Squash growing success will come with a few simple growing strategies:
• Plant several squash plants. This will ensure at least one is successful and survives pests and diseases. Stagger planting times or plant seed and transplants at the same time for continuous harvest.
• Give squash the space recommended. Check spacing requirements for each variety you grow. If the garden is tight, contain the plant by pinching out the growing tips after a vine has set a few fruits. Don’t grow squash too close together; this will help deter pests and diseases.
• Pick squash at the right time. Pick summer squashes when they are young and tender. Let winter squashes and pumpkins mature until their rinds are dull and hard. Pick and toss any fruit that is discolored or rotting before other plants or fruits are affected.
Time to plant. Sow squash or set out transplants about 2 weeks after the last expected frost in spring. Sow or plant successive crops 4 weeks later.
How to plant. Sow seed or set transplants in raised mounds at least 1 foot across. Place a generous amount of aged compost into each planting hill before planting.
Outwit pests. Cucumber beetles, squash bugs, and squash vine borers must be controlled to successfully grow squash. Place floating row covers over young squash plants until they start to bloom. This will exclude attacking insects until plants are strong enough to withstand pest damage.
Train plants up stakes or trellises. Training summer squash up stakes or trellises will increase air circulation and keep plants off the ground and clean and away from pests and diseases.
Keep ahead of squash problems, pests and diseases. Here is a troubleshooting list of possible squash problems with brief control suggestions. For a full description of pests and diseases and prevention and controls click over to the Pest Problem Solver of the Disease Problem Solver. For squash growing details click to How to Grow Summer Squash and How to Grow Winter Squash.
Here are squash problems described and suggested controls and prevention:
Plants are eaten or cut off near soil level. Cutworms are gray grubs ½- to ¾-inch long that can be found curled under the soil. They chew stems, roots, and leaves. Place a 3-inch paper collar around the stem of the plant. Keep the garden free of weeds; sprinkle wood ash around base of plants.
Leaves curl under and become deformed and yellowish. Aphids are tiny, oval, and yellowish to greenish pear-shaped insects that colonize on the undersides of leaves. They leave behind sticky excrement called honeydew which can turn into a black sooty mold. Use insecticidal soap.
Leaves turn pale green, yellow, or brown; dusty silver webs on undersides of leaves and between vines. Spider mites suck plant juices causing stippling. Spray with water or use insecticidal soap or rotenone. Ladybugs and lacewings eat mites.
Leaves yellow; tiny white winged insects around plants. Whiteflies will congregate on the undersides of leaves and fly up when disturbed. Remove infested leaves and the whole plant if infestation is serious. Introduce beneficial insects into the garden.
Holes chewed in leaves, leaves skeletonized; runners and young fruit scarred. Spotted cucumber beetle is greenish, yellowish, ¼ inch (7mm) long with black spots and black head. Striped cucumber beetle has wide black stripes on wing covers. Hand pick; mulch around plants; plant resistant varieties; dust with wood ashes. Cultivate before planting to disrupt insect life cycle.
Holes in leaves and flowers; tunnels in vines and fruits. Pickle worms are the larvae of night-flying moths. Moths lay eggs on squash plants. Caterpillars feed on leaves and inside vines and fruits. Pupae may be found inside rolled leaves. Exclude moths with floating row covers. Plant fast-maturing varieties to promote strong growth before pickleworms attack. Plant a few squash as trap crops. Keep garden clean.
Leaves have yellow specks that turn brown, then black and crisp; vines wilt from point of attack. Squash bug is a flat, shield-shaped black or brownish bug with a triangle on its back; it sucks juices from plants. Trap adults beneath boards in spring, hand pick and destroy. Look under leaves for bugs.
Runners wilt suddenly; holes in stems near base of plant. Squash vine borer is a fat, white caterpillar with a brown head that emerges in late spring. It bores into stems to feed causing plants to wilt. Look for entrance holes where frass may accumulate; slit vine with knife and remove borer; bury runner at that point to re-root. Exclude adult moth with floating row covers. Time planting to avoid insect growth cycle. Plant resistant varieties.
Round to angular spots on leaves, reddish brown to black. Anthracnose is a fungus disease that spreads in high humidity and rainfall. Leaves may wither and fall. Plant may die back. Generally found in eastern North America. Spray or dust with a fixed copper- or sulfur-based fungicide every 7 to 10 days. Remove and discard infected plants. Avoid working in the garden when it is wet which can result in spread of spores. Keep tools clean.
Water-soaked blotches on leaves–not enlarging past leaf veins; water-soaked spot can appear on fruits Angular leaf spot or bacterial spot is a waterborne bacterium which causes irregular geometric patterns on leaves. Spots may turn yellow and crisp. Avoid wetting foliage with irrigation. Prune off infected leaves and stems. Clean up garden. Plant disease-resistant varieties. Rotate crops up to 2 years.
Round white powdery spots and coating on leaves. Powdery mildew is caused by fungal spores. Spores germinate on dry leaf surfaces when the humidity is high; spores do not germinate on wet leaves. Common in late summer or fall but does not result in loss of plant. Avoid water stress. Pick off infected leaves.
