Interval between spraying Daconil and Blossom End Rot Spray

opus743August 2, 2010

Hi folks,

I have been gardening for 30+ years and this is my worst year ever. I got back from Afghanistan in late April and got everything planted late. My plants were thriving in May (cool evenings and good rain) by june the high heat and lack of rain set in. For July we went into drought mode for 10-14 day periods followed by 2-3 days of torrential downpours. So you already know the blossom end rot kicked in and the humid nights which followed caused some form of fungal problem, most likely a blight.

I spray my tomatoes with a blossom end rot preventer after each heavy period of rain not to exceed 2x per month. Tonight I sprayed a generic Daconil (Clorathalonil) as a multi disease treatment. 2 questions:

1. what is the recommended interval I should wait befor spraying blossom end rot spray again?


2. what is the preharvest interval for daconil?

If it matters to the reader, my varieties are:

Opalka (on the verge of dying)

Roma VF (holding their own)

Big Boy (early stages of blight)

Celebrity (holding their own too)

Look forward to some great replies; thanks for your time

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jean001(z8aPortland, OR)

The label will tell you the preharvest interval for daconil. It's sometimes abbreviated as PHI.

As for blossom end root, sprays don't help, but consistent soil moisture will.

    Bookmark   August 3, 2010 at 1:45AM
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appreciate the reply. I am using a generic Cloratholinil (sic) the label does not show a PHI. I am more concerned about how long of a wait before I can spray with CaCl solution which, down here in the sandhills works very well as long as you use it regular yet sparingly. Thanks again for your time

    Bookmark   August 3, 2010 at 6:44PM
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torquill(z9/sunset15 CA)

Cholorothalonil has a PHI of 0 (that's zero) days when applied to tomatoes, according to the University of Wisconsin.

I don't know of any interaction between chlorothalonil and CaCl, so I suspect you can spray both in the same day (wait a half day to make sure the spray is fully dry). Given that chlorothalonil acts as a barrier, I'd spray the CaCl first.

I've never heard of calcium chloride actually having any effect against BER, but if that's your program and it seems to give results, more power to you.


    Bookmark   August 10, 2010 at 2:15AM
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