Rose Diseases - Bacterial and Viral

» CarolWallace - Mark, I'm anticipating your next article, but it's time for me

Mark, I'm anticipating your next article, but it's time for me to rake up all the fallen leaves from the roses that had downy mildew. And I have a question about how to dispose of them.

Composting is obviously not an option. I am reluctant to burn them for fear I merely release the fungus into the air. So the option appears to be to bag them, in which case they will probably end up with all other bagged leaves at the local composting center.

This raises a major worry for me. We use that compost! Last year we brought home three truckloads full. But if the city is composting infected foliage along with the normal tree-clippings and leaf-rakings, doesn't this mean that we're actually bringing trouble into our gardens? Or is a compost center of this magnitude likely to create such heat that the harmful organisms are destroyed? Carol virtually gardening

-- posted by CarolWallace

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» Mark_Whitelaw - Carol, That's a difficult question to answer since we don't k

Carol,

That's a difficult question to answer since we don't know how hot or how large your community compost pile is kept.

For the most part, these fungal spores will be killed if the pile is kept at 190'F/88'C for a period of 24-48 hours. However, that is quite difficult for the home gardener during winter and early spring, and may be difficult for the community composting station unless they maintain a very, very large pile.

My suggestion would be not to use this compost in your garden unless you first sterilize it.

The easiest way to accomplish this is to create several small, wheelbarrow-sized mounds of the compost. Then cover them with *clear* plastic. When temperatures warm in the spring, the plastic cover should heat the pile well over 200'F/93'C; killing not only the fungal spores but the heat-resistant seeds (like tomatoes), as well.

Verify this higher temperature with a compost thermometer available mailorder or at many home improvement centers. If it fails to heat up, toss in some green matter (like lettuce or cabbage leaves), a cup of water, and a handful of a nitrogen source (like feather meal, alfalfa meal or left over lawn fertilizer). Once the pile heats up, insure the temps remain above 200'F for at least 24 hours. (It should spike in temperature about 10 days after adding the nitrogen source.) After this sterilization, the compost should be safe to use in your garden.

Good question. Thanx for asking it, Carol.

MarkW>Ft. Worth, TX/Zn 7b, Rose Garden

-- posted by Mark_Whitelaw

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