Squashes and pumpkins are among the few foods considered to be native to North America and they were used by the Indians before the coming of the European settlers. They are nutritious, with many valuable uses for both fresh eating and storage. Proper variety selection and planting produce squash for the table from mid-summer until the following spring. Squashes represent three distinct and diverse groups of plants, but home gardeners divide them into two groups, summer and winter squashes. Summer squashes are eaten in the immature stage while the rind is still soft. Winter squashes are eaten only after the fruits mature. The mature size of squash may vary from several ounces to giant squashes that weigh in excess of 700 pounds.
Like all other vegetables, they are subject to problems. One of the greatest drawbacks to good squash production in home gardens is competition. Squash is a very poor competitor and will not compete with weeds or other squash. If squashes are small and unproductive, they are crowded too close together. Allow plenty of room to develop size according to the variety. Large plants required spacing of 10 x 10 feet or even more. Squash produce longer if fertilized every four to six weeks and given adequate water.Another common complaint is wilt or die-back of squash. Squash wilt is often blamed on squash bugs. These dark brown, hard-bodied, narrow shield-shape insects are 2/3 inch long, 1/4 inch wide, with well-developed wings. They lay clusters of shiny, oval yellow eggs on the underside of the leaves. The newly hatched bugs, or nymphs, are green, soft-bodied and wingless. In later stages, they turn grey, develop wings and exude a putrid odor if crushed.
Do squash bugs really cause that much damage? According to Dr. Sherm Thomson, USU Extension plant pathologist, the problem with squash dying is wilt disease not due to squash bugs. Squash bugs are attracted to wilt-affected plants and appear in great numbers. If they still bother you and you want to control them, Sabadilla is a good organic insecticide, but the price tag may scare you off. Hand picking and destroying the pest is unpleasant but very effective. Crush the eggs when they first appear to reduce the numbers. Thiodan spray or dust will help control the pest.
Squash wilt is caused by a fungus that grows in the vascular system and causes the plant to wilt and collapse. Early symptoms include wilting leaves and eventually the entire plant wilts and dies. The vascular tissue is streaked dark yellow or brown and a soft, mushy rot occurs near the soil surface and a white or pink growth may appear near the soil line. Control is obtained by crop rotation and use of resistant varieties. Avoid wide fluctuations in soil moisture. Do not stress the plants for water and then soak them up. Irrigation should be put on the field for not more than two hours at a time. Yellow crook neck, straight neck and banana squash are very susceptible to wilt and no variety is totally immune.
As nights get cooler and more humid, powdery mildew appears on most vine crops. Mildew leaves the familiar white powdery growth. At this time of the year, it is not economically feasible to control the disease. The problem won't go away on its own, but is not serious enough to affect production before frost. The following varieties are powdery mildew resistant: zucchini select, butternut, crook neck and early summer prolific.
Squash is also susceptible to a wide variety of fruit rots, caused by many different fungi. Rather than worrying about all of the names and causal organisms, control them using good cultural practices. Light, frequent sprinkling increases fungal diseases. Squashes that remain on the plant for long periods benefit from being set on a board or a brick. This keeps them off the wet soil and keeps rot from penetrating the rind. Avoid damage to the skin because it is the best natural defense against fungal diseases. Don't allow the squash fruits to develop in the irrigation furrow. Irrigation waters are infested with organisms that cause plant diseases.
Several virus diseases affect the vine crops, their damage is similar. Infected plants are stunted and new leaves are dwarfed, mottled or distorted. There are no chemical controls for viral diseases. Plants affected with strange mosaic-looking leaves, or multicolored, odd shaped fruit, have a virus. Pull them out of the ground and destroy them. Squashes grown here in Utah are not subject to many of the other diseases and insects that attack them in other growing areas. Summer squash must be harvested frequently and never allowed to become over mature or the plants will stop producing. Large winter squash should be mature before picking. The rind should be hard and there is no benefit to early harvest. However, the plants have to be frosted. Careful handling after harvest is important to prevent fruits from decaying.
Why aren't squash producing? Generally, it is lack of pollination. Squashes have both male and female blossoms. The female blossoms have the tiny fruit behind the blossom while the male blossoms have no such fruit. If squashes are not getting pollinated, you may have to substitute for the bees. Take the fresh, newly opened male blossom, peel the petals back and brush it around inside several female blossoms to pollinate the fruit. Because squash are so easily pollinated, saving seed is not recommended. The offspring from cross pollination are usually inferior and lack characteristics of the parent plant. Unless you go to the trouble of hand pollinating the blossoms and covering them to prevent additional pollen from contaminating your cross, buy new seeds each year.
Squashes are a very important food source in many areas of the world and should be in more gardeners' diets. They are a great choice for a gardener who doesn't like to go to all the trouble of canning or otherwise preserving the fruits of their labor.
Incidentally, it's not too early to think about getting some of your garden produce together for the state fair. Horticultural entries will be received from 8 a.m. to 2 p.m on Sept. 6. There is a 75 cent entry fee, but it would be a great time to show off those vegetables that you have worked so hard to produce this year. Additional information can be obtained by calling the Utah State Fair Information Office at 538-8445.