I think your zucchini is gone lesson learned and if you have an open spot there is plenty of time to get a new one going maybe even dig out that square foot and refill

Aww, I was afraid of that. Just for the hell of it, I think I'm gonna buy a thing of lemon juice and throw some of that into the soil daily. Maybe that'll be enough of a crutch until the sulfur starts its magic.

Thanks for the response!

When is this "Blossom End Rot" occuring. Often I find people assume lack of pollination is BER of squash. Often I also find people assume if their squash or tomatoes do have Blossom End Rot, which shows up in fairly mature fruit, it must be a lack of soil calcium when the soil may have adeqaute levels but other problems caused a deficiency.
Some things that can cause BER are, inadequate levels of soil moisture that keeps this nutrient from moving thru the plant, a sudden growth spurt of the plant with blossoming and fruit set and calcium is too slow moving there, a nutrient imbalance the prevents a plant from properly utilizing other nutrients.

Oops, sorry to hear about this. In general it's best not to try to adjust pH while plants are actually growing in the soil... :-]

I usually see it on the first couple of tomatoes and peppers, then it goes away. I've heard Epsom salts will work, supposedly because it's related to a magnesium deficiency. They are also pH-neutral.

But if it's a nutrient deficiency I have to wonder why it only affects a few at the beginning of the season and then goes away.

Vinegar would work too and probably cheaper than lime juice. You could dilute a bit (maybe a quarter cup or less) in a bucket of water and use for watering, for a few weeks.

kimmsr, You may be right. I just looked for pictures of what I was seeing on the fruits, and figured it was probably blossom end rot. The SFG book suggests using 5 types of compost, and I could only find two, so I quickly jumped on the problem of having a nutrient deficiency. But having only one zucchini plant, now I could see it being lack of pollination. I'll certainly get a professional soil test this fall and figure out if I should just dump out my box and start over or try to amend it.

toxcrusadr, haha, yeah, lesson learned. vinegar sounds like a better idea -- I'm about outta lime juice. Surprisingly, I think my efforts are actually helping a little -- The leaves that are still attached are looking a little greener, and less rolled up.

The liquid acid certainly isn't lasting very long though -- Each morning the pH meter reports that the level is back up. Think some ascorbic or citric acid powder would work better? I don't mind the extra work -- just curious.

Thanks, guys!

If you knew exactly how much lime you put in a certain area, it is not too difficult to calculate the amount of a given acidic substance required to neutralize it.

If the blossoms are dropping off without setting fruit, although the fruit may grow a little bit, it is because of lack of pollination. Blossom End Rot usually does not show up until the fruit is fairly large and the blossom end gets a big rotten area.

You can leach out some of that lime by heavy watering, that will carry it down into the soil a ways.

If you have an accurate pH meter, mix some acid into a 5 gallon pail of water until the pH is lowered to 4.5, use this solution to water the affected plant. The best acid for this application is sulfuric acid which can be purchased at Lowe's for $10 and is labeled as sulfuric acid "Drain Opener", sold in a plastic bottle covered in a plastic bag.

You could also use aluminum sulfate powder if you don't want to handle acid.

dirtydan's method will work but I suspect that with unbuffered fresh water, it will only take a teaspoon of sulfuric acid to drive it down to 4.

Sulfuric is also a very strong acid, which could have more violent effects on plant roots and microbes until it's neutralized, whereas vinegar is a weak acid that might be a little more friendly. They will both get to the same place eventually.

How well does your soil drain? If it drains well, I'd add plenty of vinegar and then flush it with water. Test pH again. If the calcium acetate is not washed away, microbes will metabolize it and the pH will rise again. If you have heavy clay and don't want to flush, use iron sulfate. Elemental sulfur is slow acting.

PS: You will need approximately 24x the weight of 5% vinegar to neutralize 1x the weight of calcium carbonate.

Clarification: when I said 5% vinegar, I meant 5% acetic acid. i.e. full strength food grade white vinegar. A gallon of it will neutralize about 6 oz of lime.