Squash plant flowers withering

Asked July 7, 2016, 10:41 AM EDT

I have some zucchini and yellow squash plants, the plants are very healthy and have produced squash but some of my flowers on the plant do very well then start to wither up and die. Any thoughts or suggestions on that?

Pima County Arizona horticulture vegetable gardening

1 Response

The problem is lack of pollination, thus lack of fertilizations. The flowers develop, but without pollination then fertilizations the young fruit will wither and abort. Several things can cause lack of pollination:

1) No bees to transfer the pollen from the male flowers (the ones with the stem behind the petals) to the female flowers (the ones with the fruit behind the petals). No transfer of pollen = no fertilization = no fruit set.

2) No male blooms. Squash and all the cucurbit family members set male and female blooms on the same plant, but sometimes you will get an abundance of male blooms and no female blooms (which occurs early in the season) and sometimes you will get female blooms and no male blooms (which occurs late in the season).

3) When temperatures are above 85 degrees F the pollen dies quickly, therefore pollination & fertilization does not occur.

To remedy these issues you could simply pollinated each female bloom manually by transferring pollen from the male bloom to the female bloom. Early in the morning before temperatures reach 85 degrees F. seek and pick the male blooms (the ones with the stem behind the petals); carefully remove the petals by tearing them off at the base to expose the pollen sacks; and then jiggle the pollen sacks onto the stigma of the female flower. You will notice how easily the pollen will stick onto the stigma. Fertilization will follow quickly on its own.

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