Originally Published In The Deseret News -- Wednesday, August 12, 1992
Don't Worry About Afternoon Wilting, But Morning Wilting Signals The Plants Have A Problem.
Squash is a very important home garden vegetable. An important food source for Native Americans long before Columbus came, there are many different kinds of squash, but they are generally classified as two kinds. Summer squash is eaten as small, immature fruits, while winter squash is allowed to ripen with a hard shell so it can be stored for future use.
Squash is a warm-season plant and loves hot weather and plenty of water. Add 11/2 inches of moisture per week throughout the summer in the form of deep, infrequent irrigation. Temporary wilting in the heat of the afternoon is common because of the large leaves. Wilted plants in the morning are sending out distress signals that something is wrong. The most common cause is the lack of water.
Squash dieback is an all too common problem. There are many reasons why squash is not productive and healthy. Common insect pests include flea beetles, aphids, mites and squash bugs. These pests feed on the underside of the leaf, so controls need to be directed there. Sprayers must be modified to spray the underside of the leaf. Insecticidal soaps control many aphids and mites. Squash bugs are a more difficult pest. Hand picking the bugs in the early morning or putting boards for them to hide under and then squashing the squash bugs is an unpleasant but effective control. Sabadilla dust or Thiodan also give some control.
The damage caused by squash bugs is a common and often-discussed problem. Many pathologists feel that squash bugs do little if any damage. Their presence indicates plants that are stressed by various fungal diseases, the most serious of which is fusarium wilt.
Wilt diseases, as the name implies, cause a sudden wilting symptom. To autopsy the plant, cut through the stem after you remove it from the ground. A normal stem is white and clean on the inside, while plants infected with wilt diseases have streaked, discolored and mushy stems. Controls for root diseases are very limited. Rotation is practiced but is not totally effective. Allowing plants to stand in water increases problems with fungal diseases. Grow squash on well-drained soils. Some varieties are extremely susceptible to wilt; these include Prolific, Straightneck and Crookneck summer squash as well as Hubbard and Banana winter squash.
Powdery mildew is another common fungal disease. Powdery mildew that shows up late in the season needs no controls. Young, productive plants can be sprayed earlier with a fungicide to keep mildew under control if the disease is severe.
One common complaint of home gardeners is plants that flower but produce no fruits. All vine crops produce male flowers first. Patience will take care of that problem, as female flowers will start within a few weeks. When there are abundant female flowers, there are two reasons for no fruit set. Fruit already growing on the plant inhibits fruit set until they are mature or harvested. Squash depend on insects, mainly honey bees for pollination. If there are no honey bees in the area, fruits may not set due to lack of pollination. Insufficient pollination results in deformed fruits.
You can easily pollinate the female flowers by taking a freshly opened male flower, turning it inside out and running it around inside a freshly opened female flower. Do this in the early morning right after the blossoms open. You can also use a soft artist brush to move the pollen from the male flower onto the female flower.
Harvest summer squash while they are still small, soft and succulent. Large, overmature summer squash are of no value except for compost. Frequent harvest ensures continued production of these tender, young vegetables. They are versatile for either fresh eating or cooking in a variety of ways.
Winter squashes and pumpkins are harvested when mature. The skin hardens until it cannot be easily penetrated by a thumbnail. Mature squashes can be stored most of the winter if protected from freezing. They are a nutritious vegetable high in vitamin A and other vitamins and minerals.
Squash, like other plants, has its share of problems. Fortunately most of these are manageable and not life-threatening. Wilt diseases are the most common and serious squash problems. Rotation, good watering practices, and resistant varieties help control this problem. Inadequate pollination can be overcome if you are willing to do the same work that the bees do. Attention to these details will reward you with an abundant harvest of these nutritious vegetables.
© 1998 Deseret News Publishing Co.