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Cottony Scale on Miscanthus? or Mealybug?

Posted by claire z6b MA Coastal (My Page) on
Sat, Nov 10, 07 at 17:07

I planted a Miscanthus Malepartus about 2 years ago, but it never did well. Other Miscanthus's are happy in these conditions.

The Malepartus began to flower this fall but the flowers haven't developed well - yesterday I looked closely and the stems are developing dark splotches.

I did some quick searching in this forum and thought that it might be Miscanthus blight, so I went off to a reputable garden center to get some fungicide. I brought a sample of the infected grass with me.

The garden center personnel pulled the sample apart and found a white cottony substance and a beige insect inside. They said it was cottony scale and there was no treatment for ornamental grasses. They suggested I throw out the plant, or try cutting it way down and check it again in the spring. Maybe I'd be lucky and cut the insects off.

I went home and did a search for cottony scale, and a search for Miscanthus Mealybug.

This is what it looked like:

Miscanthus Mealybug

so I'm betting it's the mealybug, not cottony scale.

I'd like to keep the grass if possible, my questions are:

- Is cottony scale common on Miscanthus?

- If this is actually Miscanthus Mealybug, is it reasonable to cut the grass down to a few inches now and drench the soil and plant with imidacloprid in the spring?

The Malepartus is right next to a Miscanthus Little Kitten and several Panicum virgatums, none of which appear to be infected right now.

This clump of grasses is designed to be a wind barrier for a bird feeder, so I'd like to keep it reasonably intact through this winter. I'm in southeastern MA.

Thanks,
Claire


Follow-Up Postings:

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RE RE: Cottony Scale on Miscanthus? or Mealybug?

  • Posted by claire z6b MA Coastal (My Page) on
    Sat, Nov 10, 07 at 17:32

RE cutting it down now rather than in the spring - I know the mealybug is dormant, but we get fierce winter winds here and I don't want the dormant bugs to get blown around into my other miscanthus's (miscanthuses?).

Claire


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RE RE RE: Cottony Scale on Miscanthus? or Mealybug?

  • Posted by claire z6b MA Coastal (My Page) on
    Sun, Nov 11, 07 at 15:05

I decided to cut the grass down now, after a very windy day yesterday. I really don't want to spread the mealybugs to the other grasses.

I then dug out the Bayer's Rose and Flower spray (imidacloprid) I keep for the lily leaf beetles and I poured the stuff over the cut stems. In the spring I'll use the soil drench (it contains fertilizer so I don't want to use it now).

I've never cut miscanthus when it was still mostly green, and I was astonished to see that about half of the stems had a blood red core at the base. The rest were greenish-white. I even checked my fingers to make sure I wasn't bleeding.

Is this normal? or indicative of some other frightening condition?

Claire


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RE: Cottony Scale on Miscanthus? or Mealybug?

I have a miscanthus 'morning light' which I now suspect might have mealy bug.It hasn't grown one bit since I got it this past summer and appears to be stunted. When I pulled of a blade from the crown and split it open, what I found looked like grains of salt, that's the best to describe it. When I searched miscanthus mealy bug, it said they leave "waxy secretions".....what I found just looked like salt....could this be a sign of mealy bug?


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RE: Cottony Scale on Miscanthus? or Mealybug?

Claire ~ I don't have any answers for you but would suggest you post this question over in the "Pests & Diseases" forum (aka Garden Clinic). That forum stays pretty busy. It sounds like you've found your culprit....some of the experts who post in the GC forum should be able to advise you on how to handle the situation. This forum doesn't get much traffic.

I discovered some sort of shield bug/beetle making a home in my Pampass grass recently so I hacked the plant to the ground as a precautionary measure (and to deprive the nasty little critters of their home...they kept flying out at me every time I walked by the grass). However, I live in a warmer zone than you do and Pampass grass is virtually indestructable.....it can take the abuse.

Good Luck
Renee


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RE: Cottony Scale on Miscanthus? or Mealybug?

  • Posted by claire z6b MA Coastal (My Page) on
    Thu, Nov 15, 07 at 10:34

Will do,

Thanks,
Claire


 
 

 

 


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