confused about phi

[sheeshshe]

OK, I am having to spray for early blight for my tomatoes and scab on my squash. not something I wanted to do, but I was about to lose 30 tomato plants so I caved. the blight was moving really fast and fierce. so the packaging talks about phi and some phi's are 4 days some 7 some 0... and I read it but it didn't make sense to me about what exactly it all meant. can someone explain it to me please? Thank you!

[cynthia_h]

Please write exactly what the label says. My acquaintance with the term "phi" is from the field of mathematics, not gardening, so I can't (yet) help on this question.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[TWC015]

the PHI is the preharvest interval.

It means that you should not apply the product within a certain amount of days of harvesting.

I got some ferti-lome brand chlorothalonil and it has this for each crop listed. If you have this and you are using it on tomatoes, then you do not have to worry because the tomato PHI is 0 days.

[cynthia_h]

Aha! Thank you, TWC015.

Who says that punctuation doesn't make a difference?

phi = ø, the Fibonacci ratio (Golden Mean, Golden Ratio, approx. 1.6181818...)

PHI = Pre-Harvest Interval

Note the lower-case vs. upper-case letters.

Cynthia

[sheeshshe]

yes that is what it is. chlorothalonil. it said 0, but I didn't know what it meant from reading it. Sometimes I'm a little slow. I am also using it on squash and I think that said 0 as well. (scab issue).

[The Helpful Gardener]

I would like to point out that [url=https://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC34550]chlorothalonil is a known carcinogen[/url]. Also acutely toxic to fish, and water borne. Perhaps use on food crops should be avoided...

HG

[sheeshshe]

I don't know what else I'm supposed to do!? I don't like using it, I mean I do everything organic, but I was getting ready to lose 30 tomato plants covered in huge tomatoes. It was either fool around with natural methods that probably won't work with a slight chance that they would, or do something about it. I couldn't imagine losing all 30 plants. I would be devastated.

[stella1751]

Sheeshshe, I had early blight on my tomatoes, pretty much unheard of in Wyoming. (I had to look it up; I hadn't a clue what was going on.) However, we had a wet, cold June, and I probably over-watered in July.

I pruned them all, especially removing the foliage up to a height of about a foot, and they are seriously on the mend now. Mine needed better air circulation. It might work for yours. If you have a few you could experiment with, you might give it a try. I saw decided improvement within 48 hours.

[sheeshshe]

THe blight had moved way up the tomatoes and I had to chop off about half the plant. so on the bottom it is high enough that I can crawl under them.

it is still spreading... sigh.....

[rainbowgardener]

So you tried the poison and it isn't working. Now are you ready to try something else?

To start with, if you haven't already, mulch thoroughly. Lay down newspapers or something as a top layer on top of what ever else you mulch with. It will keep soil from splashing up onto the leaves and spreading the disease. Early blight is early because it over-winters in the soil (as opposed to late blight which doesn't and has to move back north from frost free areas).

Things to try for control

baking soda solution (already mentioned to you)
milk solution (50-50 worked great for me last year when my tomatoes got late blight)
3% hydrogen peroxide sprayed directly from the bottle
foliar spray of ACT compost tea
Serenade is a commercial biofungicide

Maybe try a couple different choices on different plants and see what works best.