i have been growing some summer squash, and all i have been getting is flowers and no fruit , what can be the problem?
Multnomah County Oregon
Thank you for contacting Ask an Expert in regards to your summer squash not setting fruit. There are basically two reasons why your plant would bloom and not produce fruit: Firstly, and most likely, is the lack of pollination. Secondly, root knot nematodes which are microscopic roundworms. They may be feeding on the roots and this would keep the plant from producing fruit or stunt the size of developing squash.
All squash plants are monoecious, meaning they have both male and female flowers on the same plant. It is the male flowers which pollinate the female flowers and it is only the female flowers that develop into squash. There are usually three to four male flowers to each female flower. You can easily identify the female flowers which are swollen at the end of the stem where it junctions just below the flower base, this is where the squash develops if successfully pollinated. Early in the season, it is mostly, if not all male flowers, so at this time many flowers will die off with no production of fruit.
When both types of bloom open at the same time but no fruit develops, the issue may be a lack of pollination. Unlike self-pollinating plants, the pollen on squash needs to be transferred from the male flower to the female. Each flower is only fertile or has viable pollen for a few hours the first day it opens. Bees or other pollinators must visit both male and female flower during that time for squash to develop.
If you use row covers, remove them before flowers start to bloom; stop the application of insecticides when flowers are open; planting early spring flowering annuals nearby helps to attract pollinators. If all this fails you may want to give a try at hand-pollinating open blossoms. There are two easy techniques to doing this to which I refer you to this web page for complete instructions.
Root knot nematodes, microscopic roundworms, may feed on the roots and keep the plant from producing fruit or stunt the size of developing squash. Dig up a plant that seems to be affected by nematodes to confirm that the little worms are the cause of a poor harvest. Squash plants infested with nematodes have roots covered with swollen lumps. The plants don't recover, but by removing the plants and leaving the area unplanted for a season or covering moist soil with clear plastic for four to six weeks to solarize it, you can eliminate the nematodes for future plantings. Keeping planting areas clean of plant debris and rotating crops can prevent future nematode invasions.
Should you need further assistance you can either ask a new question and one of my colleagues will respond or if you prefer you may reply back to this message to correspond with me. Again, thank you for contacting Cooperative Extension Ask an Expert.