Irregular yellowish to brownish spots on upper leaf surfaces; grayish powder or mold on undersides. Downy mildew is caused by a fungus. Improve air circulation. Plant resistant varieties. Rotate crops. Keep garden free of plant debris.
Mottled, distorted leaves. Mosaic virus causes leaves to become thickened, brittle, easily broken from plant; plants are stunted and yields are poor. The virus is spread from plant to plant by aphids and cucumber beetles. Remove diseased plants. Remove broadleaf weeds that serve as virus reservoir.
Vines wilt suddenly and die starting with one or two leaves. Bacterial wilt clogs the circulatory system of plants. It is caused by bacteria that live in cucumber beetles and is seen often where the soil stays moist. Remove and destroy infected plants before the disease spreads. Control cucumber beetles with rotenone or sabadilla. Wash hands and clean tools with a bleach solution.
Plants are stunted and yellow; runners gradually die. Fusarium wilt is a fungal disease which infects plant vascular tissues. Fungal spores live in the soil and can be carried by cucumber beetles. Plant disease-resistant varieties. Rotate crops. Remove and destroy infected plants. Fungicides are not effective.
Water-soaked or pale green spot on leaves that turn white; fruit cracks. Scab is caused by soilborne bacterium. Disease can be cosmetic. Plant resistant varieties. If scab occurs, change varieties next year. Sulfur may be worked into soil to make it slightly acid and reduce disease.
Stems on older plants appear water soaked and turn into cracked brown cankers; fruits become water soaked. Gummy stem blight and black rot are fungus diseases. Infections can girdle stems can cause collapse. Remove and destroy infected vines. Rotate crops where fungus can persist. Grow powdery mildew resistant plants.
Some seeds fail to germinate and come up. Some squash seed are “hard” and resistant to water uptake necessary for sprouting. Soak seed in tepid water for 24 hours before planting; this will increase germination and decrease sprouting time slightly. Dry seed before planting.
Early flowers don’t set fruit. A couple of possible reasons: (1) the first flowers to appear are male; female flower appear next. Fruit is produced by female flowers. Wait until female flowers appear and are pollinated. (2) There may not be enough pollinators, mostly bees, to carry the pollen from male to female flowers. Pick off male flowers and dust the pollen into the female flowers.
Few fruits form even though plants are flowering. Not enough bees. The more bees the more flowers that are likely to set fruit. The average size of a squash is increased when the vine is pollinated by many bees.
Small fruits form then dry up. Female flowers may have blossomed before the male flowers so the female flowers went unpollinated. When female and male flowers blossom at the same time pollination will occur and fruit will grow.
Dense white mold on blossoms or small fruits. Choanephora fruit rot is a fungus that grows on blossoms and developing fruit. Remove and destroy infected blossoms and fruits. Keep the garden clean of debris that can harbor fungus. Rotate crops.
Too many fruits on the plant. Keep fruit picked from summer squash. When fruits are picked, new fruits will form. Winter squash is picked when the shell hardens.
My squash plants are putting on lots of blooms but they are falling off the stem at the base of the bloom. What is the problem and solution to this problem. The plants look healthy and growing.
Thanks for your help.
I am having a bit of problem, my squash is forming just fine but, where the bloom is at the end stays on and the squash begins to rot and mold. I decided to go and get Dawn dish washing liquid and dilute it and spray all over the squash plants. I then rinced the soap off and am hoping this will remedy the few I have got left. I dont want to put poisons on any of my plants. However I also have sugar ants all over them so when I sprayed the Dawn all the ants were gone. Do you have any suggestions?
Blossom drop happens when plants are stressed. Stress can be caused by temperature, soil moisture, nutrient imbalance, and disease. A plant will drop its blossoms to save itself and avoid the work of setting fruit–fruiting requires the right temperatures, the right soil moisture, and the right nutrients. Temperatures below 55F at night can cause squash and other warm-season plants to drop blossoms. Radical changes in temperature from warm to cool can cause blossom drop. Low soil moisture at the same time there is hot or cool weather can cause blossom drop–and so can hot, dry winds. Too much nitrogen, especially early in the season may cause blossom drop. Too little phosphorus and potassium can cause blossom drop. Diseases such as verticillium and fusarium wilts can cause blossom drop.
Generally, blossom drop will become less of a problem as the season progresses and temperatures even out. Keep your plants evenly moist–not to little and not too much water. Side dress plants with aged compost–a good even delivery of major nutrients. Simple things will cure blossom drop.
One more thing, flowers that are not pollinated will also drop. If you have few bees or insects at work in the garden and pollination is not taking place, blossoms will drop. To cure this problems, introduce male flowers to female flowers and give them a shake.
