Backyard Aquaponics
A place to discuss aquaponics

I think this is blossom end rot on my zucchini. Can someone confirm? I've read this is caused by lack of calcium. I thought I had enough of that. Are there any other causes?

I have some calcium nitrate powder. Anyone know if I can make a foliar spray with that and how much to add to the spray?

I now think my issue might be lack of fertilization since another fruit is now growing quite well on this plant.

However, I don't have alot of experience so I don't know what an unpollinated fruit does or looks like. I have one zucchini, 2 yellow summer squash and 2 pumpkin plants. Since there aren't many plants (and not many flowers), whichever one had a male flower, I tried to pollinate the others. Perhaps they aren't fertile when cross-pollinated(?) Any help, comments?

What's the pH of your water? Usually lack of calcium results in that sort of end rot even if it's available in the water. If you fruit at all then you are successful in your pollination so I don't think that's the issue. High nitrates can cause this due to the plant growing too quick and not able to supply enough calcium to the fruit. Also temp changes can affect this and it's been real hot last couple days here in the DC area...

As eddies has already said,plus Calcium is not very mobile within the plant so this deffiecincy was in place for a while and looking at the leaf you have a Magnessium deffiency as well.As already asked what is the PH of your system ?
Calcium Nitrate will make an excellent Foliar Spray,if you address the Mg issue with Foliar don't mix it with the Calcium as it will precipitate out of solution.
High temps low humidity will give Calcium deficiency in plants,low transpiration caused by this will decrease all nutrient uptake into the plant,Calcium seems to be effected more so.

Thanks for the info. On pollinating, it was done on different days with different flowers from different plants (although I don't remember which, when). Thus my theory that one or more of the plants might not be compatible to cross pollinate.

Ph a steady 7, nitrates 20. No ammonia or nitrite.

I use a bag of eggshells (calcium carbonate) to keep ph steady so I really don't think I have a ca problem but might try the spray. Would too much Ca cause Mg issues? Perhaps I'll add or spray Epsom salts.

Egg shells in the system won't start taking effect until the PH drops 6.8 and lower and excessive Calcium can effect both Potassium and Magnessium uptake.

What's the best way to add calcium and magnesium then?

If your in a position where you have a falling PH,you have a couple of options,you can adjust the PH using Potassium Hydroxide and Calcium Hydroxide,used in equal amounts or my preference would be more Calcium to Potassium,add this until you have the PH level you want,using this method it will require daily checks to ensure the PH is still within the range you want,Magnessium can be added at the same time,Mr Damage uses a ratio of 3-1-.5, Ca- K- mg.
If you want to buffer your PH you can swap The Potassium Hydroxide for Carbonate or Bicarbonate,again following the ratio of 3-1-.5,as in all things AP it's working out what works best for you and your system.
In my system for a long time my PH was at 7.8,I added Potassium Sulphate to the system and Calcium Hydroxide into the MT,the MT water was PH adjusted before it was added back to the system,this was also supplemented with a Foliar regime as with that high a PH nothing was really plant available,everything was working fine until last months heat wave,then I started suffering with a Calcium deficiency that I am still trying to sort out,I think the plants that were here during the heat wave won't improve,hopefully the new starters will have real signs of improvement.
To add it into the system,I like using the vortex MT for the Calcium as it really does get it dissolved well,the rest is placed in a bucket of system water and stirred until dissolved,this is the poured into the outlet of the RFF,so it gets further mixed as it passes through the filters before joining the sump.

Keep what Andreas had to say somewhere that you can find it when you need to do it.

I'd like to see more of this plant. I can tell that it has a deficiency by the light areas between the veins on the leaf but I can't tell whether this is new or old growth and I don't know if this deficiency was present when the damage to the fruit occurred. I need to see where the stems originate and the leaves, preferably in the same picture.

. I suspect this may have a lot to do with the Blossum End Rot. It's also not uncommon for the first fruit to have BER but none of the succeeding ones.

- If this is your first fruit and it's the only one showing this, I'd wait and see what happens.
- If the weather was extra cool or extra hot, I wait and see what happens.

What's the water temp? Post up a couple pics that show more of the plant if you can .

Thank you everyone for the info.

Here are some photos. Some notes:

zucchini in question has a nice fruit on it.
Summer squash just started fruiting. Both have had a few immature fruits fail. All green plants are growing fast except a couple cucumbers and watermelon (see photo).

Strawberries are fruiting. Tomatoes have blossomed. Pumpkins just starting to blossom.

water temperature is just under 80F (25C). May was colder than normal (60s F every day) and it rained nearly every day. The last week or so has been warmer than normal (80s F -- 25-30C).

I'm going to make a separate post/thread on chemistry control--I might rant and extend this post too much.

just posted a note on pH control for my system here:

http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=27332#p537281

Looks like blossom end rot to me.. If so you should have the same issues with squash, melons and Tomatoes.. not certain about the berries. While an acidic media would certainly do that if shot on calcium without bio available calcium the plant can use it will still have blossom end rot. Shells are ok , but not bio available immediately. We used bloodmeal and or crushed oyster shells and it seems to help a lot .. as in BER went totally away. I thought about trying Oscote .. 33% is supposed to be immediately available.. the remainder over time... I did not however .. I'd rather use something more natural .. I'll be interested to see how your turns out .. It's frustrating to have such great looking plants and the fruit have that problem .. In my case I have critters I give bad fruit to so it isn't a total loss.. I'd rather it be me as that is the point I guess.. good luck

Please help.

My pumpkins and squash suddenly wilted and are dying. The end of the vine doesn't appear to be dead yet. The wilting happened in a day. Each plant of four plants a couple days apart. This happened to my pumpkin last year at about this time too. Going along nicely, then suddenly dead.

There are several things that could cause a wilt like this but if I had to guess it's probably a borer or some sort like the squash vine borer.

https://pender.ces.ncsu.edu/2012/05/act-now-to-protect-squash-plants-from-vine-borer/

So I pulled out a couple of mostly-dead squash plants.

The base of the stem was hollow and most of the roots were gone/dead.

Is this consistent with pest or disease?