Q: I have a question about my zucchini. The zucchini get 2 to 4 inches long and then they get soft and break off. Am I lacking something that makes this happen?
— Marian Harrigle, Catasauqua
A: Zucchini plants are known for their prolific crops so it is unusual when they fail to produce. While Marian’s problem is specific, an overview of the plant’s needs and problems may help others who are experiencing difficulties with their zucchini plants.
Zucchini plants need:
Light: Full sun or at least six hours of direct sunlight.
Soil: Moist but well-drained soil with no standing water or constantly muddy areas. They thrive in slightly acid soil (pH 6.0-6.5).
Spacing: 2 to 3 feet between plants, as recommended for your particular variety, to assure proper air circulation.
Temperature: Avoid setting out too soon, frosts and cool temperatures can kill or permanently stunt plants.
Pollination: The plants produce both male and female flowers— you need both blooming at the same time. Pollinators such as bees and other insects are necessary. Uncooperative weather— hot temperatures, high humidity, cool weather — can decrease the viability of the pollen or decrease the chances of pollination.
Germination: Use fresh seed and consider briefly soaking the seeds in mild warm water to start softening the seed coating. Dry the seed before planting.
Failure to fruit: This can be the result of weather, timing, lack of pollinators and improper fertilization. Too hot or cool weather affects not only the presence of pollinators but also the condition of the pollen. If the timing of the male blooms is not coordinated with the later-emerging female blossoms, there is no pollen when needed. If you over-fertilize with a high nitrogen fertilizer, you will get plenty of leaves and no flowers. No flowers means no zucchini.
Squash blossom end rot: Look for soft and rotting fruit, often with a black area on the blossom end of the squash. This is usually caused by a problem with water uptake, something affected by the availability of calcium in the soil. But before you dump a calcium supplement in the garden, do a bit more research. You may have plenty of calcium in the soil but the pH of the soil makes it unavailable to the plants. A soil test will let you know if the calcium is present but unavailable or if there is actually a deficiency of calcium in the soil. Then, adjust the pH or add calcium to correct the problem. Temperatures above 90 degees also can affect nutrient uptake. Keep plants evenly watered because water uptake helps transport soil nutrients to the plant. There is some rather limited data that a foliar calcium supplement may help but it is definitely a stopgap measure. This would seem to be the most probable problem for Marian.
Then there are the problems with insects and disease:
Aphids: Look for yellow and distorted shaped leaves, stunted growth, and a black substance, honeydew or aphid excrement, on or under the plant. Use a strong spray of water on the tops and undersides of the plants to dislodge the aphids.
Cucumber beetles: Striped beetles that attack the stems and leaves of older plants. They also transmit wilt and mosaic viruses. The larvae live in the soil and eat the plant roots. Clean up after harvest and remove or mow nearby dense grass. Handpick adults off your plants. Encourage beneficial insects such as ladybugs and lacewings. Cover seedlings and plants with row covers then remove when flowering or hand pollinate then re-cover.
Cutworms: Look for plants that are eaten or cut off at the soil line. Set out plants with paper collars about three-inches tall around the stems. Keep weeds and debris clear under and near plants.
Spider mites: Look for pale green, yellow or brown leaves with dusty silver webs on the underside of the plants. These mites can be dislodged with a strong stream of water or by using an insecticidal soap. Also note, beneficial insects that will eat the mites.
Squash bugs: These sap suckers cause the plants to collapse and die. The leaves are spotted and then turn brown. Row covers will keep out adults and limit egg laying.
Vine borers: These insects lay eggs in the soil and the young emerge and bore into the base of the plant stem. They kill the plants by destroying the vascular system of the plant. Look for small holes in the stem and small piles of frass (bug poop) near the holes. You can slit the stem and remove the insect. Close the hole and bury the stem.
General options to control pests: While there are pesticides available, make sure any you decide to use are appropriate for food crops and your specific insect. Encourage beneficial insects by providing food for all stages of life and by avoiding harmful pesticides. Keep the areas free of weeds and debris and clear up after harvest to eliminate wintering over spots and hiding places. Identify your particular insect and select the appropriate resolution.
