Question
I'm a rather experienced gardener, i've been doing it for 40 years now.  I grow exclusively heirloom and GMO free seeds.  I have a problem with my squash this year that i've never encountered before.  The plants themselves look great. Very healthy and no signs of disease.  I grow several varieties of squash and each one grows up its own trellis made from bamboo stakes and netting.  They grow up rather than on the ground.  The blossoms look good and dont ever fall off before being pollunated and forming fruit.  Since I have several bee attracting flowers and bushes, my garden is loaded with bees and pollination is definately not an issue.  My plants are LOADED with bees and the pollination rate is near 100%.  All was well until a month ago when I noticed that some of the mature, ready to pick squash and some of the baby squash began to rot on the vine. By rot I mean the growth stopped and the squash turned brown and mushy and totally soft.  It happened on every squash variety in my garden (10 varieties) and it wasn't limited to young squash - even those fully developed and ready to pick began to rapidly rot.  At this point, everything is ruined.  The plants still look good, but as soon as the blossom produces a squash that is 1 or 2" long, it rots vs. growing.  Not just the end - the entire veggie rots.  I planted several winter squash varieties that were full size and ripening off and now those full size squash are mush; just liquid inside.  I had one plant attacked by vine borers, but was able to cut the stem, find the borer and save the plant.  I had also seen beginning signs of powdery mildew and immediately stopped it with a copper fungicide made for organic gardens.  I dont use ANY chemical fertilizers.  My watering system is drip irrigation on a timer and i'm sure the plants were ot overwatered.  even with 40 years of experience,i'm baffled by this one.  They all grow up and dont touch the ground so its not mut rot or rot from being wet.  It's attacking fully grown fully mature squash veggies. as well as those just forming, so its not blossom end rot.  It began suddenly and attacked every variety of squash at the same time.  I'm growing an heirloom 'jumbo pink banana squash' which are known to set records in size.  I had some in excess of 30 pounds each and they also turned to mush, rapidly.  For fertilizer, i use rabbit manure from my own rabbits, comfrey leaves, fish emulsion, seaweed immulsion and some compost and rotting organic material from my vermicompost pile.
What is going on?

Answer
Hi Lisa,

I think there are three potential reasons for the problem with your squash.

The first possibility is low calcium.  If you have not had a recent soil test, you may want to have one done.  Otherwise, you may want to add a little calcium to the soil to see if it helps improve the problem.  This web link will tell you sources of organic calcium (as well as other nutrients).  Limestone will be a little faster acting than egg shells, so you may want to select this option.
http://www.commongroundinpaloalto.org/fertilizers.htm#Calcium

Another possibility is high humidity causing the fruits to rot.  It's great that you are not overwatering, but high humidity can also be a problem.  If it is possible to open up the canopy this is one option.  Otherwise, perhpas you can time your watering so that it is in mid-morning, this way the humidity will be reduced more rapidly than watering late in the day or in the middle of the night.  This may also help with the problem.

Lastly, the main reason is due to pollination problems.  Even if the bees are present, if the there is high humidity or moisture, the plants will be less effectively pollinated.  If there is rainy weather, insect activity will be reduced so pollination is less successful.  You could try to do some hand pollination by removing a mail flower and rubbing it against a female flower.  Some growers I have worked with have had very good luck with this practice.

Good luck with your plants.
--Jen