I’ve got a zucchini plant that grew quite healthy with large leaves. A few blossoms produced small fruit, then the fruit turned yellow and is dying. In addition, the leaves are now looking wilted, have slivery blotches and are drying out on the edges, dying and turning under at the edges… What’s going on? I’ve not found anything that describes this condition…
Squash fruit rot can be caused by fungal organisms; they start on blossoms and then grow into the fruits as the fruits develop. Your plants may have what is called wet rot which develops during wet weather. There is no cure for this fungal problem. You should remove and destroy the infected blossoms and fruits. Going forward be sure to remove all plant debris from the garden on a regular basis–this is where fungal organisms overwinter. Good drainage is important to avoid rots; add plenty of aged compost to the garden on a regular basis. Look for disease resistant varieties when ever possible and avoid planting crops form the same plant family in the same spot from year to year. Compost tea can be watered onto leaves to help slow fungal organisms; your use of the dish washing soap may have done the same.
I have four yellow squash plants in large containers (2 plants per 30″ x 48″ x 24″ deep) They are companion planted with
radish that have bolted and bloomed (several weeks ago).
They were doing fine except for the lack of bees. I hand pollinated and they did well, but in the last week, or so, the male blooms have disapeared and they are setting 2 to 3 inch long beautiful females that bloom and shrivel and end rot because of no pollination. All four plants are loaded with at least 20 female blooms.
We had had nearly zero rain and the plants had been watered since germination with city water. Now it has started raining often.
Something else I have been doing is polinating by snipping or pinching the male bloom off the plant, pealing the petals and using the blossom itself to pollinate the female bloom.
I am in North Florida, so the plants are several months old.
I have also picked up lots of the small german roaches.
I AM HAVING A PROBLEM WITH THE FLOWERS FALLING OFF BEFORE THEY BECOME SQUASH. HOW DO YOU TELL THE DIFFERENC BETWEEN MALE AND FEMALE FLOWERS? I LIVE IN LOUISIANA AND DAYS ARE 100 DEGREES AND NIGHTS 75 DEGREES WILL THAT MAKE A DIFFERENCE?
Mr. Albert
For many years I grew a squash from Park Seed Co. — KUTA Squash — that was by far the best tasting squash I ever had. Park discontinued the seeds a few years ago and I cannot find them anywhere.
That squash can be eaten raw with a dip, baked, boiled, grilled, fried, etc. — it has a slightly almond taste rather than the “green” taste of zucchini.
Have you had Kuta squash? Do you have any suggestions where the seeds can be purchased?
Thanks,
Dick Gordon
Blossoms are falling off my straight neck squash plants – no sign of aphids, rot, or bugs in general – looks like they were cut off…good size blossoms that appeared pollinated. What could be doing that?
Thanks for this very good description of hand pollination. You can also use a cotton swab to transfer pollen from the male flowers to the female flowers.
Female flowers will have a little bump at the stem end of the blossom. Male flowers appear first, followed by female flower. Both male and female flowers much be present for insects to transfer pollen from the male to the female. You can save the pollen from males and shake them over the female flowers appearing a few days later. One male blossom will pollinate several female flowers. Yes, temperature can cause blossoms to drop. Shade your plants when the temperatures are over 95F.
Blossom drop is usually an environmental disorder. It can commonly occur during hot, dry conditions when the soil moisture is low; plants become stressed and the blossoms are sacrificed to keep the plant alive. Sometime blossom drop can occur when the weather goes from hot to cool and wet. Keep fruiting vegetables well watered in hot, dry weather; that is keep the soil moist 3 to 4 inches below the soil surface–use your finger to judge the soil moisture content. You can also spray your plants with seaweed extract–this often helps, making plants less susceptible to disease. Shade cloth over a frame or over hoops can shade blossoms and keep plants cooler. Too much fertilizer–especially nitrogen–can add to plant stress in hot weather.
Zucchini with silvery blotched and leaves drying and turning under: suspect a melon aphid or sucking insect at work. Spray the top and undersides of leaves with a strong stream of water to dislodge aphids. A reflective mulch will confuse and repel flying insects. A garlic spray will deter many sucking or rasping insects (rasping insects strip away the green chlorophyll of a leaf leaving it silvery and see-through). Keep plants evenly moist to avoid stress; stressed plants are most susceptible to insects and disease. Avoid using fertilizers high in nitrogen; this too can stress vegetables, especially in warm and hot weather.
Kuta squash–which many consider a gourmet squash–does not seem to be offered by any seed companies currently. Kuta (Cucurbita pepo) is a F-1 hybrid; it is unlikely any seed savers will have this seed. Kuta takes 48 days to harvest; when young it has a light green fruit. It has a crisp and smooth, sweet and nutty flavor. Young it can be eaten raw in salads or dips. As Kuta matures it can be prepared like eggplant. Fully mature, Kuta turns dark green and can be baked or stuffed like a winter squash. It has good keeping qualities. Park Seeds in Greenwood, South Carolina (find them online) was the last seed company to offer Kuta. That would be a good place to send your first inquiry. In the past, Kuta was offered by Lagomarsino Seeds in Sacramento (last address 5675-A Power Inn Rd. Sacramento, 95824), California and by Porter & Sons, Seedsmen in Stephenville, Texas (last address PO Box 104, Stephenville TX, 76401).