Black Spots on Leaves. Cannot identify.

[carolyn137]

Originally Posted by bower

Well, whether there is or isn't a separate concern relative to the Potato Spindle Viroid, the article that seaeagle posted is perfectly clear, that the reasons for the ban in NZ is the concern for human health and the environment.
"“Given the serious effects chlorothalonil can have on human health and the environment, initiating a Red Alert is another way for us to help protect New Zealand and New Zealanders from chemicals that we have concerns about,” says Dr Freeth."

Also I don't know of a ban in Canada, the wiki said that there are high levels of it found in PEI - where potatoes are the main crop - and that some fish kills in PEI had been caused by runoff of the stuff. So the spuds I buy here are likely contaminated with the same residues.

@Carolyn, just browsing I came on this link to "Toxnet" at the NLM. This one really does cite a lot of sources, and covers about everything!
https://toxnet.nlm.nih.gov/cgi-bin/s...rm+@DOCNO+1546

Yes, I have that one already and now will try and explain.

If you look at my initial answer I used the word Daconil and said that came to mind since I had just asked Freda to get some Daconil on my tomato plants.

I did a heck of a lot of Googling last night and here's the best one which explains the life cycle of the viroid and points out that not all infections are lethal, some are mild,and that seeds saved from those fruits can also contain the viroid.

Since I have that link already on my fingers I'll link to it now

https://www.google.com/search?hl=en&...w=1706&bih=815

The important point,I think,is that almost all living entities are susceptible to diseases,although I can't speak to Elephants or crocodiles,etc,and that pathogens in order to infect have to have an attachment site for the susceptible crop,so lets go just with tomatoes now.

I repeat again,as I did in my earlier post above that Daconil has NO effect against any viroids and in doing my Googling I found there were a couple of NEW viroid diseases as well.

So yes, we already know that Daconil,aka Bravo,aka Chlorothalinol,can block sites on the upper leaf surface to help prevent tomato fungal diseases such as Early Blight and Septoria Leaf Spot.

But with regard to the two most common bacterial diseases,Bacterial Speck and Bacterial Spot,it isn't so easy to help prevent. Some have used Actinonvate and, some other products as well.

I'll now link to the results of a couple more of my viroid searches

https://www.google.com/search?q=can+...&bih=815&dpr=1

https://www.google.com/search?q=how+...&bih=815&dpr=1

Carolyn