Diseases are almost always fatal:The first and best solution is to remove and destroy any affected plants. Keep insects under control as they often infect plants as they feed. Rotate crops to avoid soil borne bacteria and insect larvae carrying over from season to season
Bacterial wilt: Wilted plants and misshapen leaves.
Powdery mildew: White powder in spots or covering leaves usually the result of too much shade or uneven watering. Pick off and destroy affected leaves and avoid water stress. Powdery mildew, unless extremely rampant, is generally a cosmetic problem.
Downy mildew: It appears first on the undersides of the leaves then produces yellow spotting on the top surface. Downy mildew thrives in high humidity and cool days or nights. It will damage or stunt your plants.
Squash mosaic virus: This virus is fatal. Symptoms include reduced growth and poor branching, mottling on the fruit and distorted leaves. Remove and destroy affected plants.
Sue Kittek is a freelance garden columnist, writer, and lecturer. Send questions to Garden Keeper at grdnkpr@gmail.com or mail: Garden Keeper, The Morning Call, PO Box 1260, Allentown, PA 18105.
Week in the Garden
Planting:
Start a final sowing of beets, bush green beans, chard, cucumbers, melons, okra, potatoes, pumpkins, summer squash, and sweet corn.
Plant but protect from heat: late-season cabbage, carrots, cauliflower, peas, and broccoli for late summer or early fall harvest.
Replace spent containers of pansies with heat-loving annuals. Move the pansies to cool shade and keep them watered during the summer if you want to keep them for the fall.
Hold new plants until the weather cools.
Seasonal:
Stalk tall flowers and provide supports for vining plants.
Shear back damaged or ratty looking foliage on columbine (Aquilegia sp.) and cranesbill geraniums. Cut common bleeding heart (Dicentra spectablis) back to its base foliage.
Prune back clematis (Group I, C. Montana rubens, for example) and deutzia after blooming.
Give a light feeding to hellebores such as the Lenten rose. Stop pinching back helenium, chrysanthemums and asters now.
Deadhead flowers and trim damaged, diseased, and dead foliage to keep beds tidy.
Cut back peony flower stems as the blooms fade. Allow the greens to grow until fall and then cut back.
Clip back iris flower stems as the blooms fade; divide crowded beds.
Lawn:
Treat for chinch bugs and sod webworms.
Cut lawn as needed
Keep newly seeded or sodded lawns watered; supplement rain in weeks where less than an inch
Apply preemergent crabgrass control in the next few weeks.
Fill in holes and low spots in lawn.
Apply corn gluten-based weed control in the garden; reapply at four to six week intervals.
Chores:
Harvest crops regularly, at least every other day.
Check hoses; replace washers and correct leaky connections
Dump standing water and remove anything that may collect rainwater to help control mosquito populations .
Check seed inventory for second or later plantings or for late crops and fall planting.
Inventory and restock seed starting and potting supplies. Clean, disinfect and store pots and trays.
Provide deer, rabbit and groundhog protection for vulnerable plants. Reapply taste or scent deterrents.
Clean and fill bird feeders and birdbaths regularly. Clean up spilled seed and empty hulls. Once a week scrub/brush birdbaths before refilling to dislodge any mosquito eggs.
Tools, equipment, and supplies:
Start planning for fall. Order bulb and plants for early fall shipment.
Check seed inventory for late crops and fall planting.
Sharpen tool blades, get fresh gas, check and/or replace oil. Send mowers and tractors for tune-up or repair.
Clean and oil hand tools.Check and store winter/fall equipment, repair or replace as needed.
Safety:
Clear lawns of debris and keep pets and children away from areas being mowed.
Don’t prune anything that can’t be reached from the ground. Hire a certified and insured tree pruner for high pruning or heavy branches or for any work around power lines.
Store garden chemicals indoors away from pets and children. Discard outdated ones at local chemical collection events.
Photograph storm damage before clearing or repairing for insurance claims and file promptly.
Avoid tick and mosquito bites: Use an insect repellent containing Deet on the skin. Apply a permethrin product to clothing.
Wear light-colored clothing, long sleeves, hats and long pants when working in the garden.
Stay hydrated. Drink water or other non-caffeinated, nonalcoholic beverages.
Apply sunscreen, wear hats and limit exposure to sun. Wear closed-toe shoes and gloves; use eye protection; and use ear protection for loud power tools.
