I have received a number of calls in the past month concerning cross-pollination of different vegetable crops in home gardens.
Most cross-pollination issues are not of huge concern to most home gardeners. A general introduction into how plants are pollinated will give you a better understanding of how your plants produce fruit.
Pollination is the transfer of pollen, either between flowers or within a flower, and is required for many vegetables to produce.
Pollination is not important for plants we grow for leaves, like cabbage or greens, or for plants we grow for their roots, such as carrots and radishes. However, pollination is almost always needed for vegetables that we grow for fruit and seeds.
Pollen is produced in the male parts of the flower (anther) and must be transferred to the female parts (pistil).
Once pollen is transferred, the ovary (a part of the pistil) develops into the fruit or seed that is eaten. Pollen is moved from the anthers to the pistils in different ways.
Pollen from wind-pollinated plants, like corn, falls from the tassel to the silks of the ears. If something is preventing the pollen from being carried by the wind, the result is ears with missing kernels or empty rows.
Corn that is planted in long, single rows loses most of its pollen. It is best to plant corn in blocks rather than in long rows.
Tomatoes, beans and peas are considered self-pollinated because pollen is transferred within individual flowers. Both female and male parts are contained in the same flower.
Insect-pollinated crops include squash, melons, pumpkins and most cucumbers.
They have male and female parts in separate flowers, but both flowers are on the same plant. Insects move pollen between the flowers while collecting nectar and pollen for their consumption. Honeybees and bumblebees are the most common pollinators.
Since bees are often found around the flowers of self-pollinating and insect-pollinated plants, it is important to consider them when selecting when and what time of insecticide to spray.
If possible, choose an insecticide that is the least toxic to bees. Time your sprays later in the day. Bees don't fly around as much during the hotter parts of the day.
Just as with corn, self- and insect-pollinated crops suffer from lack of pollination and fertilization.
Shade, insufficient moisture and high temperatures can cause pollen to behave abnormally. This can cause a lack of fruit development. Incomplete pollination often results in poorly shaped fruits in many vegetables.
Cross-pollination between different vegetables does occur, but it is not of much importance to most gardeners.
Different varieties of the same vegetable may cross, but there is no crossing between different vegetables (cucumbers, melons, squash).
All summer squash, vegetable spaghetti squash, Halloween pumpkins, acorn squash and ornamental gourds are closely related and may cross if planted close together.
However, when they cross, it will not affect this year's crop.
The effects of the cross-pollination will only be seen if you save seed, or if volunteers come up next year. If you do grow several different varieties of summer squash in your garden, it is recommended that you purchase fresh seed every year.
Don't forget to stop by the Dawson County Produce Market beginning Saturday.
The market will be open from 7:30 to 10:30 a.m. every Saturday and Wednesday until late summer at the Agricultural Service Center on Academy Avenue.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.