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San Diego, Ca.

Would it be a bad idea to compost old pumpkin plants that have some powdery mildew on the leaves? Will PM carry over to next year in the soil?

8/27/2005 3:05:10 AM

West Bridgewater /Brockton Ma. USA

Granted I am not one of the experts here , but as a whole sale grower for many years of Prizewinners ...You ALWAYS take last years growth out of the garden and /or field . The fastest way to have a problem is to let last years pest and fungies get a hold in your garden and destroy the new growth of the current year.
JMHO Get it out of the patch and burn it or take it to the dump ...Saves alot of headach and hurt later on
Bill G.

8/27/2005 8:50:08 AM

Montoursville, PA

Agreed.........burn or remove to offsite dump area all diseased material. If not diseased return to the soil. Any small amount, of piggy back, spores will not upset soil ballance. There are always some, of all spores, in your soil. The air is transporting the milldews 24/7 every day this time, of the year.

In reasonably healthy soil the good guys bad guys will ballance with the good holding the bad, in check. This is true, of all living, contents, of your soil.

8/27/2005 10:30:05 AM

Follansbee, Wv

I don't know about San Diego, but PM will not overwinter in the North. Freezing temps kill the spores. The PM in the north is carried to us on the wind from the south. I was in San Diego many years ago in January and February. I never recall it freezing there so you will possibly have a problem with the spores surviving.

8/27/2005 2:43:30 PM

Hilpoltstein, Bavaria, Germany

but I guess my compost pile never freezes all way through all winter. wouldn't the spores be able to overwinter there and be brought back to the patch in the form of compost in spring?

8/27/2005 3:36:26 PM

Follansbee, Wv

I just did some research on the survivability of PM spores. It seems the spores are sensitive to extreme heat as found in compost piles. I read on several sites that temps over 90 can inhibit or even destroy the spores. I would think that composting the diseased leaves would be fine if the pile was properly maintained and reached the optimum 140°F.

8/27/2005 7:20:52 PM

San Diego, Ca.

Thanks for the responses. And thank you Monty for finding that info. I think I will just throw the old growth out in the trash. With as much work as we put into our soil and everything else it's not worth the risk of some of the spores possibly surviving in the compost pile.

8/28/2005 12:40:56 AM

Hilpoltstein, Bavaria, Germany

Thanks Monty!

8/28/2005 4:56:46 AM

Long Island,New York

Do what I do and suffer disease every year. Bag or trailer your leaves and vines to the dump...pay to drop it off...then, in the spring, go back to the town and pickup compost...pay to pick it up.

8/28/2005 8:56:49 AM

Hilpoltstein, Bavaria, Germany

ha! we can at least dump it off for free here, then they make compost but we have to pay for the compost as well!

8/28/2005 9:12:49 AM

Montoursville, PA

Most reading that I have done indicates that 115 -120 degrees will blow out most fungi spores both good and bad in a non-selective action.

The comment I remember Dr. Ingram making or an associate's words, at a seminar, was something like this: Compost held at or near 120 degrees, for five or more days will be largely cleaned, of fungi spores and bacteria unable, to stand the temperature.

From that consideration anaerobic piles, of compost laden with earthworms working the pile will cause the same result without the loss, of bacteria or fungi. The long term anaerobic pile becomes more ballanced at much higher levels of bacteria, fungi and the other living critters up, to earthworms. Therefore you may correctly assume that compost that has been through the body of a worm will become ballanced containing, like your patch soil, some of all good and bad fungi and bacteria plus the other living critters in much greater numbers.

8/28/2005 9:27:33 AM

[email protected]

The air we breathe has more viable PM spores (Erysiphe cichoracearum) than our crop residues. The primary cause of late season PM is infected crops in southern states. Florida Cucumber growers are infected by South America's crops.

Somewhere in the world, there is always a crop infected somewhere. So don't sweat composting a few PM infected leaves.

Like Monty said, proper composting will kill most disease causal pathogens anyway.

