Uconnladybug's Blog

Promising little baby zucchini or summer squash that decide to turn yellow on one end (the blossom end): what is it?

Young zucchini aborted due to poor pollination. J. Allen photo.

Well, a likely culprit is poor pollination. We experienced this both last summer and again this year, mostly on the earliest fruits to form. Then, when they were only a few inches long, the blossom end turned yellow and began to rot. After researching the problem, it seemed that poor (incomplete) pollination was the problem. A few days later, armed with cotton swabs (a.k.a. Q-tips), we headed out to the garden to attempt to pollinate by hand. When we got there, we found several bees buzzing around in the squash and cucumber flowers so we decided to wait and see if things would improve on their own. They did.
Quite a few zucchinis were successfully harvested and then the plants were lost to Plectosporium blight, a fungal disease. The primary symptom of this disease is white, diamond-shaped spots on the infected stems and sometimes the fruits.

White, diamond-shaped spots on zucchini stems caused by Plectosporium blight. J. Allen photo.

The poor pollination symptom could easily be confused with the disorder known as blossom end rot which is caused by a deficiency of calcium during fruit development. More info on this: http://pender.ces.ncsu.edu/2013/05/why-are-my-squash-rotting/ .
We’ve had a few squash bugs, too, but they haven’t caused much damage. Here are a couple of them mating in the sun on a young butternut squash. Eggs and nymphs were found too! As you can see, for me it’s almost as much fun to find problems in the garden as it is to watch the plants grow and produce a harvest.  By J. Allen.

Squash bugs mating. J. Allen photo.

Squash bug nymphs. Univ. of Minnesota photo.