Mary’s pumpkin vines have produced some good fruits but a lot of pumpkins get black spots, shrivel up and rot while they are still small. Other vines have had very few or no female flowers, and she is puzzled as to the cause of these problems.
The squash family can also suffer from ‘blossom end rot’, where black spots form on the fruit opposite the stem – but this is more common on watermelons. A combination of factors causes this common problem of shriveling of immature fruits in plants of the squash family. Click here:
Squash melon and cucumber problems.
An application of seaweed extract ‘tea’ can also help by strengthening cell walls, and helping to reduce plant stress.
Pumpkin vines make an enormous amount of growth for one set of roots, and plants will only mature the number of fruits that the root system can support. You can help avoid problems by encouraging the growth of auxiliary roots. See: Assisting root growth
If plants are not producing female flowers, nip the end off the long runners. Some varieties of pumpkins and melons tend to produce female flowers on side shoots. The cause of this is ‘apical dominance’ where the main shoot of some species of plants produces a strong hormone that deters the growth of side shoots. When the tip of this shoot is removed, growth is stimulated in the buds that form side shoots.