The beetles arrived here this week and the mosquitoes are insatiable!

GG--I guess I should be happy about the lack of mildew! Of course, the year I gather information and tips and conduct a nice little experiment, there's no mildew. Mother Nature's sense of humor, I suppose!

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