Thank you for considering my questions,

Audrey

Here's the link to the above mentioned site:

http://www.gardentoad.com/companionplants.html

Judith

Only if all fungus diseases are physiologically alike. Since they aren't, this isn't necessarily an odd notion. I have no idea if it works, but I could imagine it to be possible.

Tobacco does nothing to keep away tobacco insect pests, but the leaves contain nicotine which is a known insecticide and tobacco dust does sometimes work as an insect repellent for that reason. (It's just that it's also a risky one to use since tobacco dust can have viable plant viruses in it that sometimes are capable of infecting the plants you dust.)

Many of these "passed down through the generations procedures" were passed down because they had some basis.

Research is now underway to determine how roses fight blackspot. Here is the abstract of one such paper:

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TC3-454758R-8&_user=5460004&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000062861&_version=1&_urlVersion=0&_userid=5460004&md5=35a2d3373e3b4dfce464967c6ff461c6

Tomato is not mentioned in the abstract; however, in the Discussion section of the full paper, the following appears:

(2D-PAGE analysis of ICF extract from blackspot-infected leaves revealed that the pathogen-induced proteins have acidic pIs. In tobacco, acidic PR proteins accumulate extracellularly while basic PR proteins accumulate intracellularly in the vacuole ([Bol et al., 1990], [Linthorst, 1991] and [White and Antoniw, 1991]). It seems that rose extracellular PR proteins are similar to those of tobacco. However, some basic tomato and potato PR proteins were found to accumulate in the intercellular spaces of leaves as well ([Linthorst, 1991] and [White and Antoniw, 1991])."

What "may" be happening is that some of the tomato leaf PR proteins are helping "fight" the blackspot.

As to why it is not done by everyone, the following link describes a procedure (to me it sounds like too much effort):
http://www.ehow.com/how_4904207_of-black-spot-roses-naturally.html

The question that occurred to me, and which she did not address, was whether the neighbor was spraying Dithane or Manzate on the tomatoes and accidentally on the roses. Most people seriously growing tomatoes in blackspot country at that time sprayed their tomatoes.

I can't rule out the possibility that tomato extract prevents blackspot, any more than I can rule out vanilla ice cream. But I've not seen a shred of evidence that it works. Somebody do a contolled test and let's see the spot count.

Somebody do a contolled test and let's see the spot count.

Yes, exactly! Roses have been getting black spot for a century at least. If something as simple as ground tomato leaves prevented it, it would be as commonly used as asprin. But it's not.

It might have some pesticide or repellant properties, since tomatos are in the nightshade family. Tomato leaves and stems are poisonous. They contain an alkaloid that interferes with cholinergic nerves and cause some serious gastrointestinal distress. So make sure you clean your blender out thoroughly lest you poison yourself.

TRUTH!!! Nicotine sulfate is extremely & acutely poisonous to humans!

I completely understand the logic of this (& agree that it appears to make sense); I also have very real doubts for that reason; yet on the other hand, when was the ridiculously simple Cornell mixture for powdery mildew tested and announced?

The spray oil component of Cornell mixture has been long used for powdery mildew. The link gives a history of sodium bicarbonate as a fungicide. It begins with a Russian plant pathologist before 1933 and was supported by scientific research in the early 1980s before Dr. Kenneth Horst combined it with oil a generation ago. Baking soda has been vetted by science and is not a folklore item.

I should add that Cornell mixture is highly effective against PM but does not do much to control blackspot in my garden.

On a side note, I wound up throwing most of the tomatoes and plants in the compost pile. So of course the next year I had many 'compost tomatoes' pop up around my roses because I used the compost. I sort of let some of them stay, but they didn't do anything to prevent black spot.

In 1877 a tomato leaf spray was reported to work for aphids on roses.

Title: The Year-book of facts in science and art
By John Timbs
Published by Simpkin, Marshall, and Co., 1877

This effect is consistent with Hoovb's statement (I have reproduced his total statement, as the warning part I feel is important not just with a blender, but also if one selected to spray the mixture.):

"It might have some pesticide or repellant properties, since tomatos are in the nightshade family. Tomato leaves and stems are poisonous. They contain an alkaloid that interferes with cholinergic nerves and cause some serious gastrointestinal distress. So make sure you clean your blender out thoroughly lest you poison yourself."

If you want to avoid synthetic chemicals, the best bet is sulfur. See the FAQ on the Organic Roses Forum.

I should probably put this in a new message, maybe I will,can you tell me if many of your EAT your Rose Petals? On cakes? In Salad?

Thanks
Audrey

I have roses, tomatoes, clematis, yarrow, marigold, basil, oregano, chives, onions, parsley, and dahlias in the same bed. It looks interesting, actually, and all more or less appreciate the same conditions. I also tucked in some petunias here and there since they were laying around lol!

As to the tomato effect on roses, I think it isn't tomatoes per se, but members of the Solanacea family (petunias, tomato, potato, etc.) that have the effect. I just get tired of "planning" a vegetable garden and having something perform sub-standard when a perfectly good location (next to the roses) would be more ideal.

This is a new method of gardenning - planting fruits, flowers, veggies here and there, based on growing needs and not so much where they belong in the yard - and I kind of like the look.