8/28/2005 9:27:43 AM

Montoursville, PA

More: Now enter the thought and fact that a light summer mulch while you grow the plant will set up a small but important anaerobic compost layer between the earth and your mulch. Old hay or leaves will best create this effect.
Hay or leaves contain roughly the same value as manure. Some feel it is better because it has not been used by the animal before becoming manure.

Some will ask...well what about the NPK. You will acquire within two or three years all the natural NPK plus trace elements that any patch needs or any plant can use. This includes nitrogen because the plant only uses a small amount, of any form, of nitrogen maintained, within the soil.

When your biological ballance is strong and nicely ballanced your increased strengths, of all parts becomes definately noticable.

Your addition of animal manure and rotting plant life even provides the biological strength, to,reduce or eliminate some stess, from the use, of chemistry that places a definate stress, to the biological condition levels within the soil. Your need for the invasive cides will be reduced if not eliminated. Once you see and basically understand the plus and minus of patch management you will work more diligently, to further reduce the use, of synthetic fertilizers, insecticides and fungicides.

Moving, in this direction, need not be a step back and punt deal. The reduction or elimination, of some treatments or additions may need, to be in steps. One may not be able, to rebuild, to stronger natural conditions as quickly as some advisors may indicate. Yet the basic truths are real. If you want excellent ballance at least the synthetic salt laden fertilizers can be eliminated right now if you have excellent management, of manures,leaves, rotting mulch. cover crop and one or both types, of tea.

8/28/2005 9:49:40 AM

Montoursville, PA

I agree with most, of what has been said about PM composting here. The problem is most, of us, do not have the skill or physical ability or equipment, to manage compost into the higher temperatures. Therefore advisement to burn or haul off may apply depending, on the management of wastes. The American Indian knew that the burning off, of croplands, helped controll disease even if they did not know what the disease was.

8/28/2005 10:08:24 AM

Follansbee, Wv

"From that consideration anaerobic piles, of compost laden with earthworms working the pile will cause the same result without the loss, of bacteria or fungi. The long term anaerobic pile becomes more ballanced at much higher levels of bacteria, fungi and the other living critters up, to earthworms. Therefore you may correctly assume that compost that has been through the body of a worm will become ballanced containing, like your patch soil, some of all good and bad fungi and bacteria plus the other living critters in much greater numbers."---docgipe


Doc are you suggesting that a cool vermi-pile will hold more bacteria than a hot pile? If you are, than I must strongly disagree. The heat in an aerobic compost pile is generated by the bacteria present. It stands to reason that the higher the temp, the more bacteria present. Also, worms cannot eat undecomposed material. They actually eat material that is partially decomposed. The faster you can get your pile broken down, the faster large populations of worms can move in and finish the job. Add to that the destruction of many pathogens including PM, E. Coli and such and the point is clear. Hot composting is better than cold composting. A hot pile will cool in a matter of weeks, allowing the regrowth of beneficial fungi and the re-population of worms. Piles started now and properly maintained will be polluted with worms by the time spring is in full bloom.

I agree that well balanced soil is key to growing anything. I also agree that it takes time and effort to do it. The benefits of an organically balanced soil are, as we both know, well worth the trouble.

We are getting off the track of the original question here though, which was about composting PM infected leaves. After what I have read, I will not hesitate to throw PM infected leaves into my compost piles. I feel confident that my method of composting will roast those PM spores like chestnuts on an open fire.

8/28/2005 10:29:23 AM

Montoursville, PA

I choose, to burn the vines along with the late summer other property trimmings. The spores are toasted, in an hour or so. The ashes consist, of a mere shovel full, or so that goes either directly, on our gardens, or into the compost. No question about the temperature being high enough, to snuff out the spore or other pathegons.

If compost is absolutely finished it is as good as it can be. If the contents are equal but unfinished the same exact good will be created using more time, in your soil.
This transpires as any undigested organic substance yeilds, to the soil, biological content. In either case the object is to get it, in there and keep your patch working 24/7. It more or less takes a month to adjust, to reasonable additions and is why we often advise March tilling or as early as possible when additions are made, in the Spring.

8/28/2005 6:20:41 PM