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Garden Q&A

Question: For the last three years, I have had a devastating problem with rose midges. I have used the sprays and soaps (Bayer) that are out there and have found little or no help from them. They are expensive and need to be applied many times with minimal results.

I have also been regularly trimming off the infected areas. All I get is bald bushes, and any new growth is black within a week.

Last year, I read on the Internet that securing wet newspaper at the base of each bush would break the cycle that the rose midges need to survive. This worked! However, it looks horrible. Do you have any better suggestions?

- Pam Babin
Answer: So, you have a technique that worked. Perhaps brown paper bags (which fall in the soil-color zone of the spectrum) would be less objectionable.

Rose midge is a minute insect with a remarkably short life span - 10 days to two weeks. They pupate in the soil; the female fly mates and lays eggs in the tiny tips of new growth; the emerging larvae eat the new growth, preventing flowers. Having ruined your rose, they return to the ground to pupate and repeat the evil cycle.

It is at emergence from pupation that the wet newspapers do their trick - the tiny flies are prevented from mating and laying eggs.

I am not a rosarian, so I spoke with Harry Tyson, one of the "consulting rosarians" of the Philadelphia Rose Society. (Go to http://philadelphiarosesociety.org and click on "Consulting Rosarians" for a list.) In addition, the Pittsburgh Rose Society has a very informative article on rose midge at www.pghrosesociety.org/rosemidge.html.

The consensus among Rose Society folks is that a Bayer product containing cyfluthrin is the best option. Tyson is a fan of PowerForce Multi-Insect Killer and says it should be used as a foliar spray now and at least once a month through the growing season.

Given the life cycle of rose midge, that may not be often enough. He calculated that he can spray more than 400 bushes with one container of the concentrated form (mixed with water before spraying) and considers it a cheap, successful remedy for what can be a big problem.

Cyfluthrin gets moderate to not-enough-info-yet assessments on toxicity and the like from the Pesticide Action Network (see www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC33504).

Another approach is a soil drench using imidacloprid, commonly available as Merit, also a Bayer product. The Internet abounds in suggestions for using different imidacloprid products (such as grub-control formulations) for insects not listed on the labels. I haven't tried these tactics, so I cannot vouch for them.

Q: I have a Melody New York aster, which grows 18 to 24 inches. Is it possible to pinch this variety of aster back like mums, so it will not grow as tall?

- Charlotte
A: Definitely. Pinch hybrid asters just as you would a mum - several times. Time the successive pinchings by examining the new growth; it should have enough new leaves such that, when you pinch the tip off, three or four remain. New growth emerges from the leaf nodes. The last pinching should be around July 4.

Not only will your aster be shorter than without pinching, it will have eight to 10 times as many blossoms.

That can make it top-heavy come September, so you may need to use some supports - stakes with thick string to encircle the plant or peastakes, which are branches from shrub trimmings that you stick into the ground close around a plant before it needs staking. The aster grows "into" the peastakes, hiding them in the course of getting support.


Send questions to Michael Martin Mills, The Inquirer, Box 41705, Philadelphia 19101 or gardenqanda@earthlink.net. Please include locale. Read his recent work at http://go. philly.com/michaelmartinmills.

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